English

Going Higher in First-Order Quantifier Alternation Hierarchies on Words

Logic in Computer Science 2017-07-19 v1

Abstract

We investigate quantifier alternation hierarchies in first-order logic on finite words. Levels in these hierarchies are defined by counting the number of quantifier alternations in formulas. We prove that one can decide membership of a regular language in the levels BΣ2\mathcal{B}{\Sigma}_2 (finite boolean combinations of formulas having only one alternation) and Σ3{\Sigma}_3 (formulas having only two alternations and beginning with an existential block). Our proofs work by considering a deeper problem, called separation, which, once solved for lower levels, allows us to solve membership for higher levels.

Keywords

Cite

@article{arxiv.1707.05696,
  title  = {Going Higher in First-Order Quantifier Alternation Hierarchies on Words},
  author = {Thomas Place and Marc Zeitoun},
  journal= {arXiv preprint arXiv:1707.05696},
  year   = {2017}
}

Comments

arXiv admin note: text overlap with arXiv:1404.6832

R2 v1 2026-06-22T20:50:31.255Z