Forest algebras
نویسندگان
چکیده
If in a transformation semigroup we assume that the set being acted upon has a semigroup structure, then the transformation semigroup can be used to recognize languages of unranked trees. This observation allows us to examine the relationship connecting languages of unranked trees with standard algebraic concepts such as aperiodicity, idempotency, commutativity and wreath product. In particular, we give algebraic characterizations of first-order logic, chain logic, CTL* and PDL. These do not, however, yield decidability results.
منابع مشابه
Forest Algebras, ω-Algebras and A Canonical Form for Certain Relatively Free ω-Algebras
Forest algebras are defined for investigating languages of forests [ordered sequences] of unranked trees, where a node may have more than two [ordered] successors [9]. We show that several parameters on forests can be realized as forest algebra homomorphisms from the free forest algebra into algebras which retain the equational axioms of forest algebras. This includes the number of nodes, the n...
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