The paper focuses on deterministic and unambiguous recognizable two-dimensional languages with particular attention to the case of a one-letter alphabet. The family DREC(1) of deterministic languages over a one-letter alphabet is characterized as both L(DOTA)(1), the class of languages accepted by deterministic on-line tessellation acceptors, and L(2AFA)(1), the class of languages recognized by 2-way alternating finite automata. We show that there are inherently ambiguous languages and unambiguously recognizable languages that cannot be deterministically recognized even in the case of one-letter alphabet. In particular we show that on-line tessellation acceptors are more powerful than their deterministic counterpart, even in the case of a one-letter alphabet. Finally we show that DREC(1) is complex enough not to be characterized in terms of classical operations.
|Titolo:||Deterministic and Unambiguous Two-dimensional Languages over One-letter Alphabet|
|Data di pubblicazione:||2009|
|Citazione:||Deterministic and Unambiguous Two-dimensional Languages over One-letter Alphabet / ANSELMO M; MADONIA M. - In: THEORETICAL COMPUTER SCIENCE. - ISSN 0304-3975. - 410, n.16(2009), pp. 1477-1485.|
|Appare nelle tipologie:||1.1 Articolo in rivista|