fix(nn): apply pre-norm and dropout around RowColTransformer attention - #436
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ChrisW09 wants to merge 2 commits into
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fix(nn): apply pre-norm and dropout around RowColTransformer attention#436ChrisW09 wants to merge 2 commits into
ChrisW09 wants to merge 2 commits into
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The attention slots are nn.Sequential(LayerNorm, MultiheadAttention, Dropout), but forward indexed only attn[1], skipping the pre-norm at index 0 and the dropout at index 2. SAINT therefore trained with no normalization before either the column-wise or row-wise attention and no attention-path dropout, and the LayerNorm parameters received no gradients at all. Fixes #416 Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
model._task_model and model._data_module are Optional-typed internals. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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Fixes #416
Problem
RowColTransformer(the backbone SAINT uses) builds each attention slot asnn.Sequential(LayerNorm, MultiheadAttention, Dropout), butforwardcalls only the attention module:SAINT therefore trains with no normalization before either attention block and no attention-path dropout, diverging from the published architecture and risking instability. Verified: the LayerNorm weights inside those Sequentials have
grad is Noneafter a backward pass — they are dead parameters carried in the optimizer.Fix
Apply the full pre-norm → attention → dropout → residual chain for both the column-wise and row-wise attention.
Tests
New
tests/test_saint_attention.pyfits aSAINTRegressor, runs one manual forward/backward, and asserts the attention LayerNorm parameters receive gradients.tests/test_nn_blocks.pypasses unchanged.🤖 Generated with Claude Code