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Right division in Moufang loops

Maria de Lourdes M. Giuliani, Kenneth Walter Johnson (2010)

Commentationes Mathematicae Universitatis Carolinae

If ( G , · ) is a group, and the operation ( * ) is defined by x * y = x · y - 1 then by direct verification ( G , * ) is a quasigroup which satisfies the identity ( x * y ) * ( z * y ) = x * z . Conversely, if one starts with a quasigroup satisfying the latter identity the group ( G , · ) can be constructed, so that in effect ( G , · ) is determined by its right division operation. Here the analogous situation is examined for a Moufang loop. Subtleties arise which are not present in the group case since there is a choice of defining identities and the identities produced by...

Rough semigroups and rough fuzzy semigroups based on fuzzy ideals

Qiumei Wang, Jianming Zhan (2016)

Open Mathematics

In this paper, we firstly introduce a special congruence relation U(μ, t) induced by a fuzzy ideal μ in a semigroup S. Then we define the lower and upper approximations based on a fuzzy ideal in semigroups. We can establish rough semigroups, rough ideals, rough prime ideals, rough fuzzy semigroups, rough fuzzy ideals and rough fuzzy prime ideals according to the definitions of rough sets and rough fuzzy sets. Furthermore, we shall consider the relationships among semigroups and rough semigroups,...

Schreier loops

Péter T. Nagy, Karl Strambach (2008)

Czechoslovak Mathematical Journal

We study systematically the natural generalization of Schreier's extension theory to obtain proper loops and show that this construction gives a rich family of examples of loops in all traditional common, important loop classes.

Selfdistributive groupoids of small orders

Jaroslav Ježek, Tomáš Kepka (1997)

Czechoslovak Mathematical Journal

After enumerating isomorphism types of at most five-element left distributive groupoids, we prove that a distributive groupoid with less than 81 elements is necessarily medial.

Semisymmetrization and Mendelsohn quasigroups

Jonathan D. H. Smith (2020)

Commentationes Mathematicae Universitatis Carolinae

The semisymmetrization of an arbitrary quasigroup builds a semisymmetric quasigroup structure on the cube of the underlying set of the quasigroup. It serves to reduce homotopies to homomorphisms. An alternative semisymmetrization on the square of the underlying set was recently introduced by A. Krapež and Z. Petrić. Their construction in fact yields a Mendelsohn quasigroup, which is idempotent as well as semisymmetric. We describe it as the Mendelsohnization of the original quasigroup. For quasigroups...

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