Results 171 to 179 of about 2,610 (179)
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EXTENSIONS OF REGULAR ORTHOGROUPS BY INVERSE SEMIGROUPS
International Journal of Algebra and Computation, 1995Let V be a variety of regular orthogroups, i.e. completely regular orthodox semigroups whose band of idempotents is regular. Let S be an orthodox semigroup which is a (normal) extension of an orthogroup K from V by an inverse semigroup G, that is, there is a congruence ρ on S such that the semigroup ker ρ of all idempotent related elements of S is ...
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Λ-Right congruences and a classification of orthogroups
Acta Mathematica Hungarica, 1984The author defines a \(\wedge\)-right congruence on a completely regular semigroup S as any left congruence \(\rho\) on S for which (i) \(a\rho\) \(\hat a\) and (ii) \(a\rho\) b implies \(\hat ac\rho\) \^bc for any a,b,c in S. (Here \(\hat a\) denotes the unit of \(H_ a)\). The dual notion defines \(\wedge\)-left congruences.
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Bi-ideals in regular semigroups and in orthogroups
Acta Mathematica Hungarica, 1986The author investigates regular semigroups by means of their bi-ideals. A bi-ideal of a semigroup S is a subsemigroup \(B\subseteq S\) with BSB\(\subseteq B\); the bi-ideals of S form a semigroup \({\mathfrak B}(S)\) under complex multiplication. The following two 'reduction theorems' are proven for \({\mathfrak B}(S):\) 1.
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Maximal Normal Orthogroups in Rings Containing No Infinite Semilattices
Communications in Algebra, 2006ABSTRACT Let R be a ring regarded as a multiplicative semigroup which contains no infinite subsemilattices. We investigate subsemigroups of R which are normal orthogroups, and present a construction from which all such maximal normal orthogroups can be obtained.
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2022
The last eukaryotic common ancestor (LECA) was a unicellular heterotrophic organism that preyed upon bacteria through a process called phagocytosis. LECA’s descendents have evolved into many eukaryotic supergroups, and over this time endosymbiotic integration of cyanobacteria and then eukaryotic algae into diverse hosts has led to the establishment of ...
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The last eukaryotic common ancestor (LECA) was a unicellular heterotrophic organism that preyed upon bacteria through a process called phagocytosis. LECA’s descendents have evolved into many eukaryotic supergroups, and over this time endosymbiotic integration of cyanobacteria and then eukaryotic algae into diverse hosts has led to the establishment of ...
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On the characterization of particular orthogroups by disjunctions of identities
2018In this thesis, we discuss the characterization of orthogroups by so-called disjunctions of identities. The orthogroups are a subclass of the class of completely regular semigroups, a generalization of the concept of a group. Thus there is for all elements of an orthogroup some kind of an inverse element such that both elements commute.
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