A Contraction Method to Decide Monadic Second-order Theories of Trees

Relatore
Gabriele Puppis - Dipartimento di Matematica e Informatica, Udine

Data e ora
martedì 20 novembre 2007 alle ore 17.00 - Inizio alle 17:30, Caffe' e biscotti alle 17:00.

Luogo
Ca' Vignal 3 - Piramide, Piano 0, Sala Verde

Referente
Tiziano Villa

Referente esterno

Data pubblicazione
6 novembre 2007

Dipartimento
 

Riassunto

We generalize the contraction method, originally proposed by Elgot
and Rabin and later extended by Carton and Thomas, from labeled
linear orderings to deterministic colored trees. We introduce a suitable
notion of indistinguishability of trees with respect to tree automata
and we take advantage of compositional properties of trees to reduce a
number of instances of the acceptance problem for tree auotomata to
simple instances involving regular trees. We prove that such a method
works effectively for a large class of trees, which is closed under
noticeable operations and includes all deterministic trees in the
Caucal hierarchy as well as several trees outside it.
ornamento
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