A. Hosseini
Department of Mathematics, Kashmar Higher Education Institute, Kashmar, Iran
[ 1 ] - Characterization of $delta$-double derivations on rings and algebras
The main purpose of this article is to offer some characterizations of $delta$-double derivations on rings and algebras. To reach this goal, we prove the following theorem:Let $n > 1$ be an integer and let $mathcal{R}$ be an $n!$-torsion free ring with the identity element $1$. Suppose that there exist two additive mappings $d,delta:Rto R$ such that $$d(x^n) =Sigma^n_{j=1} x^{n-j}d(x)x^{j-1}+Si...
[ 2 ] - On the Structure of Metric-like Spaces
The main purpose of this paper is to introduce several concepts of the metric-like spaces. For instance, we define concepts such as equal-like points, cluster points and completely separate points. Furthermore, this paper is an attempt to present compatibility definitions for the distance between a point and a subset of a metric-like space and also for the distance between two subsets of a metr...
[ 3 ] - حل معادلات عملگری X-AXB=C و A X+X^{*} C=B در مدول های-C^* هیلبرت
معادلات $X-AXB=C$ و $A X+X^{*} C=B$ دارای کاربرد وسیعی در نظریه کنترل و سیستم های خطی می باشند. در این پژوهش به بررسی شرط لازم و کافی برای وجود جواب آنها با در نظرگرفتن شرایطی پرداخته شده است. برای پیدا کردن جواب دقیق معادله دوم از نمایش ماتریسی عملگرها استفاده شده است، که این امکان را فراهم آورده، که بتوان جواب معادله را بر حسب وارون مور-...
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