منابع مشابه
Tameness of The Pseudovariety Ls1
A class of finite semigroups V is said to be decidable if the membership problem for V has a solution, that is, if we can construct an algorithm to test whether a given semigroup lies in V. Decidability of pseudovarieties is not preserved by some of the most common pseudovariety operators, such as semidirect product, Mal’cev product and join [1, 17]. In particular Rhodes [17] has exhibited a de...
متن کاملTameness of pseudovariety joins
The concept of tameness of a pseudovariety was introduced by Almeida and Steinberg [1] as a tool for proving decidability of the membership problem for semidirect products of pseudovarieties. Recall that the join V ∨ W of two pseudovarieties V and W is the least pseudovariety containing both V and W. This talk is concerned with the problem of proving tameness of joins. This problem was consider...
متن کاملTameness of pseudovariety joins involving R 1
In this paper, we establish several decidability results for pseudovariety joins of the form V ∨ W, where V is a subpseudovariety of J or the pseudovariety R. Here, J (resp. R) denotes the pseudovariety of all J-trivial (resp. R-trivial) semigroups. In particular, we show that the pseudovariety V ∨ W is (completely) κ-tame when V is a subpseudovariety of J with decidable κ-word problem and W is...
متن کاملTameness of Joins involving the Pseudovariety of Local Semilattices
In this paper we prove that, if V is a κ-tame pseudovariety which satisfies the pseudoidentity xyz = xyz, then the pseudovariety join LSl∨V is also κ-tame. Here, LSl denotes the pseudovariety of local semilattices and κ denotes the implicit signature consisting of the multiplication and the (ω − 1)-power. As a consequence, we deduce that LSl ∨V is decidable. In particular the joins LSl ∨ Ab, LS...
متن کاملSemidirect Product with an Order-computable Pseudovariety and Tameness
The semidirect product of pseudovarieties of semigroups with an order-computable pseudovariety is investigated. The essential tool is the natural representation of the corresponding relatively free profinite semigroups and how it transforms implicit signatures. Several results concerning the behavior of the operation with respect to various kinds of tameness properties are obtained as applicati...
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ژورنال
عنوان ژورنال: International Journal of Algebra and Computation
سال: 2004
ISSN: 0218-1967,1793-6500
DOI: 10.1142/s0218196704001955