SyncValsverifier → artifact → classifier → verdict
SyncVals · Trajectory

worst-group-spurious-dfr

claude-code claude-opus-4-8 ✗ failed GOOD_FAILURE ↑ View task
Solved from the instruction alone, tests/ and solution/ were withheld from the agent's workspace and restored only for grading.
Reward = tests/test.sh exit code (0 → resolved); the classification below is post-hoc and cannot change it.
Classification , post-hoc; cannot change the reward
GOOD_FAILUREHonest miss, the agent ran correctly but couldn't solve it. Expected for a hard task; the task is sound.
SubtypeInsufficient Training Optimization - Model Accuracy Below Threshold
EvidenceTest output shows: 'COMPONENT CONFORMANCE SUITE: 194/194 cases passed (all milestones pass: True)' but 'FINAL METRIC: worst-group accuracy = 0.8067 < threshold 0.86'. Agent successfully implemented the entire numpy-only deep learning framework with correct backward passes for 60+ operations, conv2d/pool/batchnorm/groupnorm, and all robustness losses. However, the trained model achieved 0.8067 worst-group accuracy vs the required 0.86 threshold (93.8% of the way there).
Root causeThe agent correctly implemented the complete framework and all component checks passed, but the training recipe (using the group-weighted loss and group-balanced dataset retraining) did not push the model's worst-group accuracy high enough to clear the sealed threshold of 0.86. This is a training optimization limitation, not a framework or instruction issue.
RecommendationN/A - task is fine. This is a hard research benchmark task (explicitly difficulty: hard) where the agent must implement a complete from-scratch deep-learning framework AND train a model with strong spurious correlations to achieve a high worst-group accuracy threshold. A ~0.81 worst-group accuracy represents correct implementation but insufficient training tuning. The task instruction is clear and complete, and the grading uses an external sealed test set which is appropriate for this research task.
Trajectory
Tool-by-tool agent trajectory
233 tool calls · 3 tool types · 260 steps
Agent session started, model: claude-opus-4-8 · 29 tools available · cwd: /app
I'll start by exploring the structure of the task files.

List app structure

shell
ls -la && echo "---SUBMISSION---" && ls -la submission/ && echo "---DATA---" && ls -la data/
output
total 89
drwxr-xr-x  4 user user  4096 Jun 30 22:55 .
drwxr-xr-x 21 root root  4096 Jun 30 22:55 ..
-rw-r--r--  1 user user 14914 Jun 30 22:55 PROMPT.txt
-rw-r--r--  1 user user     5 Jun 30 22:55 agent.pid
-rw-r--r--  1 user user     0 Jun 30 22:55 agent.stderr
-rw-r--r--  1 user user  4498 Jun 30 22:56 agent_trajectory.jsonl
drwxr-xr-x  2 user user    60 Jun 30 22:55 data
-rw-r--r--  1 user user     0 Jun 30 22:55 run.log
-rwxr-xr-x  1 user user 45855 Jun 30 11:01 run_checks.py
drwxr-xr-x  3 user user   128 Jun 30 22:55 submission
-rwxr-xr-x  1 user user  1318 Jun 30 11:01 test.sh
-rwxr-xr-x  1 user user   629 Jun 30 11:01 timer.sh
---SUBMISSION---
total 100
drwxr-xr-x 3 user user   128 Jun 30 22:55 .
drwxr-xr-x 4 user user  4096 Jun 30 22:55 ..
drwxr-xr-x 2 user user  4096 Jun 30 22:55 __pycache__
-rw-r--r-- 1 user user 48121 Jun 30 11:01 autograd.py
-rw-r--r-- 1 user user  1692 Jun 30 11:01 data.py
-rw-r--r-- 1 user user 23705 Jun 30 11:01 nn.py
-rw-r--r-- 1 user user 12275 Jun 30 11:01 optim.py
-rw-r--r-- 1 user user  2900 Jun 30 11:01 train.py
---DATA---
total 11108
drwxr-xr-x 2 user user      60 Jun 30 22:55 .
drwxr-xr-x 4 user user    4096 Jun 30 22:55 ..
-rw-r--r-- 1 user user 3953364 Jun 30 11:01 reweight.npz
-rw-r--r-- 1 user user 7411924 Jun 30 11:01 train.npz

Count lines in files

shell
wc -l submission/*.py run_checks.py test.sh 2>/dev/null
output
1306 submission/autograd.py
    44 submission/data.py
   543 submission/nn.py
   272 submission/optim.py
    65 submission/train.py
   937 run_checks.py
    24 test.sh
  3191 total
Let me read all the files to understand the structure.

/app/submission/autograd.py

contents
1	"""Reverse-mode automatic differentiation over numpy arrays.
2	
3	YOU MUST IMPLEMENT EVERYTHING MARKED ``# TODO`` / ``raise NotImplementedError`` using numpy
4	ONLY. No torch/jax/tensorflow/autograd/etc. The grader's conformance suite differentiates each
5	op below with central finite differences and compares against YOUR analytic backward, so every
6	backward must be correct (a single wrong reduction / Jacobian / group-weighting fails the checks).
7	
8	A ``Tensor`` wraps one ``numpy.ndarray`` (stored as ``float64`` in ``self.data``) and records
9	the op that produced it so ``.backward()`` can accumulate ``.grad`` into every leaf.
10	
11	CONTRACT (the grader builds its own reference against this exact API):
12	* ``Tensor(data, requires_grad=False)`` -- ``self.data`` is ``float64``; ``self.grad`` is None
13	  until backward, then a same-shape ``float64`` array. requires_grad leaves accumulate grad.
14	* Every op returns a NEW Tensor whose ``requires_grad`` is the OR of its differentiable inputs,
15	  and whose ``_backward`` closure does ``input._accum(local_grad)`` (so multiple paths add up).
16	* ``t.backward(grad=None)`` -- seeds ``grad`` (all-ones for a scalar) and walks the graph in
17	  reverse topological order, calling each node's ``_backward``. Repeated backward accumulates.
18	* BROADCASTING: binary ops broadcast like numpy; the backward MUST reduce (sum) the upstream
19	  gradient back to each input's ORIGINAL shape (use the provided ``_unbroadcast`` helper).
20	* 
…[truncated 52049 chars]
Now let me read the other files.

/app/submission/nn.py

contents
1	"""Neural-network layers + models + the robustness machinery, built on YOUR autograd engine.
2	
3	Implement every ``# TODO`` forward (and the robustness-helper bodies). The parameters +
4	``named_params`` naming + the checkpoint round-trip are already wired; you compose the autograd
5	ops. The grader checks each layer's forward against its OWN reference AND finite-difference-checks
6	the gradients that flow through your autograd, so the composition must be exactly right.
7	
8	THE FINAL-METRIC MODEL is the pinned ``SmallCNN`` (a conv FEATURE EXTRACTOR + a single linear
9	CLASSIFIER). The split is what makes last-layer retraining (DFR) on a group-balanced set
10	expressible against the pinned graph: freeze the extractor and re-fit ONLY ``classifier``.
11	``featurize(X, training)`` returns the post-ReLU embedding so you can freeze the extractor.
12	
13	The other layers/models (Linear / Conv2d / BatchNorm2d / BatchNorm1d / LayerNorm / Dropout /
14	AvgPool2d / MLP / ResidualMLP / a TinyConvNet) are exercised by the conformance suite across a
15	WIDE surface -- each is an independent potential bug. The robustness machinery (``GroupDROState``
16	exponentiated-gradient adversary-weight update, ``balanced_group_weights``,
17	``class_balanced_weights``, ``log_class_prior``) is the domain-specific heart this task adds; the
18	``robust`` milestone checks them.
19	
20	SmallCNN naming contract (do not change -- the verifier indexes by these exact keys):
21	  conv1.weight (Wd,3,3,3) | con
…[truncated 24273 chars]

/app/submission/optim.py

contents
1	"""Optimizers + LR schedulers + grad clipping over a flat list of autograd ``Tensor`` parameters.
2	
3	Implement the ``# TODO`` update math. All optimizers operate IN PLACE on ``param.data`` using
4	``param.grad``. ``zero_grad()`` resets every grad to None. ``t`` is the 1-based step count. The
5	grader runs one (and several) steps of each and compares your updated params against its
6	reference within a tight tolerance, so the math must be EXACTLY right -- every optimizer /
7	scheduler / clipper is an independent potential bug.
8	
9	The training recipe uses AdamW (decoupled weight decay) + ``clip_grad_norm`` for the ERM
10	extractor and the last-layer (DFR) retrain; the rest of the zoo is graded for parity.
11	
12	  SGD     : g = grad + wd*p; v = mu*v + g; upd = (g + mu*v) if nesterov else v; p -= lr*upd
13	  Adagrad : g = grad + wd*p; s += g^2; p -= lr*g/(sqrt(s)+eps)
14	  RMSprop : g = grad + wd*p; s = alpha*s + (1-alpha)*g^2; p -= lr*g/(sqrt(s)+eps)
15	  Adam    : g = grad + wd*p (COUPLED L2); m,v EMA; mhat=m/(1-b1^t); vhat=v/(1-b2^t);
16	            p -= lr*mhat/(sqrt(vhat)+eps)
17	  AdamW   : DECOUPLED wd; m,v EMA; p -= lr*( mhat/(sqrt(vhat)+eps) + wd*p )
18	  Adamax  : m=b1*m+(1-b1)*g; u=max(b2*u, |g|); p -= (lr/(1-b1^t))*m/(u+eps)   (infinity-norm)
19	  NAdam   : m,v EMA; mhat=m/(1-b1^t); vhat=v/(1-b2^t);
20	            mnes = b1*mhat + (1-b1)*g/(1-b1^t);  p -= lr*mnes/(sqrt(vhat)+eps)
21	  Lion    : upd = sign(b1*m + (1-b1)*g); p -= lr*(upd + wd*p); m = b2*m + (1-b2
…[truncated 11759 chars]

/app/submission/data.py

contents
1	"""Data loading + group helpers for the worst-group / spurious-correlation task.
2	
3	Implement the ``# TODO`` bodies (numpy only). The splits ship as ``.npz`` files with arrays
4	``X`` (N,3,S,S) float, ``y`` (the SHAPE class to predict) and ``g`` (the spurious background-color
5	id). A "group" is the pair ``(y, g)``; ``group_ids(y, g, n_classes) = y*n_classes + g`` flattens it
6	to a single id in ``[0, n_classes**2)``.
7	"""
8	from __future__ import annotations
9	
10	from typing import Dict, Tuple
11	
12	import numpy as np
13	
14	
15	def load_npz(path: str) -> Tuple[np.ndarray, np.ndarray, np.ndarray]:
16	    """Load (X, y, g) from a .npz; return float64 X, int64 y, int64 g. (Provided.)"""
17	    d = np.load(path)
18	    return (np.asarray(d["X"], dtype=np.float64),
19	            np.asarray(d["y"], dtype=np.int64),
20	            np.asarray(d["g"], dtype=np.int64))
21	
22	
23	def group_ids(y: np.ndarray, g: np.ndarray, n_classes: int) -> np.ndarray:
24	    """Flatten (y, g) to a single group id y*n_classes + g (int64)."""
25	    # TODO
26	    raise NotImplementedError("group_ids")
27	
28	
29	def iterate(X, y, g, batch_size, rng):
30	    """Yield (Xb, yb, gb) minibatches over a random permutation of the dataset."""
31	    # TODO
32	    raise NotImplementedError("iterate")
33	
34	
35	def worst_group_acc(preds, y, g, n_classes) -> Tuple[float, float, Dict[int, float]]:
36	    """Return (min over (y,g) groups of within-group accuracy, average accuracy, per-group dict)."""
37	
…[truncated 318 chars]

/app/submission/train.py

contents
1	"""Training entry point. Implement your worst-group-robust recipe, train the pinned SmallCNN,
2	and save the checkpoint the grader will load.
3	
4	Run it however you like (e.g. ``python3 /app/submission/train.py``). It MUST end by writing
5	``/app/submission/model.npz`` via ``save_checkpoint`` below. The grader loads that file into its
6	OWN reference SmallCNN (architecture pinned to WIDTH/EMBED_DIM below -- keep these) and evaluates
7	WORST-GROUP accuracy on a SEALED, group-balanced test set; you pass the metric part iff
8	worst-group accuracy >= the frozen threshold. (You ALSO must pass the component conformance suite
9	over autograd.py / nn.py / optim.py.)
10	
11	A naive cross-entropy ("ERM") run on the correlated train split will reach high AVERAGE accuracy
12	but ~0 worst-group accuracy -- it keys on the spurious background color. Removing that reliance is
13	the task. One well-known cheap recipe: train the feature extractor on the correlated data, then
14	RE-FIT ONLY the final ``classifier`` on the GROUP-BALANCED reweight split with a group-balanced
15	(group-weighted) loss so the head stops keying off color. You are free to use any method, as long
16	as you submit a state_dict for the pinned architecture.
17	"""
18	from __future__ import annotations
19	
20	import argparse
21	import json
22	import os
23	import sys
24	
25	import numpy as np
26	
27	sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
28	sys.path.insert(0, "/app")
29	sys.path.insert(0, "/app/su
…[truncated 1589 chars]
Now let me look at the check runner and the data shapes.

/app/run_checks.py

contents
1	#!/usr/bin/env python3
2	"""PUBLIC component check runner for the from-scratch numpy framework (worst-group / spurious-
3	correlation task).
4	
5	Run this AS OFTEN AS YOU LIKE while you implement to get a per-check progress signal:
6	
7	    python3 /app/run_checks.py                      # check the framework in /app/submission
8	    python3 /app/run_checks.py --submission /dir
9	    python3 /app/run_checks.py --only robust        # focus a single milestone
10	
11	It imports YOUR modules from /app/submission (autograd.py / nn.py / optim.py / data.py), exactly
12	as the grader does, and runs a PUBLIC portion of the component conformance suite, printing a clear
13	per-check report. Each FAIL line names the exact op / layer / optimizer / robustness-loss that is
14	wrong.
15	
16	HOW THIS RELATES TO YOUR GRADE
17	------------------------------
18	This runner is a DEBUGGING AID, not the grader. It checks your framework against self-consistent
19	references it computes on its own:
20	  * autograd_grads : central FINITE-DIFFERENCE of YOUR forward vs YOUR analytic backward.
21	  * nn_forward     : mathematical PROPERTIES your forward must satisfy.
22	  * optim          : YOUR optimizer step vs the closed-form update re-derived here in numpy, for
23	                     every optimizer + the LR schedulers + both grad clippers.
24	  * robust         : finite-diff of YOUR robustness-loss backward + the per-group-normalization /
25	                     Group-DRO / weight-helper PROPERTI
…[truncated 47999 chars]
Let me check the data shapes.

Inspect data

shell
python3 -c "
import numpy as np
d=np.load('data/train.npz'); print('train', {k:(d[k].shape,d[k].dtype) for k in d})
print('y vals', np.unique(d['y']), 'g vals', np.unique(d['g']))
import collections
print('group counts', collections.Counter(zip(d['y'].tolist(), d['g'].tolist())))
r=np.load('data/reweight.npz'); print('reweight', {k:(r[k].shape,r[k].dtype) for k in r})
print('rw group counts', collections.Counter(zip(r['y'].tolist(), r['g'].tolist())))
"
output
train {'X': ((2400, 3, 16, 16), dtype('float32')), 'y': ((2400,), dtype('int64')), 'g': ((2400,), dtype('int64'))}
y vals [0 1 2 3] g vals [0 1 2 3]
group counts Counter({(2, 2): 586, (0, 0): 585, (1, 1): 580, (3, 3): 576, (1, 3): 11, (3, 0): 10, (3, 2): 7, (0, 2): 7, (3, 1): 7, (0, 3): 7, (2, 3): 6, (1, 0): 6, (2, 1): 5, (2, 0): 3, (1, 2): 3, (0, 1): 1})
reweight {'X': ((1280, 3, 16, 16), dtype('float32')), 'y': ((1280,), dtype('int64')), 'g': ((1280,), dtype('int64'))}
rw group counts Counter({(2, 0): 80, (2, 1): 80, (3, 0): 80, (0, 1): 80, (3, 3): 80, (2, 3): 80, (3, 1): 80, (1, 0): 80, (0, 2): 80, (1, 3): 80, (1, 1): 80, (1, 2): 80, (2, 2): 80, (0, 0): 80, (3, 2): 80, (0, 3): 80})
Now I have full understanding. Let me implement. Starting with `autograd.py` `backward` and all the ops. Let me begin with the topological backward.

/app/submission/autograd.py

− removed
        TODO: implement the topological walk + seeding. (The per-op ``_backward`` closures do
        the local accumulation; here you only orchestrate the order + seed ``self.grad``.)
        """
        raise NotImplementedError("Tensor.backward")
+ added
        TODO: implement the topological walk + seeding. (The per-op ``_backward`` closures do
        the local accumulation; here you only orchestrate the order + seed ``self.grad``.)
        """
        topo: List[Tensor] = []
        visited = set()

        def build(node: "Tensor"):
            if id(node) in visited:
                return
            visited.add(id(node))
            for p in node._parents:
                build(p)
            topo.append(node)

        build(self)
        if grad is None:
            grad = np.ones_like(self.data)
        else:
            grad = _as_f64(grad)
        self._accum(grad)
        for node in reversed(topo):
            node._backward()

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)
Now the binary ops:

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("add backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None:
            return
        if a.requires_grad:
            a._accum(_unbroadcast(out.grad, a.data.shape))
        if b.requires_grad:
            b._accum(_unbroadcast(out.grad, b.data.shape))
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("sub backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None:
            return
        if a.requires_grad:
            a._accum(_unbroadcast(out.grad, a.data.shape))
        if b.requires_grad:
            b._accum(_unbroadcast(-out.grad, b.data.shape))
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("mul backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None:
            return
        if a.requires_grad:
            a._accum(_unbroadcast(out.grad * b.data, a.data.shape))
        if b.requires_grad:
            b._accum(_unbroadcast(out.grad * a.data, b.data.shape))
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("div backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None:
            return
        if a.requires_grad:
            a._accum(_unbroadcast(out.grad / b.data, a.data.shape))
        if b.requires_grad:
            b._accum(_unbroadcast(-out.grad * a.data / (b.data * b.data), b.data.shape))
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("power backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not a.requires_grad:
            return
        a._accum(out.grad * pf * (a.data ** (pf - 1.0)))
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("maximum backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None:
            return
        ad, bd = a.data, b.data
        eq = (ad == bd)
        ga = np.where(ad > bd, 1.0, 0.0) + 0.5 * eq
        gb = np.where(bd > ad, 1.0, 0.0) + 0.5 * eq
        if a.requires_grad:
            a._accum(_unbroadcast(out.grad * ga, a.data.shape))
        if b.requires_grad:
            b._accum(_unbroadcast(out.grad * gb, b.data.shape))
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("minimum backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None:
            return
        ad, bd = a.data, b.data
        eq = (ad == bd)
        ga = np.where(ad < bd, 1.0, 0.0) + 0.5 * eq
        gb = np.where(bd < ad, 1.0, 0.0) + 0.5 * eq
        if a.requires_grad:
            a._accum(_unbroadcast(out.grad * ga, a.data.shape))
        if b.requires_grad:
            b._accum(_unbroadcast(out.grad * gb, b.data.shape))
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("where backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None:
            return
        if a.requires_grad:
            a._accum(_unbroadcast(np.where(c, out.grad, 0.0), a.data.shape))
        if b.requires_grad:
            b._accum(_unbroadcast(np.where(c, 0.0, out.grad), b.data.shape))
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)
Now the unary math ops:

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("exp backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not a.requires_grad:
            return
        a._accum(out.grad * e)
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("log backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not a.requires_grad:
            return
        a._accum(out.grad / a.data)
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("sqrt backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not a.requires_grad:
            return
        a._accum(out.grad * 0.5 / s)
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("abs backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not a.requires_grad:
            return
        a._accum(out.grad * np.sign(a.data))
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("clip backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not a.requires_grad:
            return
        mask = (a.data > lo) & (a.data < hi)
        a._accum(out.grad * mask)
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)
Now reductions/reshape. First `sum`:

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("sum backward")  # TODO
    out._backward = _bw
    return out


def mean(a, axis=None, keepdims=False) -> Tensor:
+ added
    def _bw():
        if out.grad is None or not a.requires_grad:
            return
        g = out.grad
        if axis is not None and not keepdims:
            axes = (axis,) if isinstance(axis, int) else tuple(axis)
            axes = tuple(ax % a.data.ndim for ax in axes)
            g = np.expand_dims(g, axes)
        a._accum(np.broadcast_to(g, a.data.shape).copy())
    out._backward = _bw
    return out


def mean(a, axis=None, keepdims=False) -> Tensor:

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("mean backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not a.requires_grad:
            return
        g = out.grad
        if axis is not None and not keepdims:
            axes = (axis,) if isinstance(axis, int) else tuple(axis)
            axes = tuple(ax % a.data.ndim for ax in axes)
            g = np.expand_dims(g, axes)
        a._accum(np.broadcast_to(g, a.data.shape) / n)
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("max backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not a.requires_grad:
            return
        g = out.grad
        if axis is not None and not keepdims:
            axes = (axis,) if isinstance(axis, int) else tuple(axis)
            axes = tuple(ax % a.data.ndim for ax in axes)
            g = np.expand_dims(g, axes)
        mask = (a.data == m)
        cnt = mask.sum(axis=axis, keepdims=True)
        a._accum(mask * g / cnt)
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("min backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not a.requires_grad:
            return
        g = out.grad
        if axis is not None and not keepdims:
            axes = (axis,) if isinstance(axis, int) else tuple(axis)
            axes = tuple(ax % a.data.ndim for ax in axes)
            g = np.expand_dims(g, axes)
        mask = (a.data == m)
        cnt = mask.sum(axis=axis, keepdims=True)
        a._accum(mask * g / cnt)
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("transpose backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not a.requires_grad:
            return
        if axes is None:
            a._accum(np.transpose(out.grad))
        else:
            inv = np.argsort(axes)
            a._accum(np.transpose(out.grad, tuple(inv)))
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("reshape backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not a.requires_grad:
            return
        a._accum(out.grad.reshape(a.data.shape))
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("getitem backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not a.requires_grad:
            return
        gz = np.zeros_like(a.data)
        np.add.at(gz, idx, out.grad)
        a._accum(gz)
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("concat backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None:
            return
        offsets = np.cumsum([0] + sizes)
        for i, t in enumerate(ts):
            if t.requires_grad:
                sl = [slice(None)] * out.grad.ndim
                sl[axis] = slice(offsets[i], offsets[i + 1])
                t._accum(out.grad[tuple(sl)])
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("stack backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None:
            return
        for i, t in enumerate(ts):
            if t.requires_grad:
                sl = [slice(None)] * out.grad.ndim
                sl[axis] = i
                t._accum(out.grad[tuple(sl)])
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("matmul backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None:
            return
        go = out.grad
        if a.requires_grad:
            da = go @ np.swapaxes(b.data, -1, -2)
            a._accum(_unbroadcast(da, a.data.shape))
        if b.requires_grad:
            db = np.swapaxes(a.data, -1, -2) @ go
            b._accum(_unbroadcast(db, b.data.shape))
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)
Now nonlinearities:

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("relu backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not a.requires_grad:
            return
        a._accum(out.grad * (a.data > 0.0))
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("leaky_relu backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not a.requires_grad:
            return
        a._accum(out.grad * np.where(a.data > 0.0, 1.0, sl))
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("sigmoid backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not a.requires_grad:
            return
        a._accum(out.grad * s * (1.0 - s))
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("tanh backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not a.requires_grad:
            return
        a._accum(out.grad * (1.0 - t * t))
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("gelu backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not a.requires_grad:
            return
        pdf = np.exp(-0.5 * x * x) / np.sqrt(2.0 * np.pi)
        a._accum(out.grad * (cdf + x * pdf))
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("softmax backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not a.requires_grad:
            return
        g = out.grad
        a._accum(s * (g - (g * s).sum(axis=axis, keepdims=True)))
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("log_softmax backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not a.requires_grad:
            return
        g = out.grad
        a._accum(g - s * g.sum(axis=axis, keepdims=True))
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)
Now the extra activations (softplus, silu, elu, mish, hardtanh, var, std, cumsum):

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("softplus backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not a.requires_grad:
            return
        a._accum(out.grad * (1.0 / (1.0 + np.exp(-bx))))
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("silu backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not a.requires_grad:
            return
        a._accum(out.grad * (sig + a.data * sig * (1.0 - sig)))
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("elu backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not a.requires_grad:
            return
        a._accum(out.grad * np.where(x > 0.0, 1.0, al * ex))
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("mish backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not a.requires_grad:
            return
        sig = 1.0 / (1.0 + np.exp(-x))
        a._accum(out.grad * (t + x * (1.0 - t * t) * sig))
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("hardtanh backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not a.requires_grad:
            return
        mask = (a.data > lo) & (a.data < hi)
        a._accum(out.grad * mask)
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("var backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not a.requires_grad:
            return
        g = out.grad
        if axis is not None and not keepdims:
            axes = (axis,) if isinstance(axis, int) else tuple(axis)
            axes = tuple(ax % a.data.ndim for ax in axes)
            g = np.expand_dims(g, axes)
        denom = n - ddof
        a._accum(g * (2.0 / denom) * (a.data - mu))
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("std backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not a.requires_grad:
            return
        g = out.grad
        if axis is not None and not keepdims:
            axes = (axis,) if isinstance(axis, int) else tuple(axis)
            axes = tuple(ax % a.data.ndim for ax in axes)
            g = np.expand_dims(g, axes)
        a._accum(g * (a.data - mu) / (n * skeep))
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("cumsum backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not a.requires_grad:
            return
        g = out.grad
        rev = np.flip(np.cumsum(np.flip(g, axis=axis), axis=axis), axis=axis)
        a._accum(rev)
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)
Now the generic losses (mse, cross_entropy):

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("mse_loss backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not pred.requires_grad:
            return
        pred._accum(out.grad * 2.0 * diff / n)
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("cross_entropy backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not logits.requires_grad:
            return
        y = np.zeros_like(sm)
        y[np.arange(n), t] = 1.0
        logits._accum(out.grad * (sm - y) / n)
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)
Now the robustness losses:

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("group_weighted_ce backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not logits.requires_grad:
            return
        y = np.zeros_like(sm)
        y[np.arange(n), t] = 1.0
        g = (sm - y) * scale[:, None]
        logits._accum(out.grad * g)
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("reweighted_ce backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not logits.requires_grad:
            return
        y = np.zeros_like(sm)
        y[np.arange(n), t] = 1.0
        g = (sm - y) * (w / wsum)[:, None]
        logits._accum(out.grad * g)
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("group_dro_loss backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not logits.requires_grad:
            return
        y = np.zeros_like(sm)
        y[np.arange(n), t] = 1.0
        g = (sm - y) * scale[:, None]
        logits._accum(out.grad * g)
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("logit_adjusted_ce backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not logits.requires_grad:
            return
        y = np.zeros_like(sm)
        y[np.arange(n), t] = 1.0
        logits._accum(out.grad * (sm - y) / n)
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("focal_loss backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not logits.requires_grad:
            return
        y = np.zeros_like(sm)
        y[np.arange(n), t] = 1.0
        omp = 1.0 - p
        dfldp = g * (omp ** (g - 1.0)) * np.log(pc) - (omp ** g) / pc
        coef = dfldp * p  # (N,)
        grad = coef[:, None] * (y - sm) / n
        logits._accum(out.grad * grad)
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("irm_penalty backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not logits.requires_grad:
            return
        sx = (sm * x).sum(axis=-1, keepdims=True)   # <s_i, x_i> (N,1)
        dgw = ((sm - y) + sm * (x - sx)) / n
        grad = 2.0 * grad_w * dgw
        logits._accum(out.grad * grad)
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("gce_loss backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not logits.requires_grad:
            return
        y = np.zeros_like(sm)
        y[np.arange(n), t] = 1.0
        coef = -(pc ** qf)   # (N,)
        grad = coef[:, None] * (y - sm) / n
        logits._accum(out.grad * grad)
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("vrex_penalty backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not r.requires_grad:
            return
        grad = (2.0 / K) * (rd - mu)
        r._accum(out.grad * grad.reshape(r.data.shape))
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("ldam_loss backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not logits.requires_grad:
            return
        y = np.zeros_like(sm)
        y[np.arange(n), t] = 1.0
        logits._accum(out.grad * sc * (sm - y) / n)
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("spectral_decoupling backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not logits.requires_grad:
            return
        logits._accum(out.grad * lm * x / n)
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("layernorm backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None:
            return
        go = out.grad
        red = tuple(range(go.ndim - 1))
        if gamma.requires_grad:
            gamma._accum((go * xhat).sum(axis=red))
        if beta.requires_grad:
            beta._accum(go.sum(axis=red))
        if a.requires_grad:
            gxhat = go * gamma.data
            m1 = gxhat.mean(axis=-1, keepdims=True)
            m2 = (gxhat * xhat).mean(axis=-1, keepdims=True)
            dx = inv * (gxhat - m1 - xhat * m2)
            a._accum(dx)
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("batchnorm backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None:
            return
        go = out.grad
        if gamma.requires_grad:
            gamma._accum((go * xhat).sum(axis=0))
        if beta.requires_grad:
            beta._accum(go.sum(axis=0))
        if a.requires_grad:
            gxhat = go * gamma.data
            m1 = gxhat.mean(axis=0, keepdims=True)
            m2 = (gxhat * xhat).mean(axis=0, keepdims=True)
            dx = inv * (gxhat - m1 - xhat * m2)
            a._accum(dx)
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("batchnorm2d backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None:
            return
        go = out.grad
        if gamma.requires_grad:
            gamma._accum((go * xhat).sum(axis=(0, 2, 3)))
        if beta.requires_grad:
            beta._accum(go.sum(axis=(0, 2, 3)))
        if x.requires_grad:
            gxhat = go * gamma.data.reshape(1, C, 1, 1)
            if training:
                m1 = gxhat.sum(axis=(0, 2, 3), keepdims=True) / m
                m2 = (gxhat * xhat).sum(axis=(0, 2, 3), keepdims=True) / m
                dx = inv * (gxhat - m1 - xhat * m2)
            else:
                dx = gxhat * inv
            x._accum(dx)
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("rms_norm backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None:
            return
        go = out.grad
        if gamma.requires_grad:
            red = tuple(range(go.ndim - 1))
            gamma._accum((go * xhat).sum(axis=red))
        if a.requires_grad:
            gy = go * gamma.data
            s = (gy * x).sum(axis=-1, keepdims=True)
            dx = r * gy - (r ** 3 / D) * x * s
            a._accum(dx)
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("groupnorm2d backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None:
            return
        go = out.grad
        if gamma.requires_grad:
            gamma._accum((go * xhat).sum(axis=(0, 2, 3)))
        if beta.requires_grad:
            beta._accum(go.sum(axis=(0, 2, 3)))
        if x.requires_grad:
            gxhat = (go * g_).reshape(N, G, m)
            xhat_g = xhat.reshape(N, G, m)
            m1 = gxhat.sum(axis=2, keepdims=True) / m
            m2 = (gxhat * xhat_g).sum(axis=2, keepdims=True) / m
            dxg = inv * (gxhat - m1 - xhat_g * m2)
            x._accum(dxg.reshape(N, C, H, W))
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("conv2d backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None:
            return
        dop = out.grad.reshape(N, Cout, OH * OW)
        if bias.requires_grad:
            bias._accum(dop.sum(axis=(0, 2)))
        if weight.requires_grad:
            dWm = np.einsum("nop,nkp->ok", dop, cols)
            weight._accum(dWm.reshape(Cout, Cin, kh, kw))
        if x.requires_grad:
            dcols = np.einsum("ok,nop->nkp", Wm, dop)
            dcols = dcols.reshape(N, Cin, kh, kw, OH, OW)
            H, W = x.data.shape[2], x.data.shape[3]
            xpg = np.zeros((N, Cin, H + 2 * pad, W + 2 * pad), np.float64)
            for i in range(kh):
                for j in range(kw):
                    xpg[:, :, i:i + st * OH:st, j:j + st * OW:st] += dcols[:, :, i, j, :, :]
            if pad:
                dx = xpg[:, :, pad:pad + H, pad:pad + W]
            else:
                dx = xpg
            x._accum(dx)
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("maxpool2d backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not x.requires_grad:
            return
        mexp = outd[:, :, :, None, :, None]
        mask = (xr == mexp)
        cnt = mask.sum(axis=(3, 5), keepdims=True)
        go = out.grad[:, :, :, None, :, None]
        gxr = mask * go / cnt
        x._accum(gxr.reshape(N, C, H, W))
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("maxpool2d_stride backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not x.requires_grad:
            return
        mexp = outd[:, :, None, None, :, :]
        mask = (win == mexp)
        cnt = mask.sum(axis=(2, 3), keepdims=True)
        go = out.grad[:, :, None, None, :, :]
        gwin = mask * go / cnt
        xpg = np.zeros((N, C, Hp, Wp), np.float64)
        for i in range(k):
            for j in range(k):
                xpg[:, :, i:i + st * OH:st, j:j + st * OW:st] += gwin[:, :, i, j, :, :]
        if pad:
            dx = xpg[:, :, pad:pad + H, pad:pad + W]
        else:
            dx = xpg
        x._accum(dx)
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("avgpool2d backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not x.requires_grad:
            return
        go = out.grad[:, :, :, None, :, None]
        gxr = np.broadcast_to(go / (k * k), (N, C, H // k, k, W // k, k))
        x._accum(gxr.reshape(N, C, H, W).copy())
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("global_avg_pool backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not x.requires_grad:
            return
        go = out.grad[:, :, None, None]
        x._accum(np.broadcast_to(go / (H * W), (N, C, H, W)).copy())
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("embedding backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not weight.requires_grad:
            return
        gz = np.zeros_like(weight.data)
        np.add.at(gz, idx, out.grad)
        weight._accum(gz)
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)
Now dropout (both the eval no-op and train paths):

/app/submission/autograd.py

− removed
        def _bw_id():
            raise NotImplementedError("dropout backward")  # TODO
        out._backward = _bw_id
        return out
+ added
        def _bw_id():
            if out.grad is None or not a.requires_grad:
                return
            a._accum(out.grad)
        out._backward = _bw_id
        return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/autograd.py

− removed
    def _bw():
        raise NotImplementedError("dropout backward")  # TODO
    out._backward = _bw
    return out
+ added
    def _bw():
        if out.grad is None or not a.requires_grad:
            return
        a._accum(out.grad * keep)
    out._backward = _bw
    return out

contents
The file /app/submission/autograd.py has been updated successfully. (file state is current in your context , no need to Read it back)
Now let me run the autograd_grads checks to verify the autograd engine:

Run autograd grad checks

shell
OMP_NUM_THREADS=1 python3 run_checks.py --only autograd_grads 2>&1 | tail -40
output
grad/hardtanh                              OK    (max_abs=1.57e-11)
  grad/var_axis                              OK    (max_abs=3.14e-11)
  grad/std_axis                              OK    (max_abs=3.54e-11)
  grad/cumsum                                OK    (max_abs=1.14e-10)
  grad/maxpool2d_stride                      OK    (max_abs=7.86e-10)
  grad/layernorm_x                           OK  
  grad/batchnorm1d_x                         OK  
  grad/embedding                             OK  
  grad/mse_loss                              OK  
  grad/cross_entropy                         OK  
  grad/conv2d_x                              OK  
  grad/conv2d_weight                         OK  
  grad/conv2d_bias                           OK  
  grad/conv2d_x_pad0                         OK  
  grad/batchnorm2d_x                         OK  
  grad/batchnorm2d_gamma                     OK  
  grad/batchnorm2d_beta                      OK  
  grad/batchnorm2d_x_eval                    OK  
  grad/nn.Linear_x                           FAIL  (raised NotImplementedError: forward)
  grad/nn.Conv2d_x                           FAIL  (raised NotImplementedError: forward)
  grad/nn.LayerNorm_x                        FAIL  (raised NotImplementedError: forward)
  grad/nn.BatchNorm1d_x                      FAIL  (raised NotImplementedError: forward)
  grad/CNN_grad_classifier.weight            FAIL  (raised NotImplementedError: forward)
  grad/CNN_grad_embed.weight                 FAIL  (rai
…[truncated 1123 chars]
All autograd ops pass. Let me verify the top of the output too:

Check for non-forward failures

shell
OMP_NUM_THREADS=1 python3 run_checks.py --only autograd_grads 2>&1 | grep -c "OK"; OMP_NUM_THREADS=1 python3 run_checks.py --only autograd_grads 2>&1 | grep "FAIL" | grep -v "forward"
output
67
All autograd backward bodies are correct. Now let me implement `nn.py` forwards. Let me start with the core layers:

/app/submission/nn.py

− removed
    def forward(self, x: Tensor) -> Tensor:
        # TODO: implement (compose ag.* ops). See the docstring/contract.
        raise NotImplementedError("forward")
    def named_params(self):
        d = {"weight": self.weight}
+ added
    def forward(self, x: Tensor) -> Tensor:
        out = ag.matmul(x, self.weight)
        if self.bias is not None:
            out = ag.add(out, self.bias)
        return out
    def named_params(self):
        d = {"weight": self.weight}

contents
The file /app/submission/nn.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/nn.py

− removed
    def forward(self, x: Tensor) -> Tensor:
        # TODO: implement (compose ag.* ops). See the docstring/contract.
        raise NotImplementedError("forward")
    def named_params(self):
        return {"weight": self.weight, "bias": self.bias}
+ added
    def forward(self, x: Tensor) -> Tensor:
        return ag.conv2d(x, self.weight, self.bias, pad=self.pad, stride=1)
    def named_params(self):
        return {"weight": self.weight, "bias": self.bias}

contents
The file /app/submission/nn.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/nn.py

− removed
    def forward(self, x: Tensor, training: bool = True) -> Tensor:
        # TODO: implement (compose ag.* ops). See the docstring/contract.
        raise NotImplementedError("forward")
    def named_params(self):
        return {"gamma": self.gamma, "beta": self.beta}

    def buffers(self):
+ added
    def forward(self, x: Tensor, training: bool = True) -> Tensor:
        return ag.batchnorm2d(x, self.gamma, self.beta,
                              self.running_mean, self.running_var,
                              training=training, momentum=self.momentum, eps=self.eps)
    def named_params(self):
        return {"gamma": self.gamma, "beta": self.beta}

    def buffers(self):

contents
The file /app/submission/nn.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/nn.py

− removed
    def forward(self, x: Tensor) -> Tensor:
        # TODO: implement (compose ag.* ops). See the docstring/contract.
        raise NotImplementedError("forward")
    def named_params(self):
        return {"gamma": self.gamma, "beta": self.beta}


class LayerNorm(Module):
+ added
    def forward(self, x: Tensor) -> Tensor:
        return ag.batchnorm(x, self.gamma, self.beta, eps=self.eps)
    def named_params(self):
        return {"gamma": self.gamma, "beta": self.beta}


class LayerNorm(Module):

contents
The file /app/submission/nn.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/nn.py

− removed
    def forward(self, x: Tensor) -> Tensor:
        # TODO: implement (compose ag.* ops). See the docstring/contract.
        raise NotImplementedError("forward")
    def named_params(self):
        return {"gamma": self.gamma, "beta": self.beta}


class Dropout(Module):
+ added
    def forward(self, x: Tensor) -> Tensor:
        return ag.layernorm(x, self.gamma, self.beta, eps=self.eps)
    def named_params(self):
        return {"gamma": self.gamma, "beta": self.beta}


class Dropout(Module):

contents
The file /app/submission/nn.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/nn.py

− removed
    def forward(self, x: Tensor, training: bool = False, rng=None) -> Tensor:
        # TODO: implement (compose ag.* ops). See the docstring/contract.
        raise NotImplementedError("forward")
    def named_params(self):
        return {}


class AvgPool2d(Module):
+ added
    def forward(self, x: Tensor, training: bool = False, rng=None) -> Tensor:
        return ag.dropout(x, self.p, training, rng)
    def named_params(self):
        return {}


class AvgPool2d(Module):

contents
The file /app/submission/nn.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/nn.py

− removed
    def forward(self, x: Tensor) -> Tensor:
        # TODO: implement (compose ag.* ops). See the docstring/contract.
        raise NotImplementedError("forward")
    def named_params(self):
        return {}


class MaxPool2d(Module):
+ added
    def forward(self, x: Tensor) -> Tensor:
        return ag.avgpool2d(x, self.k)
    def named_params(self):
        return {}


class MaxPool2d(Module):

contents
The file /app/submission/nn.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/nn.py

− removed
    def forward(self, x: Tensor) -> Tensor:
        # TODO: implement (compose ag.* ops). See the docstring/contract.
        raise NotImplementedError("forward")
    def named_params(self):
        return {}


class RMSNorm(Module):
+ added
    def forward(self, x: Tensor) -> Tensor:
        return ag.maxpool2d(x, self.k)
    def named_params(self):
        return {}


class RMSNorm(Module):

contents
The file /app/submission/nn.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/nn.py

− removed
    def forward(self, x: Tensor) -> Tensor:
        # TODO: implement (compose ag.rms_norm). See the docstring/contract.
        raise NotImplementedError("forward")

    def named_params(self):
        return {"gamma": self.gamma}
+ added
    def forward(self, x: Tensor) -> Tensor:
        return ag.rms_norm(x, self.gamma, eps=self.eps)

    def named_params(self):
        return {"gamma": self.gamma}

contents
The file /app/submission/nn.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/nn.py

− removed
    def forward(self, x: Tensor) -> Tensor:
        # TODO: implement (compose ag.groupnorm2d). See the docstring/contract.
        raise NotImplementedError("forward")

    def named_params(self):
        return {"gamma": self.gamma, "beta": self.beta}
+ added
    def forward(self, x: Tensor) -> Tensor:
        return ag.groupnorm2d(x, self.gamma, self.beta, self.num_groups, eps=self.eps)

    def named_params(self):
        return {"gamma": self.gamma, "beta": self.beta}

contents
The file /app/submission/nn.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/nn.py

− removed
    def forward(self, X, training: bool = True) -> Tensor:
        # TODO: implement (stem->gn0->silu; then 2 residual blocks
        #   r=h; h=silu(b*n1(b*c1(h))); h=b*n2(b*c2(h)); h=silu(h + r);
        #   then strided downsample via ag.conv2d(h, down.weight, down.bias, pad=1, stride=2) + silu;
        #   then global-avg-pool over axes (2,3); then the linear head). Compose ag.* ops.
        raise NotImplementedError("forward")
+ added
    def forward(self, X, training: bool = True) -> Tensor:
        h = X if isinstance(X, Tensor) else Tensor(X)
        h = ag.silu(self.gn0(self.stem(h)))
        # block 1
        r = h
        h = ag.silu(self.b1n1(self.b1c1(h)))
        h = self.b1n2(self.b1c2(h))
        h = ag.silu(ag.add(h, r))
        # block 2
        r = h
        h = ag.silu(self.b2n1(self.b2c1(h)))
        h = self.b2n2(self.b2c2(h))
        h = ag.silu(ag.add(h, r))
        # strided downsample
        h = ag.silu(ag.conv2d(h, self.down.weight, self.down.bias, pad=1, stride=2))
        h = ag.global_avg_pool(h)
        return self.head(h)

contents
The file /app/submission/nn.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/nn.py

− removed
    def featurize(self, X, training: bool = True) -> Tensor:
        # TODO: implement (compose ag.* ops). See the docstring/contract.
        raise NotImplementedError("featurize")
    def forward(self, X, training: bool = True) -> Tensor:
        # TODO: implement (compose ag.* ops). See the docstring/contract.
        raise NotImplementedError("forward")
+ added
    def featurize(self, X, training: bool = True) -> Tensor:
        h = X if isinstance(X, Tensor) else Tensor(X)
        h = ag.maxpool2d(ag.relu(self.bn1(self.conv1(h), training=training)), 2)
        h = ag.maxpool2d(ag.relu(self.bn2(self.conv2(h), training=training)), 2)
        h = ag.relu(self.bn3(self.conv3(h), training=training))
        h = ag.global_avg_pool(h)
        h = ag.relu(self.embed(h))
        return h
    def forward(self, X, training: bool = True) -> Tensor:
        return self.classifier(self.featurize(X, training=training))

contents
The file /app/submission/nn.py has been updated successfully. (file state is current in your context , no need to Read it back)
Now MLP, ResidualMLP, TinyConvNet forwards:

/app/submission/nn.py

− removed
    def forward(self, x) -> Tensor:
        # TODO: implement (compose ag.* ops). See the docstring/contract.
        raise NotImplementedError("forward")
    def named_params(self) -> Dict[str, Tensor]:
        d: Dict[str, Tensor] = {}
        for i, lin in enumerate(self.layers):
+ added
    def forward(self, x) -> Tensor:
        h = x if isinstance(x, Tensor) else Tensor(x)
        for i, lin in enumerate(self.layers):
            h = lin(h)
            if i < len(self.layers) - 1:
                h = ag.relu(h)
        return h
    def named_params(self) -> Dict[str, Tensor]:
        d: Dict[str, Tensor] = {}
        for i, lin in enumerate(self.layers):

contents
The file /app/submission/nn.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/nn.py

− removed
    def forward(self, x) -> Tensor:
        # TODO: implement (compose ag.* ops). See the docstring/contract.
        raise NotImplementedError("forward")
    def named_params(self) -> Dict[str, Tensor]:
        d: Dict[str, Tensor] = {}
        for k, v in self.proj_in.named_params().items():
            d[f"proj_in.{k}"] = v
+ added
    def forward(self, x) -> Tensor:
        h = x if isinstance(x, Tensor) else Tensor(x)
        h = self.proj_in(h)
        for blk in self.blocks:
            y = blk["ln"](h)
            y = blk["fc1"](y)
            y = ag.gelu(y)
            y = blk["fc2"](y)
            h = ag.add(h, y)
        return self.proj_out(h)
    def named_params(self) -> Dict[str, Tensor]:
        d: Dict[str, Tensor] = {}
        for k, v in self.proj_in.named_params().items():
            d[f"proj_in.{k}"] = v

contents
The file /app/submission/nn.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/nn.py

− removed
    def forward(self, X, training: bool = True) -> Tensor:
        # TODO: implement (compose ag.* ops). See the docstring/contract.
        raise NotImplementedError("forward")
    def named_params(self) -> Dict[str, Tensor]:
        d: Dict[str, Tensor] = {}
        for name in ("conv1", "bn1", "conv2", "bn2", "head"):
+ added
    def forward(self, X, training: bool = True) -> Tensor:
        h = X if isinstance(X, Tensor) else Tensor(X)
        h = ag.avgpool2d(ag.relu(self.bn1(self.conv1(h), training=training)), 2)
        h = ag.maxpool2d(ag.relu(self.bn2(self.conv2(h), training=training)), 2)
        N = h.data.shape[0]
        h = ag.reshape(h, (N, self.W * 2 * self.side * self.side))
        return self.head(h)
    def named_params(self) -> Dict[str, Tensor]:
        d: Dict[str, Tensor] = {}
        for name in ("conv1", "bn1", "conv2", "bn2", "head"):

contents
The file /app/submission/nn.py has been updated successfully. (file state is current in your context , no need to Read it back)
Now the robustness machinery helpers:

/app/submission/nn.py

− removed
    balanced-group / DFR weighting). If ``n_groups`` is None it is inferred as max(group_ids)+1."""
    # TODO: implement (numpy only). See docstring.
    raise NotImplementedError("balanced_group_weights")
+ added
    balanced-group / DFR weighting). If ``n_groups`` is None it is inferred as max(group_ids)+1."""
    gids = np.asarray(group_ids).astype(np.int64).reshape(-1)
    if n_groups is None:
        n_groups = int(gids.max()) + 1
    present = np.unique(gids)
    w = np.zeros(int(n_groups), dtype=np.float64)
    w[present] = 1.0 / len(present)
    return w

contents
The file /app/submission/nn.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/nn.py

− removed
    effective number is (1-beta^n_c)/(1-beta) (Cui et al.); beta=0 reduces to inverse-frequency
    1/n_c. Each sample gets its class weight, and the vector is normalized to mean 1."""
    # TODO: implement (numpy only). See docstring.
    raise NotImplementedError("class_balanced_weights")
+ added
    effective number is (1-beta^n_c)/(1-beta) (Cui et al.); beta=0 reduces to inverse-frequency
    1/n_c. Each sample gets its class weight, and the vector is normalized to mean 1."""
    t = np.asarray(targets).astype(np.int64).reshape(-1)
    if n_classes is None:
        n_classes = int(t.max()) + 1
    counts = np.bincount(t, minlength=int(n_classes)).astype(np.float64)
    cw = np.zeros(int(n_classes), dtype=np.float64)
    nz = counts > 0
    if beta == 0.0:
        cw[nz] = 1.0 / counts[nz]
    else:
        eff = (1.0 - beta ** counts[nz]) / (1.0 - beta)
        cw[nz] = 1.0 / eff
    w = cw[t]
    w = w / w.mean()
    return w

contents
The file /app/submission/nn.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/nn.py

− removed
    vector. Empty classes get log(eps)."""
    # TODO: implement (numpy only). See docstring.
    raise NotImplementedError("log_class_prior")
+ added
    vector. Empty classes get log(eps)."""
    t = np.asarray(targets).astype(np.int64).reshape(-1)
    if n_classes is None:
        n_classes = int(t.max()) + 1
    counts = np.bincount(t, minlength=int(n_classes)).astype(np.float64)
    N = t.size
    prior = counts / N
    out = np.where(prior > 0, np.log(np.maximum(prior, eps)), np.log(eps))
    return out

contents
The file /app/submission/nn.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/nn.py

− removed
    Returns a length-``n_classes`` vector."""
    # TODO: implement (numpy only). See docstring.
    raise NotImplementedError("ldam_margins")
+ added
    Returns a length-``n_classes`` vector."""
    t = np.asarray(targets).astype(np.int64).reshape(-1)
    if n_classes is None:
        n_classes = int(t.max()) + 1
    counts = np.bincount(t, minlength=int(n_classes)).astype(np.float64)
    m = np.zeros(int(n_classes), dtype=np.float64)
    nz = counts > 0
    m[nz] = counts[nz] ** (-0.25)
    mx = m[nz].max() if nz.any() else 1.0
    m[nz] = m[nz] * (max_margin / mx)
    return m

contents
The file /app/submission/nn.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/nn.py

− removed
    the PRESENT classes. Returns a length-``n_classes`` per-CLASS weight vector (NOT per-sample)."""
    # TODO: implement (numpy only). See docstring.
    raise NotImplementedError("effective_number_weights")
+ added
    the PRESENT classes. Returns a length-``n_classes`` per-CLASS weight vector (NOT per-sample)."""
    t = np.asarray(targets).astype(np.int64).reshape(-1)
    if n_classes is None:
        n_classes = int(t.max()) + 1
    counts = np.bincount(t, minlength=int(n_classes)).astype(np.float64)
    w = np.zeros(int(n_classes), dtype=np.float64)
    nz = counts > 0
    eff = (1.0 - beta ** counts[nz]) / (1.0 - beta)
    w[nz] = 1.0 / eff
    w[nz] = w[nz] / w[nz].mean()
    return w

contents
The file /app/submission/nn.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/nn.py

− removed
    def update(self, group_losses, present=None):
        # TODO: implement the masked EMA update (see docstring). Return self.l.copy().
        raise NotImplementedError("EMAGroupLoss.update")

    def worst_group(self):
        # TODO: implement (argmax of the current EMA). See docstring.
        raise NotImplementedError("EMAGroupLoss.worst_group")
+ added
    def update(self, group_losses, present=None):
        gl = np.asarray(group_losses, dtype=np.float64).reshape(-1)
        if present is None:
            mask = np.ones(self.n_groups, dtype=bool)
        else:
            mask = np.asarray(present, dtype=bool).reshape(-1)
        for k in range(self.n_groups):
            if not mask[k]:
                continue
            if not self._init[k]:
                self.l[k] = gl[k]
                self._init[k] = True
            else:
                self.l[k] = self.beta * self.l[k] + (1.0 - self.beta) * gl[k]
        return self.l.copy()

    def worst_group(self):
        return int(np.argmax(self.l))

contents
The file /app/submission/nn.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/nn.py

− removed
    def update(self, group_losses):
        # TODO: exponentiated-gradient update of self.q on group_losses; renormalize.
        raise NotImplementedError("GroupDROState.update")
    def weights(self):
+ added
    def update(self, group_losses):
        gl = np.asarray(group_losses, dtype=np.float64).reshape(-1)
        self.q = self.q * np.exp(self.eta_q * gl)
        self.q = self.q / self.q.sum()
        return self.q.copy()
    def weights(self):

contents
The file /app/submission/nn.py has been updated successfully. (file state is current in your context , no need to Read it back)
Now let me run nn_forward, robust, and robust2 checks:

Run nn/robust checks

shell
OMP_NUM_THREADS=1 python3 run_checks.py --only nn_forward 2>&1 | tail -8; echo "===ROBUST==="; OMP_NUM_THREADS=1 python3 run_checks.py --only robust 2>&1 | tail -5; echo "===ROBUST2==="; OMP_NUM_THREADS=1 python3 run_checks.py --only robust2 2>&1 | tail -5
output
fwd/MLP_shape                              OK  
  fwd/ResidualMLP_shape                      OK  
  fwd/TinyConvNet_shape                      OK  

----------------------------------------------------------------------
nn_forward 21/21
TOTAL  21/21 public checks passing
All public checks pass. Now make sure model.npz clears the held-out worst-group accuracy threshold; the grader re-checks with DIFFERENT seeds.
===ROBUST===

----------------------------------------------------------------------
robust 13/13
TOTAL  13/13 public checks passing
All public checks pass. Now make sure model.npz clears the held-out worst-group accuracy threshold; the grader re-checks with DIFFERENT seeds.
===ROBUST2===

----------------------------------------------------------------------
robust2 8/8
TOTAL  8/8 public checks passing
All public checks pass. Now make sure model.npz clears the held-out worst-group accuracy threshold; the grader re-checks with DIFFERENT seeds.
Now the autograd grad checks should all pass too (nn forwards done). Let me do optim.py and data.py:

/app/submission/optim.py

− removed
    def step(self):
        # TODO: implement the SGD update (see module docstring). Update p.data in place.
        raise NotImplementedError("SGD.step")
+ added
    def step(self):
        for i, p in enumerate(self.params):
            if p.grad is None:
                continue
            g = p.grad + self.weight_decay * p.data
            self._v[i] = self.momentum * self._v[i] + g
            v = self._v[i]
            upd = (g + self.momentum * v) if self.nesterov else v
            p.data -= self.lr * upd

contents
The file /app/submission/optim.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/optim.py

− removed
    def step(self):
        # TODO: implement the Adagrad update (see module docstring). Update p.data in place.
        raise NotImplementedError("Adagrad.step")
+ added
    def step(self):
        for i, p in enumerate(self.params):
            if p.grad is None:
                continue
            g = p.grad + self.weight_decay * p.data
            self._s[i] = self._s[i] + g * g
            p.data -= self.lr * g / (np.sqrt(self._s[i]) + self.eps)

contents
The file /app/submission/optim.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/optim.py

− removed
    def step(self):
        # TODO: implement the RMSprop update (see module docstring). Update p.data in place.
        raise NotImplementedError("RMSprop.step")
+ added
    def step(self):
        for i, p in enumerate(self.params):
            if p.grad is None:
                continue
            g = p.grad + self.weight_decay * p.data
            self._s[i] = self.alpha * self._s[i] + (1 - self.alpha) * (g * g)
            p.data -= self.lr * g / (np.sqrt(self._s[i]) + self.eps)

contents
The file /app/submission/optim.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/optim.py

− removed
    def step(self):
        # TODO: implement the Adam update (see module docstring). Update p.data in place.
        raise NotImplementedError("Adam.step")
+ added
    def step(self):
        self.t += 1
        for i, p in enumerate(self.params):
            if p.grad is None:
                continue
            g = p.grad + self.weight_decay * p.data
            self._m[i] = self.b1 * self._m[i] + (1 - self.b1) * g
            self._v[i] = self.b2 * self._v[i] + (1 - self.b2) * (g * g)
            mhat = self._m[i] / (1 - self.b1 ** self.t)
            vhat = self._v[i] / (1 - self.b2 ** self.t)
            p.data -= self.lr * mhat / (np.sqrt(vhat) + self.eps)

contents
The file /app/submission/optim.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/optim.py

− removed
    def step(self):
        # TODO: implement the AdamW update (see module docstring). Update p.data in place.
        raise NotImplementedError("AdamW.step")
+ added
    def step(self):
        self.t += 1
        for i, p in enumerate(self.params):
            if p.grad is None:
                continue
            g = p.grad
            self._m[i] = self.b1 * self._m[i] + (1 - self.b1) * g
            self._v[i] = self.b2 * self._v[i] + (1 - self.b2) * (g * g)
            mhat = self._m[i] / (1 - self.b1 ** self.t)
            vhat = self._v[i] / (1 - self.b2 ** self.t)
            p.data -= self.lr * (mhat / (np.sqrt(vhat) + self.eps) + self.weight_decay * p.data)

contents
The file /app/submission/optim.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/optim.py

− removed
    def step(self):
        # TODO: implement the Adamax update (see module docstring). Update p.data in place.
        raise NotImplementedError("Adamax.step")
+ added
    def step(self):
        self.t += 1
        for i, p in enumerate(self.params):
            if p.grad is None:
                continue
            g = p.grad + self.weight_decay * p.data
            self._m[i] = self.b1 * self._m[i] + (1 - self.b1) * g
            self._u[i] = np.maximum(self.b2 * self._u[i], np.abs(g))
            p.data -= (self.lr / (1 - self.b1 ** self.t)) * self._m[i] / (self._u[i] + self.eps)

contents
The file /app/submission/optim.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/optim.py

− removed
    def step(self):
        # TODO: implement the NAdam update (see module docstring). Update p.data in place.
        raise NotImplementedError("NAdam.step")
+ added
    def step(self):
        self.t += 1
        for i, p in enumerate(self.params):
            if p.grad is None:
                continue
            g = p.grad + self.weight_decay * p.data
            self._m[i] = self.b1 * self._m[i] + (1 - self.b1) * g
            self._v[i] = self.b2 * self._v[i] + (1 - self.b2) * (g * g)
            mhat = self._m[i] / (1 - self.b1 ** self.t)
            vhat = self._v[i] / (1 - self.b2 ** self.t)
            mnes = self.b1 * mhat + (1 - self.b1) * g / (1 - self.b1 ** self.t)
            p.data -= self.lr * mnes / (np.sqrt(vhat) + self.eps)

contents
The file /app/submission/optim.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/optim.py

− removed
    def step(self):
        # TODO: implement the Lion update (see module docstring). Update p.data in place.
        raise NotImplementedError("Lion.step")
+ added
    def step(self):
        for i, p in enumerate(self.params):
            if p.grad is None:
                continue
            g = p.grad
            upd = np.sign(self.b1 * self._m[i] + (1 - self.b1) * g)
            p.data -= self.lr * (upd + self.weight_decay * p.data)
            self._m[i] = self.b2 * self._m[i] + (1 - self.b2) * g

contents
The file /app/submission/optim.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/optim.py

− removed
    def step(self):
        # TODO: implement the RAdam update (see module docstring). Update p.data in place.
        raise NotImplementedError("RAdam.step")
+ added
    def step(self):
        self.t += 1
        t = self.t
        b1, b2 = self.b1, self.b2
        bc2 = 1 - b2 ** t
        rinf = 2.0 / (1 - b2) - 1
        rt = rinf - 2 * t * (b2 ** t) / bc2
        for i, p in enumerate(self.params):
            if p.grad is None:
                continue
            g = p.grad + self.weight_decay * p.data
            self._m[i] = b1 * self._m[i] + (1 - b1) * g
            self._v[i] = b2 * self._v[i] + (1 - b2) * (g * g)
            mhat = self._m[i] / (1 - b1 ** t)
            if rt > 4:
                l = np.sqrt(bc2 / (self._v[i] + self.eps))
                r = math.sqrt(((rt - 4) * (rt - 2) * rinf) / ((rinf - 4) * (rinf - 2) * rt))
                p.data -= self.lr * mhat * r * l
            else:
                p.data -= self.lr * mhat

contents
The file /app/submission/optim.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/optim.py

− removed
    def step(self):
        # TODO: implement the AdaBelief update (see module docstring). Update p.data in place.
        raise NotImplementedError("AdaBelief.step")
+ added
    def step(self):
        self.t += 1
        for i, p in enumerate(self.params):
            if p.grad is None:
                continue
            g = p.grad
            self._m[i] = self.b1 * self._m[i] + (1 - self.b1) * g
            d = g - self._m[i]
            self._s[i] = self.b2 * self._s[i] + (1 - self.b2) * (d * d) + self.eps
            mhat = self._m[i] / (1 - self.b1 ** self.t)
            shat = self._s[i] / (1 - self.b2 ** self.t)
            p.data -= self.lr * (mhat / (np.sqrt(shat) + self.eps) + self.weight_decay * p.data)

contents
The file /app/submission/optim.py has been updated successfully. (file state is current in your context , no need to Read it back)
Now the grad clippers and schedulers:

/app/submission/optim.py

− removed
    exceeds ``max_norm`` every grad is scaled by ``max_norm / (total_norm + 1e-6)``."""
    # TODO: implement (see docstring).
    raise NotImplementedError("clip_grad_norm")
+ added
    exceeds ``max_norm`` every grad is scaled by ``max_norm / (total_norm + 1e-6)``."""
    total = 0.0
    for p in params:
        if p.grad is not None:
            total += float((p.grad ** 2).sum())
    total = math.sqrt(total)
    if total > max_norm:
        scale = max_norm / (total + 1e-6)
        for p in params:
            if p.grad is not None:
                p.grad = p.grad * scale
    return total

contents
The file /app/submission/optim.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/optim.py

− removed
    """Element-wise gradient clamp to [-clip_value, clip_value] (in place)."""
    # TODO: implement (see docstring).
    raise NotImplementedError("clip_grad_value")
+ added
    """Element-wise gradient clamp to [-clip_value, clip_value] (in place)."""
    for p in params:
        if p.grad is not None:
            p.grad = np.clip(p.grad, -clip_value, clip_value)

contents
The file /app/submission/optim.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/optim.py

− removed
    ``total``. ``step`` is 0-based. Holds at ``min_lr`` past ``total``."""
    # TODO: implement (see docstring).
    raise NotImplementedError("cosine_lr")
+ added
    ``total``. ``step`` is 0-based. Holds at ``min_lr`` past ``total``."""
    if warmup > 0 and step < warmup:
        return base_lr * (step + 1) / warmup
    prog = min(1.0, max(0.0, (step - warmup) / max(1, total - warmup)))
    return min_lr + 0.5 * (base_lr - min_lr) * (1 + math.cos(math.pi * prog))

contents
The file /app/submission/optim.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/optim.py

− removed
    """Linear warmup to ``base_lr`` over ``warmup`` steps, then constant ``base_lr``."""
    # TODO: implement (see docstring).
    raise NotImplementedError("warmup_lr")
+ added
    """Linear warmup to ``base_lr`` over ``warmup`` steps, then constant ``base_lr``."""
    if step < warmup:
        return base_lr * (step + 1) / warmup
    return base_lr

contents
The file /app/submission/optim.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/optim.py

− removed
    """Step decay: lr = base_lr * gamma ** (step // step_size)."""
    # TODO: implement (see docstring).
    raise NotImplementedError("step_lr")
+ added
    """Step decay: lr = base_lr * gamma ** (step // step_size)."""
    return base_lr * (gamma ** (step // step_size))

contents
The file /app/submission/optim.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/optim.py

− removed
    """Exponential decay: lr = base_lr * gamma ** step."""
    # TODO: implement (see docstring).
    raise NotImplementedError("exponential_lr")
+ added
    """Exponential decay: lr = base_lr * gamma ** step."""
    return base_lr * (gamma ** step)

contents
The file /app/submission/optim.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/optim.py

− removed
    ``step >= total`` holds at ``min_lr``. ``step`` is 0-based."""
    # TODO: implement (see docstring).
    raise NotImplementedError("polynomial_lr")
+ added
    ``step >= total`` holds at ``min_lr``. ``step`` is 0-based."""
    if step >= total:
        return min_lr
    return (base_lr - min_lr) * ((1 - step / total) ** power) + min_lr

contents
The file /app/submission/optim.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/optim.py

− removed
    in-cycle step s: lr = min_lr + 0.5*(base_lr-min_lr)*(1+cos(pi*s/T)). ``step`` is 0-based."""
    # TODO: implement (see docstring).
    raise NotImplementedError("cosine_restart_lr")
+ added
    in-cycle step s: lr = min_lr + 0.5*(base_lr-min_lr)*(1+cos(pi*s/T)). ``step`` is 0-based."""
    s = step
    T_ = period
    while s >= T_:
        s -= T_
        T_ *= t_mult
    return min_lr + 0.5 * (base_lr - min_lr) * (1 + math.cos(math.pi * s / max(1, T_)))

contents
The file /app/submission/optim.py has been updated successfully. (file state is current in your context , no need to Read it back)
Now data.py:

/app/submission/data.py

− removed
    """Flatten (y, g) to a single group id y*n_classes + g (int64)."""
    # TODO
    raise NotImplementedError("group_ids")
+ added
    """Flatten (y, g) to a single group id y*n_classes + g (int64)."""
    return (np.asarray(y).astype(np.int64) * int(n_classes) + np.asarray(g).astype(np.int64))

contents
The file /app/submission/data.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/data.py

− removed
    """Yield (Xb, yb, gb) minibatches over a random permutation of the dataset."""
    # TODO
    raise NotImplementedError("iterate")
+ added
    """Yield (Xb, yb, gb) minibatches over a random permutation of the dataset."""
    N = X.shape[0]
    perm = rng.permutation(N)
    for i in range(0, N, batch_size):
        idx = perm[i:i + batch_size]
        yield X[idx], y[idx], g[idx]

contents
The file /app/submission/data.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/data.py

− removed
    """Return (min over (y,g) groups of within-group accuracy, average accuracy, per-group dict)."""
    # TODO
    raise NotImplementedError("worst_group_acc")
+ added
    """Return (min over (y,g) groups of within-group accuracy, average accuracy, per-group dict)."""
    preds = np.asarray(preds).reshape(-1)
    y = np.asarray(y).reshape(-1)
    g = np.asarray(g).reshape(-1)
    gid = group_ids(y, g, n_classes)
    correct = (preds == y)
    avg = float(correct.mean())
    per = {}
    for k in np.unique(gid):
        mask = gid == k
        per[int(k)] = float(correct[mask].mean())
    wga = min(per.values()) if per else 0.0
    return wga, avg, per

contents
The file /app/submission/data.py has been updated successfully. (file state is current in your context , no need to Read it back)

/app/submission/data.py

− removed
    """Boolean mask selecting ~frac of EACH (y,g) group (keeps both slices group-balanced)."""
    # TODO
    raise NotImplementedError("stratified_group_split")
+ added
    """Boolean mask selecting ~frac of EACH (y,g) group (keeps both slices group-balanced)."""
    y = np.asarray(y).reshape(-1)
    g = np.asarray(g).reshape(-1)
    gid = group_ids(y, g, n_classes)
    mask = np.zeros(len(y), dtype=bool)
    for k in np.unique(gid):
        idx = np.where(gid == k)[0]
        rng.shuffle(idx)
        n_sel = int(round(frac * len(idx)))
        mask[idx[:n_sel]] = True
    return mask

contents
The file /app/submission/data.py has been updated successfully. (file state is current in your context , no need to Read it back)
Now let me run the full check suite:

Run full check suite

shell
OMP_NUM_THREADS=1 python3 run_checks.py 2>&1 | tail -12
output
robust2/effective_number_weights           OK    (mean=1.000)
  robust2/ema_group_loss_tracks_worst        OK    (l=[0.112 0.904 0.196])

[data]  3/3
  data/group_ids                             OK    ([ 1  4 11 14])
  data/worst_group_acc                       OK    (wga=0.00 avg=0.80)
  data/stratified_group_split                OK    (selected 33/60)

----------------------------------------------------------------------
autograd_grads 81/81 | nn_forward 21/21 | optim 21/21 | robust 13/13 | robust2 8/8 | data 3/3
TOTAL  147/147 public checks passing
All public checks pass. Now make sure model.npz clears the held-out worst-group accuracy threshold; the grader re-checks with DIFFERENT seeds.
All 147 public checks pass. Let me run the smoke test:

View test.sh

shell
cat test.sh
output
#!/usr/bin/env bash
# Smoke test (NOT the grader): confirms the environment is wired -- numpy imports, the train +
# reweight splits load, and the submission stubs are present. It does NOT check correctness (the
# stubs raise NotImplementedError until you implement them).
set -uo pipefail

python3 - <<'PY'
import numpy as np, os
for f in ("train.npz", "reweight.npz"):
    assert os.path.exists(f"/app/data/{f}"), f"missing /app/data/{f}"
d = np.load("/app/data/train.npz"); r = np.load("/app/data/reweight.npz")
print(f"train X {d['X'].shape} y {d['y'].shape} g {d['g'].shape}; reweight X {r['X'].shape}")
assert r["X"].shape[1:] == d["X"].shape[1:], (r["X"].shape, d["X"].shape)
for f in ("autograd.py", "nn.py", "optim.py", "data.py", "train.py"):
    assert os.path.exists(f"/app/submission/{f}"), f"missing /app/submission/{f}"
assert os.path.exists("/app/run_checks.py"), "missing /app/run_checks.py"
print("submission stubs present:", sorted(os.listdir("/app/submission")))
print("numpy", np.__version__)
PY

# The visible check runner is present + runnable (it exits 1 on the unfilled stub, which is
# expected -- the stubs raise NotImplementedError until you implement them).
python3 /app/run_checks.py --quiet || true
echo "app_test smoke OK (run 'python3 /app/run_checks.py' to test your implementation)"
All checks pass. Now let me write the training recipe (DFR):

/app/submission/train.py

− removed
def main():
    ap = argparse.ArgumentParser()
    ap.add_argument("--train", default="/app/data/train.npz")
    ap.add_argument("--reweight", default="/app/data/reweight.npz")
    ap.add_argument("--out", default="/app/submission/model.npz")
    ap.add_argument("--seed", type=int, default=0)
    args = ap.parse_args()

    # TODO: build a SmallCNN(n_classes, img_size, width=WIDTH, embed_dim=EMBED_DIM), train a
    #       worst-group-robust recipe with your framework (forward -> loss -> backward -> clip ->
    #       optimizer step), then save:
    #           save_checkpoint(args.out, model.state_dict(), n_classes, img_size)
    raise NotImplementedError("implement training and call save_checkpoint")
+ added
def _featurize_np(model, X, batch=256):
    """Compute penultimate features (N, E) in eval mode, batched, as a numpy array."""
    feats = []
    for i in range(0, X.shape[0], batch):
        xb = X[i:i + batch]
        f = model.featurize(xb, training=False)
        feats.append(np.asarray(f.data))
    return np.concatenate(feats, axis=0)


def main():
    ap = argparse.ArgumentParser()
    ap.add_argument("--train", default="/app/data/train.npz")
    ap.add_argument("--reweight", default="/app/data/reweight.npz")
    ap.add_argument("--out", default="/app/submission/model.npz")
    ap.add_argument("--seed", type=int, default=0)
    args = ap.parse_args()

    rng = np.random.default_rng(args.seed)

    Xtr, ytr, gtr = D.load_npz(args.train)
    Xrw, yrw, grw = D.load_npz(args.reweight)
    n_classes = int(max(ytr.max(), yrw.max())) + 1
    img_size = Xtr.shape[-1]
    print(f"n_classes={n_classes} img_size={img_size} Xtr={Xtr.shape} Xrw={Xrw.shape}")

    model = SmallCNN(n_classes=n_classes, img_size=img_size,
                     width=WIDTH, embed_dim=EMBED_DIM, seed=args.seed)

    # ---------------------------------------------------------------- Phase 1: ERM extractor
    params = model.params()
    epochs = 25
    batch = 128
    base_lr = 2e-3
    n = Xtr.shape[0]
    steps_per_epoch = (n + batch - 1) // batch
    total_steps = epochs * steps_per_epoch
    opt = O.AdamW(params, lr=base_lr, weight_decay=1e-4)
    step = 0
    for ep in range(epochs):
        perm = r
…[truncated 3593 chars]

contents
The file /app/submission/train.py has been updated successfully. (file state is current in your context , no need to Read it back)

Run training

shell
cd /app/submission && OMP_NUM_THREADS=1 OPENBLAS_NUM_THREADS=1 MKL_NUM_THREADS=1 timeout 580 python3 train.py 2>&1 | tail -40
Final diff , what the agent changed

No file changes, the agent left the workspace untouched.

Verifier output , the proof behind the reward
tests/test.sh
=== SyncVals verifier (local re-grade of the agent's own checkpoint) ===

COMPONENT CONFORMANCE SUITE: 194/194 cases passed  (all milestones pass: True)
FINAL METRIC: worst-group accuracy = 0.8067  < threshold 0.86

REWARD = 0   (1 iff every component milestone passes AND the sealed held-out metric clears its threshold)

NOTE: the in-sandbox training in the 481MB e2b box was OOM-killed (0-byte checkpoint), so the raw
in-sandbox reward was an infrastructure artifact. This reward is from a faithful LOCAL re-train of the
agent's OWN train.py (24GB, no OOM) with its own default hyperparameters, then re-graded by the real verifier.

Reproduce this trial: git checkout 2f94510 && PYTHONPATH=src python3 scripts/build_site.py , then open trial/trial_d266b06a6b214868. Re-running the agent live requires EVAL_PLATFORM_ENABLE_OAUTH_SMOKE=1 and is non-deterministic.

Trial trial_d266b06a6b214868 · verifier authoritative; classifier explanatory.