English

Resolving Nondeterminism by Chance

Formal Languages and Automata Theory 2026-04-01 v2

Abstract

History-deterministic automata are those in which nondeterministic choices can be correctly resolved stepwise: there is a strategy to select a continuation of a run given the next input letter so that if the overall input word admits some accepting run, then the constructed run is also accepting. Motivated by checking qualitative properties in probabilistic verification, we consider the setting where the resolver strategy can randomize and only needs to succeed with lower-bounded probability. We study the expressiveness of such stochastically-resolvable automata as well as consider the decision questions of whether a given automaton has this property. In particular, we show that it is undecidable to check if a given NFA is λ\lambda-stochastically resolvable. This problem is decidable for finitely-ambiguous automata. We also present complexity upper and lower bounds for several well-studied classes of automata for which this problem remains decidable.

Keywords

Cite

@article{arxiv.2504.10234,
  title  = {Resolving Nondeterminism by Chance},
  author = {Soumyajit Paul and David Purser and Sven Schewe and Qiyi Tang and Patrick Totzke and Di-De Yen},
  journal= {arXiv preprint arXiv:2504.10234},
  year   = {2026}
}

Comments

Extended version of CONCUR 2025 paper

R2 v1 2026-06-28T22:57:39.397Z