Free rectangular doppelsemigroups

2019 ◽  
Vol 19 (11) ◽  
pp. 2050205 ◽  
Author(s):  
Anatolii V. Zhuchok ◽  
Yuliia V. Zhuchok ◽  
Jörg Koppitz

A doppelsemigroup is a nonempty set equipped with two binary associative operations satisfying certain identities. In this paper, we consider the variety of rectangular doppelsemigroups which are analogs of rectangular semigroups. We construct the free rectangular doppelsemigroup and characterize the least rectangular congruence on the free doppelsemigroup. As a consequence, the free rectangular semigroup is presented. We also describe all (maximal) subdoppelsemigroups, all idempotents and all endomorphisms of the free rectangular doppelsemigroup, and give a criterion for an isomorphism of endomorphism semigroups of free rectangular doppelsemigroups. In addition, we show that the endomorphism semigroup of the free rectangular doppelsemigroup is not regular in general.

2017 ◽  
Vol 16 (02) ◽  
pp. 1750031
Author(s):  
Ilinka Dimitrova ◽  
Vítor H. Fernandes ◽  
Jörg Koppitz

In this note, we consider the semigroup [Formula: see text] of all order endomorphisms of an infinite chain [Formula: see text] and the subset [Formula: see text] of [Formula: see text] of all transformations [Formula: see text] such that [Formula: see text]. For an infinite countable chain [Formula: see text], we give a necessary and sufficient condition on [Formula: see text] for [Formula: see text] to hold. We also present a sufficient condition on [Formula: see text] for [Formula: see text] to hold, for an arbitrary infinite chain [Formula: see text].


1967 ◽  
Vol 170 (4) ◽  
pp. 334-338 ◽  
Author(s):  
George Gr�tzer

2007 ◽  
Vol 17 (05n06) ◽  
pp. 1085-1106 ◽  
Author(s):  
G. MASHEVITZKY ◽  
B. I. PLOTKIN

Let U be a universal algebra. An automorphism α of the endomorphism semigroup of U defined by α(φ) = sφs-1 for a bijection s : U → U is called a quasi-inner automorphism. We characterize bijections on U defining such automorphisms. For this purpose, we introduce the notion of a pre-automorphism of U. In the case when U is a free universal algebra, the pre-automorphisms are precisely the well-known weak automorphisms of U. We also provide different characterizations of quasi-inner automorphisms of endomorphism semigroups of free universal algebras and reveal their structure. We apply obtained results for describing the structure of groups of automorphisms of categories of free universal algebras, isomorphisms between semigroups of endomorphisms of free universal algebras, automorphism groups of endomorphism semigroups of free Lie algebras etc.


1970 ◽  
Vol 32 (1) ◽  
pp. 55-60
Author(s):  
Subrata Majumdar ◽  
Mohd. Altab Hossain

The endomorphism semigroup for a class of commutative semigroups, called special semigroups, will be studied their structures will be determined in some important cases. AMS Classification : 20 Keywords: Special semigroups, freeness, divisibility, direct sums, endomorphism, endomorphism semigroup. doi: 10.3329/jbas.v32i1.2442 Journal of Bangladesh Academy of Sciences, Vol. 32, No. 1, 55-60, 2008


1996 ◽  
Vol 53 (3) ◽  
pp. 401-411
Author(s):  
K.D. Magill

For any topological near-ring (which is not a ring) whose additive group is the additive group of real numbers, we investigate the near-ring of all continuous functions, under the pointwise operations, from a compact Hausdorff space into that near-ring. Specifically, we determine all the homomorphisms from one such near-ring of functions to another and we show that within a rather extensive class of spaces, the endomorphism semigroup of the near-ring of functions completely determines the topological structure of the space.


2011 ◽  
Vol 333 (1) ◽  
pp. 40-54 ◽  
Author(s):  
A. Belov-Kanel ◽  
R. Lipyanski

Sign in / Sign up

Export Citation Format

Share Document