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On directable nondeterministic trapped automata1
B. Imreh 2, Cs. Imreh 2, and M. Ito 3
Acta Cybernetica 16 (2003) 37-45.
Abstract:
A finite automaton is said to be directable if it has an
input word, a directing word, which takes it from every state
into the same state. For nondeterministic (n.d.) automata,
directability can be generalized in several ways. In
[#!imstnd!#], three such notions, D1-, D2-, and
D3-directability, are introduced. In this paper, we introduce
the trapped n.d. automata, and for each 
present lower and upper bounds for the lengths
of the shortest D
-directing words of 
-state
D
-directable trapped n.d. automata. It
turns out that for this special class of n.d. automata,
better bounds can be found than for the general case,
and some of the obtained bounds are sharp.
Footnotes
This work has been supported by a collaboration between the Hungarian Academy of Science and the Japan Society for the Promotion of Science, and the Hungarian National Foundation for Science Research, Grant T037258.
Institute of Informatics, University of Szeged, Árpád tér 2, H-6720 Szeged, Hungary
Dept. of Mathematics, Faculty of Science, Kyoto Sangyo University, Kyoto 603, Japan
Web administrator 2003-10-13