Size Reduction of Multitape Automata

Abstract

Several models of multitape automata have been introduced over the years. Here we consider a modified version of the Rabin-Scott model [2] motivated by the needs of developing a string manipulating database system of [1]. We present an algorithm to reduce the size of a multitape automaton in this model. The algorithm uses certain local transformations that change the order in which transitions concerning different tapes occur in the automaton graph, and merge suitable states together into a single state. Although the resulting automaton is not necessarily minimal, the size of the automaton may be reduced considerably as the example below indicates.