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A short direct characterization of GS-quasigroups

Zdenka Kolar-Begović (2011)

Czechoslovak Mathematical Journal

The theorem about the characterization of a GS-quasigroup by means of a commutative group in which there is an automorphism which satisfies certain conditions, is proved directly.

A tree as a finite nonempty set with a binary operation

Ladislav Nebeský (2000)

Mathematica Bohemica

A (finite) acyclic connected graph is called a tree. Let W be a finite nonempty set, and let H ( W ) be the set of all trees T with the property that W is the vertex set of T . We will find a one-to-one correspondence between H ( W ) and the set of all binary operations on W which satisfy a certain set of three axioms (stated in this note).

Affine regular decagons in GS-quasigroup

Vladimír Volenec, Zdenka Kolar-Begović (2008)

Commentationes Mathematicae Universitatis Carolinae

In this article the “geometric” concept of the affine regular decagon in a general GS–quasigroup is introduced. The relationships between affine regular decagon and some other geometric concepts in a general GS–quasigroup are explored. The geometrical presentation of all proved statements is given in the GS–quasigroup ( 1 2 ( 1 + 5 ) ) .

Affine regular icosahedron circumscribed around the affine regular octahedron in GS--quasigroup

Vladimír Volenec, Z. Kolar--Begović, R. Kolar--Šuper (2012)

Commentationes Mathematicae Universitatis Carolinae

The concept of the affine regular icosahedron and affine regular octahedron in a general GS-quasigroup will be introduced in this paper. The theorem of the unique determination of the affine regular icosahedron by means of its four vertices which satisfy certain conditions will be proved. The connection between affine regular icosahedron and affine regular octahedron in a general GS-quasigroup will be researched. The geometrical representation of the introduced concepts and relations between them...

Algebraic aspects of web geometry

Maks A. Akivis, Vladislav V. Goldberg (2000)

Commentationes Mathematicae Universitatis Carolinae

Algebraic aspects of web geometry, namely its connections with the quasigroup and loop theory, the theory of local differential quasigroups and loops, and the theory of local algebras are discussed.

Algorithm for the complement of orthogonal operations

Iryna V. Fryz (2018)

Commentationes Mathematicae Universitatis Carolinae

G. B. Belyavskaya and G. L. Mullen showed the existence of a complement for a k -tuple of orthogonal n -ary operations, where k < n , to an n -tuple of orthogonal n -ary operations. But they proposed no method for complementing. In this article, we give an algorithm for complementing a k -tuple of orthogonal n -ary operations to an n -tuple of orthogonal n -ary operations and an algorithm for complementing a k -tuple of orthogonal k -ary operations to an n -tuple of orthogonal n -ary operations. Also we find some...

Almost associative operations generating a minimal clone

Tamás Waldhauser (2006)

Discussiones Mathematicae - General Algebra and Applications

Characterizations of 'almost associative' binary operations generating a minimal clone are given for two interpretations of the term 'almost associative'. One of them uses the associative spectrum, the other one uses the index of nonassociativity to measure how far an operation is from being associative.

A-loops close to code loops are groups

Aleš Drápal (2000)

Commentationes Mathematicae Universitatis Carolinae

Let Q be a diassociative A-loop which is centrally nilpotent of class 2 and which is not a group. Then the factor over the centre cannot be an elementary abelian 2-group.

An algebraic characterization of geodetic graphs

Ladislav Nebeský (1998)

Czechoslovak Mathematical Journal

We say that a binary operation * is associated with a (finite undirected) graph G (without loops and multiple edges) if * is defined on V ( G ) and u v E ( G ) if and only if u v , u * v = v and v * u = u for any u , v V ( G ) . In the paper it is proved that a connected graph G is geodetic if and only if there exists a binary operation associated with G which fulfils a certain set of four axioms. (This characterization is obtained as an immediate consequence of a stronger result proved in the paper).

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