On input-revolving deterministic and nondeterministic finite automata

  • Authors:

  • Suna Bensch;Henning Bordihn;Markus Holzer;Martin Kutrib

  • Affiliations:

  • Institutionen för Datenvetenskap, Umeå Universitet, 901 87 Umeå, Sweden;Institut für Informatik, Universität Potsdam, August-Bebel-Straße 89, 14482 Potsdam, Germany;Institut für Informatik, Universität Giessen Arndtstraße 2, 35392 Giessen, Germany;Institut für Informatik, Universität Giessen Arndtstraße 2, 35392 Giessen, Germany

  • Venue:
  • Information and Computation
  • Year:
  • 2009

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Abstract

We introduce and investigate input-revolving finite automata, which are (nondeterministic) finite state automata with the additional ability to shift the remaining part of the input. Three different modes of shifting are considered, namely revolving to the left, revolving to the right, and circular interchanging. We investigate the computational capacities of these three types of automata and their deterministic variants, comparing any of the six classes of automata with each other and with further classes of well-known automata. In particular, it is shown that nondeterminism is better than determinism, that is, for all three modes of shifting there is a language accepted by the nondeterministic model but not accepted by any deterministic automaton of the same type. Concerning the closure properties most of the deterministic language families studied are not closed under standard operations. For example, we show that the family of languages accepted by deterministic right-revolving finite automata is an anti-AFL which is not closed under reversal and intersection.