Benchmarking LLMs on false closure failures

Plastic-Cell-4497 · reddit · 2026-08-31

The author built a benchmark called CFC targeting a specific LLM failure mode: False Closure, where models reach definite conclusions unjustified by evidence. This includes silently turning UNRESOLVED to TRUE/FALSE, resolving conflicts without rules, and relying on stale evidence.

The test suite includes 100 cases run across four model tracks (1,200 runs). Strong models like Claude and Gemini passed 98.7% semantically, but failed on different cases. The GPT track scored perfectly but was marked as non-independent. The focus is not on the score gap but on the specific reasoning errors that survive high pass rates, inviting feedback from the evaluation community.

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