ME-Decoding from RUC treats LLM token selection as ensemble pruning, beats Top-p across benchmarks

机器之心 · wechat · 2026-09-30

A Renmin University team (advised by Wenlin Dai and Cheng Meng) proposes Mahalanobis-Ensemble Decoding, accepted to EMNLP 2026 Main. Instead of truncating by single-token probability like Top-p/Min-p, it jointly scores confidence and semantic redundancy of the candidate set, greedily growing it with an early stop until the Mahalanobis-Ensemble Score peaks.

Results: highest average accuracy on GSM8K (72.66%) and GPQA (32.96%) across Qwen3-4B, Phi-4-mini and Mistral-7B at temperatures 1.0–2.0, staying robust where truncation methods degrade at high temperature; top AlpacaEval winrate and MT-Bench scores. Gains persist when support size, entropy and cosine similarity are matched, and end-to-end GPU latency rises only 3% over the fastest truncation baseline. Paper: arxiv.org/abs/2609.18723, code open-sourced.

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