AI and the World's Hard Problems · Theoretical computer science · arXiv · 2026-10-19
Complexity of liveness in ring Petri nets and of halting in chip-firing on simple digraphs
The paper shows that deciding liveness of ring Petri nets is coNP-complete, even for token-conserving rings, and that the halting problem for chip-firing on simple directed graphs is NP-complete, answering a question by Farrell and Levine. The reduction was found by Claude Opus 5.5, which also wrote a first version of the paper. The human authors checked it and revised it iteratively with the model.