Publication details
Describing periodicity in two
-way deterministic finite automata using transformation semigroups
| Basic information | |
|---|---|
| Original title: | Describing periodicity in two -way deterministic finite automata using transformation semigroups |
| Authors: | Michal Kunc, Alexander Okhotin |
| Further information | |
|---|---|
| Citation: | KUNC, Michal and Alexander OKHOTIN. Describing periodicity in
two -way deterministic finite automata using transformation
semigroups. In Giancarlo Mauri, Alberto Leporati. Developments
in Language Theory: 15th International Conference, DLT 2011,
Milan, Italy, July 19 -22, 2011. Proceedings. Berlin: Springer,
2011. p. 324 -336, 13 pp. ISBN 978 -3 -642 -22320 -4.
doi:10.1007/978 -3 -642 -22321 -1_28.Export BibTeX |
| Original language: | English |
| Field: | General mathematics |
| Type: | Article in Proceedings |
| Keywords: | finite automata; two -way deterministic automata; periodicity; transformation semigroups; unary languages |
A framework for the study of periodic behaviour of two-way deterministic finite automata (2DFA) is developed. Computations of 2DFAs are represented by a two-way analogue of transformation semigroups, every element of which describes the behaviour of a 2DFA on a certain string x. A subsemigroup generated by this element represents the behaviour on strings in x^+. The main contribution of this paper is a description of all such monogenic subsemigroups up to isomorphism. This characterization is then used to show that transforming an n-state 2DFA over a one-letter alphabet to an equivalent sweeping 2DFA requires exactly n + 1 states, and transforming it to a one-way automaton requires exactly max{G(n-l) + l + 1 | 0 <= l <= n} states, where G(k) is the maximum order of a permutation of k elements.
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