Primitivity, Uniform Minimality and State Complexity of Boolean Operations
Abstract
A minimal deterministic finite automaton (DFA) is uniformly minimal if it always remains minimal when the final state set is replaced by a non-empty proper subset of the state set. We prove that a permutation DFA is uniformly minimal if and only if its transition monoid is a primitive group. We use this to study boolean operations on group languages, which are recognized by direct products of permutation DFAs. A direct product cannot be uniformly minimal, except in the trivial case where one of the DFAs in the product is a one-state DFA. However, non-trivial direct products can satisfy a weaker condition we call uniform boolean minimality, where only final state sets used to recognize boolean operations are considered. We give sufficient conditions for a direct product of two DFAs to be uniformly boolean minimal, which in turn gives sufficient conditions for pairs of group languages to have maximal state complexity under all binary boolean operations ("maximal boolean complexity"). In the case of permutation DFAs with one final state, we give necessary and sufficient conditions for pairs of group languages to have maximal boolean complexity. Our results demonstrate a connection between primitive groups and automata with strong minimality properties.
Keywords
Cite
@article{arxiv.1702.00877,
title = {Primitivity, Uniform Minimality and State Complexity of Boolean Operations},
author = {Sylvie Davies},
journal= {arXiv preprint arXiv:1702.00877},
year = {2018}
}
Comments
46 pages, 5 figures. Expanded version published in Theory of Computing Systems (https://doi.org/10.1007/s00224-018-9859-0); also available at http://rdcu.be/JQDs via Springer Nature SharedIt. The present arXiv version corrects errors in the statements and proofs of Theorem 2 and Corollary 3 (these errors are also fixed in the journal version)