arXiv Computation and Language By Nicol\'as Vera Z\'u\~niga

Easy to anticipate, hard to compute: boundary dependence finds the computed outputs that entropy patching misses

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The paper investigates how byte‑level language models that use entropy‑based patching (like BLT) fail to compute certain predictable but value‑dependent positions, such as numbers following an equals sign in math solutions. By introducing a boundary‑dependence signal—measuring the model’s loss when a patch start is removed—they show that this signal, combined with entropy, significantly improves accuracy on computed outputs across various model sizes and budgets. The study demonstrates that entropy alone leaves a systematic blind spot that boundary dependence can fill, leading to higher exact‑match rates on challenging computed tasks.

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