Totally conjugate orthogonal quasigroups and complete graphs

In this article, we study the spectrum of quasigroups all conjugates of which are distinct and pairwise orthogonal. We call such quasigroups totally conjugate orthogonal quasigroups (for brevity, totCO-quasigroups). Every totCO-quasigroup defines the complete conjugate orthogonal Latin square graph K ₆. Examples of totCO-quasigroups of different orders are given.     

On order polynomially complete lattices

One of the problems in the theory of order polynomially complete lattices is the question whether an order polynomially complete lattice is necessarily finite. In this note we give a partial answer to this problem by showing: No unbounded lattice is order polynomially complete. From this we deduce that a polynomially complete lattice cannot be countably infinite.Presented by I. Rosenberg.     

Algebraic properties of quantum quasigroups

Quantum quasigroups provide a self-dual framework for the unification of quasigroups and Hopf algebras. This paper furthers the transfer program, investigating extensions to quantum quasigroups of various algebraic features of quasigroups and Hopf algebras. Part of the difficulty of the transfer program is the fact that there is no standard model-theoretic procedure for accommodating the coalgebraic aspects of quantum quasigroups. The linear quantum quasigroups, which live in categories of modules under the direct sum, are a notable exception. They form one of the central themes of the paper.From the theory of Hopf algebras, we transfer the study of grouplike and setlike elements, which form separate concepts in quantum quasigroups. From quasigroups, we transfer the study of conjugate quasigroups, which reflect the triality symmetry of the language of quasigroups. In particular, we construct conjugates of cocommutative Hopf algebras. Semisymmetry, Mendelsohn, and distributivity properties are formulated for quantum quasigroups. We classify distributive linear quantum quasigroups that furnish solutions to the quantum Yang-Baxter equation. The transfer of semisymmetry is designed to prepare for a quantization of web geometry.     

On linear representations of quasigroups

For homotopies of quasigroups, an analog of the fundamental theorem on homomorphisms does not hold in general. In this paper, we consider two approaches that allow one to obtain an analog of this theorem: the introduction of strict homotopies and the move from quasigroups to three-sorted quasigroups.     

Polynomials on locally k-convex spaces

Polynomially bornological, polynomially barrelled and polynomially infrabarrelled locally convex spaces over a non-Archimedean non-trivially valued complete field of characteristic zero are introduced and studied.     

Shop scheduling problems with multiprocessor tasks on dedicated processors

The computational complexity of shop scheduling problems with multiprocessor tasks on dedicated processors is investigated. The objective is makespan minimization. Preemption of tasks is not allowed. For open and flow-shop problems with three stages, complete classifications into polynomial solvable and NP-hard problems are given. These classifications depend on the compatibility structures of the problems. Furthermore, results for open-shop problems with unit processing times are derived. Finally, it is shown that most of the special cases of the job-shop problem which are polynomially solvable remain polynomially solvable in the multiprocessor task situation.Supported by the Deutsche Forschungsgemeinschaft, Project JoPTAG.     

On quasigroups with few associative triples

There are numerous application of quasigroups in cryptology. It turns out that quasigroups with the relatively small number of associative triples can be utilized in designs of hash functions. In this paper we provide both a new lower bound and a new upper bound on the minimum number of associative triples over quasigroups of a given order.     

A generalization of the singular direct product with applications to skew Room squares

The singular direct product employed in the construction of certain designs and quasigroups, is generalized. When applied to skew Room squares, it extends earlier results to show that the spectrum is complete for values above 237.     

Varieties of quasigroups arising from 2-perfect m-cycle systems

For m = 6 and for all odd composite integers m, as well as for all even integers m 10 that satisfy certain conditions, 2-perfect m-cycle systems are constructed whose quasigroups have a homomorphism onto quasigroups which do not correspond to a 2-perfect m-cycle systems. Thus it is shown that for these values of m the class of quasigroups arising from all 2-perfect m-cycle systems does not form a variety.     

A graph-theoretic approach to quasigroup cycle numbers

Norton and Stein associated a number with each idempotent quasigroup or diagonalized Latin square of given finite order n, showing that it is congruent mod 2 to the triangular number T(n). In this paper, we use a graph-theoretic approach to extend their invariant to an arbitrary finite quasigroup. We call it the cycle number, and identify it as the number of connected components in a certain graph, the cycle graph. The congruence obtained by Norton and Stein extends to the general case, giving a simplified proof (with topology replacing case analysis) of the well-known congruence restriction on the possible orders of general Schroeder quasigroups. Cycle numbers correlate nicely with algebraic properties of quasigroups. Certain well-known classes of quasigroups, such as Schroeder quasigroups and commutative Moufang loops, are shown to maximize the cycle number among all quasigroups belonging to a more general class.     

带可分解性质的幂等拟群大集

具有幂单正交侣的幂等拟群称为可分解的. 具有幂等正交侣的幂等拟群称为几乎可分解的. 若v 元集合上的所有分量互不相同的3-向量能够分拆成互不相交(幂等3-向量除外) 的v-2 个v 阶幂等拟群, 则称之为v 阶幂等拟群大集. 本文使用t-平衡设计(t=2; 3) 的方法给出了可分解幂等拟群大集、几乎可分解幂等拟群大集及可分解对称幂等拟群大集(即可分解高尔夫设计) 的构造方法, 给出了其存在性的若干结果.     

Napoleon’s quasigroups

Napoleon’s quasigroups are idempotent medial quasigroups satisfying the identity (ab·b)(b·ba) = b. In works by V. Volenec geometric terminology has been introduced in medial quasigroups, enabling proofs of many theorems of plane geometry to be carried out by formal calculations in a quasigroup. This class of quasigroups is particularly suited for proving Napoleon’s theorem and other similar theorems about equilateral triangles and centroids.     

Homotopies of Central Quasigroups

The article analyzes homotopies between central quasigroups, and their groups of autotopies. In particular, the cycle types of autotopies of central quasigroups and other group isotopes of prime order are identified.     

Generalized linear functional equations on almost quasigroups I: Equations with at most two variables

Summary. We define almost quasigroups, a new class of groupoids which generalize quasigroups, and prove several representation theorems for them, essentially reducing them to loops (see Theorems 1, 2 and 9). Some well-known theorems on quasigroups are generalized, notably the theorems of A. A. Albert (Theorems 8, 9 and 10).¶We also define the normal form of equations and show that every generalized linear functional equation Eq on almost quasigroups is equivalent to a system consisting of several equations with at most one variable each, and one equation in the normal form, with the same number of variables as Eq. Eventually, the general solution of the generalized linear functional equations on almost quasigroups with at most two variables is given.¶We plan to solve other generalized linear functional equations in subsequent papers.     

带共轭性质拟群的计数

由-个拟群(Q,(×))可以定义出6个共轭拟群,这6个共轭拟群不一定互不相同,其构成的集合C(Q,(×))的基数t可能的取值是1,2,3或6.记q(n,t)是所有满足|C(Q,(×))|=t的n阶拟群的个数,本文将给出q(n,2)和q(n,6)的计数问题.     

Constructing identities for finite quasigroups

An algorithm for producing identities which hold in any given finite quasigroup is described. Identities produced by the algorithm are used to prove several results concerning varieties of quasigroups. In particular varieties of quasigroups associated with various combinatorial designs are examined.     

An o-minimal structure without mild parameterization

We prove, by explicit construction, that not all sets definable in polynomially bounded o-minimal structures have mild parameterization. Our methods do not depend on the bounds particular to the definition of mildness and therefore our construction is also valid for a generalized form of parameterization, which we call G-mild. Moreover, we present a cell decomposition result for certain o-minimal structures which may be of independent interest. This allows us to show how our construction can produce polynomially bounded, model complete expansions of the real ordered field which, in addition to lacking G-mild parameterization, nonetheless still have analytic cell decomposition.     

Quasigroups and tactical systems

A quasigroupQ is a set together with a binary operation which satisfies the condition that any two elements of the equationxy =z uniquely determines the third. A quasigroup is in indempotent when any elementx satisfies the indentityxx =x. Several types of Tactical Systems are defined as arrangement of points into “blocks” in such a way as to balance the incidence of (ordered or unordered) pairs of points, and shown to be coexistent with idempotent quasigroups satisfying certain identifies. In particular the correspondences given are: 1. totally symmetric idempotent quasigroups and Steiner triple systems, 2. semi-symmetric idempotent quasigroups and directed triple systems, 3. idempotent quasigroups satisfying Schröder's Second Law, namely (xy)(yx)=x, and triple tourna-ments, and 4. idempotent quasigroups satisfying Stein's Third Law, namely (xy)(yx)=y, and directed tournaments. These correspondences are used to obtain corollaries on the existence of such quasig-roups from constructions of the Tactical Systems. In particular this provides a counterexample to an ”almost conjecture“ of Norton and Stein (1956) concerning the existence of those quasigroups in 3 and 4 above. Indeed no idempotent qnasigroups satisfying Stein's Third Law and with order divisible by four were known to N. S. Mendelsohn when he wrote a paper on such quasigroups for the Third Waterloo Conference on Combinatorics (May, 1968). Finally, a construction for triple tournaments is interpreted as a Generalized Semi-Direct Product of idempotent quasigroups.     

Homotopy and semisymmetry of quasigroups

The study of quasigroup homotopies reduces to the study of homomorphisms between semisymmetric quasigroups. In particular, the study of homotopies between central quasigroups reduces to the study of homomorphisms between entropic semisymmetric quasigroups. Received December 20, 1996; accepted in final form September 17, 1997.     

On congruences and ideals of partially ordered quasigroups

Some results concerning congruence relations on partially ordered quasigroups (especially, Riesz quasigroups) and ideals of partially ordered loops are presented. These results generalize the assertions which were proved by Fuchs in [5] for partially ordered groups and Riesz groups.