It is well known that the pushdown store language P(M) of a pushdown automaton (PDA) M - i.e., the language consisting of words occurring on the pushdown along accepting computations of M - is a regular language. Here, we design succinct nondeterministic finite automata (NFA) accepting P(M). In detail, an upper bound on the size of an NFA for P(M) is obtained, which is quadratic in the number of states and linear in the number of pushdown symbols of M. Moreover, this upper bound is shown to be asymptotically optimal. Then, several restricted variants of PDA are considered, leading to improved constructions. In all cases, we prove the asymptotical optimality of the size of the resulting NFA. Finally, we apply our results to decidability questions related to PDA, and obtain solutions in deterministic polynomial time.
|Titolo:||Descriptional complexity of pushdown store languages|
PALANO, BEATRICE SANTA (Ultimo)
|Parole Chiave:||decidability questions; descriptional complexity; pushdown automata; pushdown store languages|
|Settore Scientifico Disciplinare:||Settore INF/01 - Informatica|
|Data di pubblicazione:||2012|
|Appare nelle tipologie:||01 - Articolo su periodico|