Previous Up Next Article
Citations From References: 0 From Reviews: 0
MR2341385 (2008f:68067) 68Q45
Gl¨ockler, Jens (D-GSSN-II)
Forgetting automata and unary languages. (English summary)
Internat. J. Found. Comput. Sci.18 (2007),no. 4,813–827.
A “forgetting automaton” is a linear bounded automaton that can only use the operations MX (move), EX (erase, i.e., rewrite with a special blank symbol) and DX (delete, i.e., remove com-pletely); X ∈ {L, R} denotes the direction of the input head. The 26− 1 = 63 nonempty subsets of these operations give rise to as many deterministic and nondeterministic automaton models and their language families. These families are all strictly included in the deterministic context-sensitive languages.
In [P. Janˇcar, F. Mr´az and M. Pl´atek, in SOFSEM’92, 41–44, Masaryk Univ., Brno, 1992; per bibl.; in Mathematical foundations of computer science 1993 (Gda´nsk, 1993), 527–536, Lecture Notes in Comput. Sci., 711, Springer, Berlin, 1993;MR1265088 (94k:68146)] many relationships between these language families were established. The present paper deals with some remaining ones as well as the relationships with other families: regular, linear, and metalinear languages, and languages accepted by counter automata. The second part of the paper is devoted to the special case of unary languages, i.e., the case in which the input alphabet consists of a single symbol only. {Reviewer’s remark: This paper is a slightly extended version of the author’s earlier work [in
Implementation and application of automata, 186–197, Lecture Notes in Comput. Sci., 4094,
Springer, Berlin, 2006;MR2296457].}
Reviewed byPeter R. J. Asveld c
