One-way reversible multi-head finite automata

Abstract

One-way multi-head finite automata are considered towards their ability to perform reversible computations. It is shown that, for every number k ≥ 1 of heads, there are problems which can be solved by one-way k-head finite automata, but not by any one-way reversible k-head finite automaton. Additionally, a proper head hierarchy is obtained for one-way reversible multi-head finite automata. Finally, decidability problems are considered. It turns out that one-way reversible finite automata with two heads are still a powerful model, since almost all commonly studied problems are not even semidecidable. © 2013 Springer-Verlag Berlin Heidelberg.