Length Value Model: Scalable Value Pretraining for Token-Level Length Modeling

Apple · 3 months ago · 27

Researchers introduced Length Value Model (LenVM), a framework that predicts remaining generation length at each token step during decoding by treating it as a value estimation problem. On LIFEBench exact length matching, LenVM improved a 7B model's length score from 30.9 to 64.8, and maintained 63 percent accuracy on GSM8K with a 200-token budget compared to 6 percent for baseline methods. This enables better control over generation length-performance tradeoffs and provides interpretable signals about how individual tokens influence reasoning depth.