MatrAIx Builds a Simulated World of 8.3 Billion Persona Agents Across 1,290 Dimensions — and Releases a 1M Coreset With 91.5% Behavioral Adherence
arXiv 2608.04205, a 93-author effort led by Xiaomin Li, constructs a persona database of 8.3 billion records spanning 1,290 categorical dimensions, plus a Playground with four evaluation environments (Survey, AI Chatbot, Web, App) and 1,010 application tasks across 25+ domains including Commerce, Software, Finance, and Healthcare. They ran 18,189 trials across eight representative tasks using Claude Opus 4.8, GPT 5.5, and Claude Haiku 4.5. The credibility hinge is a 400-trial controlled validation where declared persona behavior was correctly expressed or suppressed in 366 trials (91.5%) — and they released a ~1M-persona coreset (599,847 human-grounded, 400,000 synthetic), which is the part builders can actually use for synthetic user testing. It reached 623 upvotes on HuggingFace Daily Papers.
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