Succinct representation for (non)deterministic finite automata

Abstract

(Non)-Deterministic finite automata are one of the simplest models of computation studied in automata theory. Here we study them through the lens of succinct data structures. Towards this goal, we design a data structure for any deterministic automaton D having n states over a σ-letter alphabet Σ using (σ−1)nlog⁡n(1+o(1)) bits, that determines, given a string x, whether D accepts x in optimal O(|x|) time. We also consider the case when there are N<σn non-failure transitions, and obtain various time-space trade-offs. Here some of our results are better than the recent work of Cotumaccio and Prezza (SODA 2021). We also exhibit a data structure for non-deterministic automaton N using σn2+n bits that takes O(n2|x|) time for string membership checking. Finally, we also provide time and space efficient algorithms for performing several standard operations on the languages accepted by finite automata.