Salti, Mustafa
Published in
Czechoslovak Journal of Physics

Using the Moller, Einstein, Bergmann-Thomson and Landau-Lifshitz energy-momentum definitions both in general relativity and teleparallel gravity, we find the energy-momentum of the closed universe based on the generalized Bianchi-I type metric.

Pitts, J. B. Schieve, W. C.
Published in
Theoretical and Mathematical Physics

We derive Einstein’s equations from a linear theory in flat space-time using free-field gauge invariance and universal coupling. The gravitational potential can be either covariant or contravariant and of almost any density weight. We adapt these results to yield universally coupled massive variants of Einstein’s equations, yielding two one-paramet...

Larin, S. V.
Published in
Journal of Mathematical Sciences

In this article, it is proved that if a group G coincides with its commutator subgroup, is generated by a finite set of classes of conjugate elements, and contains a proper minimal normal subgroup A such that the factor group G/A coincides with the normal closure of one element, then G coincides with the normal closure of an element. From this a po...

Dzhumadil’daev, A. S.
Published in
Journal of Mathematical Sciences

An algebra with the identity t1(t2t3) = (t1t2+t2t1)t3 is called Zinbiel. For example, ℂ[x] under the multiplication \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$a\b...

Pokornyi, Y. V. Zvereva, M. B. Ishchenko, A. S. Ryabtseva, N. N.
Published in
Journal of Mathematical Sciences

This paper suggests a method of “measure transformation” for justifying and studying problems of variational nature and nonstandard type.

Izumiya, Shyuichi
Published in
Journal of Mathematical Sciences

We construct a basic framework for studying the extrinsic differential geometry on time-like hypersurfaces in the de Sitter space from the viewpoint of the theory of Legendrian singularities. As an application, we study the contact of time-like hypersurfaces with flat totally umbilic time-like hypersurfaces in the de Sitter space.

Puusemp, P.
Published in
Journal of Mathematical Sciences

It is proved that among the finite groups of order 24 only the binary tetrahedral group is not determined by its endomorphism semigroup in the class of all groups.

Kartashova, A. V.
Published in
Journal of Mathematical Sciences

In this paper, it is shown that the topology lattice of any finite algebra is isomorphic to the topology lattice of some finite algebra with four unary operations. Further, we present countably many unary algebras whose topology lattices are distributive and nonisomorphic to a topology lattice of any unar (a unar is an algebra with one unary operat...

Golubeva, V. A.
Published in
Journal of Mathematical Sciences

After a short introduction devoted to the origin of the problem considered from the physical problems of quantum field theory and statistical mechanics, the paper considers the mathematical aspects of the Knizhnik-Zamolodchikov equation theory associated with various root systems and the results connected with the inverse monodromy problem for them...

Belykh, V. N. Komrakov, N. L. Ukrainskii, B. S.
Published in
Journal of Mathematical Sciences

Two problems are solved: the obtaining of hyperbolicity conditions for families of individual multidimensional mappings and applying these hyperbolicity conditions to a system of coupled mappings and the subsequent proof of the preservation of the hyperbolicity property for the important class of coupled mappings considered. The study is performed ...