At reasoning depth 16 and 32, GPT-5.6 and Qwen3.5 answer long-context graph questions no better than random guessing
AspireAI community · arXiv (cs.CL)
The needle-in-a-haystack benchmark measures finding small facts in a large input, but existing variants rely on synthetic data, reuse published datasets that risks contamination, depend on manual annotation, and simplify multi-hop reasoning so each step is trivial given the previous one. GraphNIAH is built from real citation relationships among scientific papers published after the evaluated models' knowledge cutoff, with a fully automated pipeline sampling representative subgraphs and converting each into a long-context QA example with a verifiable answer. Evaluating eight LLMs from the GPT-5.6, Gemini-3 and Qwen3.5 families, accuracy falls as questions require longer reasoning paths, and at question depths of 16 and 32 the GPT-5.6 and Qwen3.5 models answer YES/NO questions no better than random guessing, mostly by answering NO. The finding is about multi-step reasoning over long contexts rather than retrieval of a single fact.
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