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Main Authors: Frisoni, Giacomo, Molfetta, Lorenzo, Freddi, Davide, Moro, Gianluca
Format: Preprint
Published: 2026
Subjects:
Online Access:https://arxiv.org/abs/2602.04447
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author Frisoni, Giacomo
Molfetta, Lorenzo
Freddi, Davide
Moro, Gianluca
author_facet Frisoni, Giacomo
Molfetta, Lorenzo
Freddi, Davide
Moro, Gianluca
contents Modern chess language models are dense transformers trained on millions of games played by thousands of high-rated individuals. However, these monolithic networks tend to collapse into mode-averaged behavior, where stylistic boundaries are blurred, and rare but effective strategies are suppressed. To counteract homogenization, we introduce Mixture-of-Masters (MoM), the first chess mixture-of-experts model with small-sized GPT experts emulating world-class grandmasters. For each move, a post-hoc learnable gating network selects the most appropriate persona to channel depending on the game state, allowing MoM to switch its style dynamically, e.g., Tal's offensive vocation or Petrosian's defensive solidity. When evaluated against Stockfish on unseen standard games, MoM outperforms both dense individual expert networks and popular GPT baselines trained on aggregated data, while ensuring generation variety, control, and interpretability.
format Preprint
id arxiv_https___arxiv_org_abs_2602_04447
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Mixture of Masters: Sparse Chess Language Models with Player Routing
Frisoni, Giacomo
Molfetta, Lorenzo
Freddi, Davide
Moro, Gianluca
Machine Learning
Artificial Intelligence
Modern chess language models are dense transformers trained on millions of games played by thousands of high-rated individuals. However, these monolithic networks tend to collapse into mode-averaged behavior, where stylistic boundaries are blurred, and rare but effective strategies are suppressed. To counteract homogenization, we introduce Mixture-of-Masters (MoM), the first chess mixture-of-experts model with small-sized GPT experts emulating world-class grandmasters. For each move, a post-hoc learnable gating network selects the most appropriate persona to channel depending on the game state, allowing MoM to switch its style dynamically, e.g., Tal's offensive vocation or Petrosian's defensive solidity. When evaluated against Stockfish on unseen standard games, MoM outperforms both dense individual expert networks and popular GPT baselines trained on aggregated data, while ensuring generation variety, control, and interpretability.
title Mixture of Masters: Sparse Chess Language Models with Player Routing
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2602.04447