The Complexity of Finding Reset Words in Finite Automata

We study several problems related to finding reset words in deterministic finite automata. In particular, we establish that the problem of deciding whether a shortest reset word has length k is complete for the complexity class DP. This result answers a question posed by Volkov. For the search problems of finding a shortest reset word and the length of a shortest reset word, we establish membership in the complexity classes FPNP and FPNP[log] , respectively. Moreover, we show that both these problems are hard for FPNP[log] . Finally, we observe that computing a reset word of a given length is FNP-complete.

• Type: Journal
• Year: 2010
• Where: CORR
• Authors: Jörg Olschewski, Michael Ummels
• Keywords: Complexity Class Dp, CORR 2010, Deterministic Finite Automata, Education, Shortest Reset Word