منابع مشابه
Join irreducible semigroups
We begin a systematic study of those finite semigroups that generate join irreducible members of the lattice of pseudovarieties of finite semigroups, which are important for the spectral theory of this lattice. Finite semigroups S that generate join irreducible pseudovari-eties are characterized as follows: whenever S divides a direct product A × B of finite semigroups, then S divides either A ...
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We call a pseudovariety finite join irreducible if V ≤ V1 ∨V2 =⇒ V ≤ V1 or V ≤ V2. We present a large class of group mapping semigroups generating finite join irreducible pseudovarieties. We show that many naturally occurring pseudovarieties are finite join irreducible including: S, DS, CR, CS and H, where H is a group pseudovariety containing a non-nilpotent group.
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This paper is a contribution to the study of a quasi-order on the set Ω of Boolean functions, the simple minor quasi-order. We look at the join-irreducible members of the resulting poset Ω̃. Using a two-way correspondence between Boolean functions and hypergraphs, join-irreducibility translates into a combinatorial property of hypergraphs. We observe that among Steiner systems, those which yield...
متن کاملIrreducible Numerical Semigroups
We give a characterization for irreducible numerical semi-groups. From this characterization we obtain that every irre-ducible numerical semigroup is either a symmetric or pseudo-symmetric numerical semigroup. We study the minimal presentations of an irreducible numerical semigroup. Separately, we deal with the cases of maximal embedding dimension and multiplicity 3 and 4.
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In this paper, we characterize and find the number of subdirectly irreducible acts over some classes of semigroups, such as zero semigroups, right zero semigroups and strong chain of left zero semigroups.
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ژورنال
عنوان ژورنال: International Journal of Algebra and Computation
سال: 2019
ISSN: 0218-1967,1793-6500
DOI: 10.1142/s0218196719500498