Results 91 to 100 of about 136 (128)

Some relations on completely regular semigroups

Semigroup Forum, 2009
Two relations \(Y\) and \(\xi\) on completely regular semigroups \(S\) are studied in connection with the least Clifford congruence \(\nu\) [described by \textit{P. R. Jones}, Semigroup Forum 27, 390-392 (1983; Zbl 0537.20036)]. For \(Y\), defined by: \(aYb\) iff \(V(a)=V(b)\) (where \(V(a)\) denotes the set of all generalized inverses of \(a\in S ...
Zhang, Jiangang, Shen, Ran
exaly   +3 more sources

Orders in completely regular semigroups

Mathematika, 2001
A classic theorem of semigroup theory is that a semigroup \(S\) has a group of quotients if and only if it is reversible and cancellative. From the perspective of the group, it contains \(S\) as an ``order''. Generalizing from both this situation and from ring theory, a semigroup \(S\) is an order in another semigroup \(Q\) if every element in \(Q ...
exaly   +3 more sources

New operators for varieties of completely regular semigroups

Semigroup Forum, 2015
In a series of articles, starting with [J. Aust. Math. Soc. 83, No. 1, 87-104 (2007; Zbl 1142.20035)], the author has investigated the decomposition of the lattice of varieties of completely regular semigroups induced by intersecting with the variety \(\mathbf B\) of bands.
Mariio Petrich, Petrich Mario
exaly   +3 more sources

Perfect Completely Regular Semigroups

Mathematische Nachrichten, 1985
A congruence \(\sigma\) on a semigroup \(S\) is called perfect if for all \(a,b\in S\) we have \((a\sigma)(b\sigma)=(ab)\sigma\) where \(a\sigma\) denotes the \(\sigma\)-class containing \(a\). If every congruence on \(S\) is perfect, \(S\) is called perfect. In this paper the author characterizes perfect completely regular semigroups.
openaire   +1 more source

Unification Types of Completely Regular Semigroups

Journal of Automated Reasoning, 2002
Unification theory is concerned with solving equations in relatively free algebraic structures and has become an important topic in theoretical computer science. The paper characterizes the varieties of completely regular semigroups which contain all semilattices and are of unitary, finitary and infinitary unification type, respectively.
openaire   +1 more source

Completely regular semigroups

1995
Abstract It is well known that a group (G, μ) can alternatively be regarded as having three operations, namely the binary operation μ : (a, b)  ⟼ab, the unary operation a ⟼a-1, and the 0-ary operation (the constant) 1.
openaire   +1 more source

The Lattice of Varieties of Completely Regular Semigroups

Results in Mathematics, 2005
The completely regular semigroups form a variety \(\mathcal{CR}\), when considered as unary semigroups. After a period in which various principal ideals of the lattice \({\mathcal L}(\mathcal{CR})\) were described, \textit{L. Polák} [Semigroup Forum 36, No. 3, 253-284 (1987); ibid. 37, No.
openaire   +2 more sources

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