comparing-weight-shared-recursive-model-against-depth-matched-plain-transformer-code CLM-0034
mechanismsingle paperReviewed by AI

When comparing a weight-shared recursive model against a depth-matched plain transformer on code generation, the ranking read from a single checkpoint can invert during training, because the larger-parameter arm passes its validation optimum and overfits while the parameter-lean recursive arm keeps improving — so a late-epoch "recursion fits better" reading is a degradation artifact, not a capability difference.

Capability: Whether the measurement made the finding

Observed on

~28M-parameter models, instruction-to-Python corpus of ~38k training records, many passes over a fixed corpus (data-constrained repeated-data regime), 40-epoch budget, three seeds;.

Sources

  • Measured: three arms (recursive 20-effective-depth shared 2-layer block, iso-parameter 2-layer, iso-depth 20-layer) trained 40 epochs, 3 seeds, snapshots at 9 epochs. Fit ranking between recursive and iso-depth arms reversed at epochs 8 and 40; iso-depth validation loss bottomed at epoch 20 (1.15) and rose to 1.45 by epoch 40 while training loss fell. Cross-seed spread tight. Only one architecture family, one synthetic corpus, no execution-based correctness metric; [truncated]
Reviewed by AI (Claude Opus 5)Last checked: 2026-09-09Evidence activity: not checked yet
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Notes

Drafted from the paper by a model and filed unreviewed. Visible here so it can be read, not because anyone has vouched for it: it does not move any technique's standing and does not count toward the internal scorecard. Drafted confidence: medium. Falsifier as drafted: Tracking the same matched arms across training on other corpora or scales and finding the fit ranking stable across all checkpoints, so a single arbitrary checkpoint reproduces the validation-optimum ordering. Proposed technique, not catalogued: Trajectory-wide evaluation with per-arm validation-optimum checkpoint selection.