Caspian Journal of Mathematical Sciences
Volume:10 Issue: 1, Winter Spring 2021

‎In this paper‎, ‎we first give an overview of doubly stochastic interval matrices‎. ‎Then‎, ‎we present some theories about the interval linear system whose coefficient matrix is doubly stochastic interval matrix‎. ‎Also‎, ‎we give an outer estimation for the solution set of these systems‎.

Let $L$ be a lattice with the greatest element 1. Following the concept of strongly hollow elements of commutative rings, we define strongly hollow elements of lattices and we will make an intensive investigate the basic properties and possible structures of these elements.

We consider superquadratic functions f and define selfadjoint operators f(A) from some selfadjoint operators A on a reproducing kernel Hilbert space H=H(Q). We estimate the so-called Berezin number of operator f(A).

Using the method of sub-super solutions, we study the existence of positive solutions for a class of singular nonlinear semipositone systems involving nonlocal operator.

In this paper, we investigate two new subclasses $S^*_sigma(a, b)$ and $nu_sigma(a, b)$ of $sigma$ consisting of analytic and bi-univalent functions satisfying subordinations in the open unit disk $mathbb{U}$. We consider the Fekete-Szeg"{o} inequalities for these new subclasses. Also, we establish estimates for the coefficient for these subclasses.

In this paper, we introduce the concept of weakly $b-(varphi,G)$ contraction mapping in $b$-metric spaces endowed with a graph and give some fixed point results for such contractions.

The object of this paper is to study of D-concircular curvature tensor on generalized Sasakian-space-forms. Actually we consider generalized Sasakian-space-forms when it is, respectively: D-concircularly flat; D-concircular-pseudosymmetric; D-concircularly Ricci-semisymmetric; D-concircularly symmetric; $V (xi;X) .R = 0$. Most of the main results obtained in this paper are in the form of necessary and sufficient conditions.

This study is concerned with exploiting the spectral method to solve the fourth-order boundary value problem (BVP). Such equations frequently arise in the study and modeling of large amplitude transverse buckling in an elastic beam. To this end, the properties of shifted Legendre polynomial together with its operational matrix of the derivative and the spectral method is utilized to reduce BVP to a system of algebraic equations. Numerical results turn out the efficiency and accuracy of the propounded technique.

In this paper we introduce the concept of ideal and bi-ideal elements in poe-AG-groupoid and give some characterizations and properties of their bi-ideal elements. So we consider some results concerning bi-ideals in poe-semigroups and investigate them in poe-AG-groupoids. Also, the class of bi-ideal elements of poe-AG-groupoids are studied, certain intrinsic and basic properties of poe-AG-groupoids including:∧-semilattice, bi-ideal, semiprime, weaklyprime, totallyorderedelements and etc. are studied as well. The corresponding results on poe-semigroups can be also obtained as application of the results of this paper.

‎ ‎Let $(tilde{X},p)$ be the universal covering space of a compact metrizable space $ X $‎, ‎which is compact and locally path connected‎. ‎In this paper‎, ‎we show that there exist metrics $ d $ and $ d' $ for $ X $ and $tilde{X} $‎, ‎respectively‎, ‎such that any contractive map ‎$ f:Xto X $ induces a contractive map on $ tilde{X}$. ‎As an‎ application‎, ‎it is obtained that every iterated function system(IFS) on the space $ X $ with attractor $ K $‎, ‎induces an IFS on $tilde{ X} $ with attractor $tilde{K},$ such that $ p(tilde{K})=K$‎.