arXiv Computation and Language By Jie Sun, Mao Zheng, Mingyang Song, Qiyong Zhong, Yilin Cheng, Bichuan Feng, Pengfei Liu, Junfeng Fang, Xiang Wang

SimCT: Recovering Lost Supervision for Cross-Tokenizer On-Policy Distillation

Read the original on arXiv Computation and Language →

SimCT is a method for on‑policy distillation that addresses the problem of mismatched tokenizers between teacher and student models. By comparing teacher and student predictions over short multi‑token continuations that both tokenizers can produce, SimCT restores supervision that would otherwise be lost when only exact shared tokens are used. Experiments on mathematical reasoning and code‑generation tasks show consistent improvements over shared‑vocabulary OPD and other cross‑tokenizer baselines, with ablations confirming the gains come from recovering discarded supervision.

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