S.M. Jafarian Amiri
Department of Mathematics, Faculty of Sciences, University of Zanjan, P.O. Box 45371-38791, Zanjan, Iran.
[ 1 ] - Finite groups all of whose proper centralizers are cyclic
A finite group $G$ is called a $CC$-group ($Gin CC$) if the centralizer of each noncentral element of $G$ is cyclic. In this article we determine all finite $CC$-groups.
[ 2 ] - Finite groups have even more centralizers
For a finite group $G$, let $Cent(G)$ denote the set of centralizers of single elements of $G$. In this note we prove that if $|G|leq frac{3}{2}|Cent(G)|$ and $G$ is 2-nilpotent, then $Gcong S_3, D_{10}$ or $S_3times S_3$. This result gives a partial and positive answer to a conjecture raised by A. R. Ashrafi [On finite groups with a given number of centralizers, Algebra Collo...
[ 3 ] - An Alexandroff topology on graphs
Let G = (V,E) be a locally finite graph, i.e. a graph in which every vertex has finitely many adjacent vertices. In this paper, we associate a topology to G, called graphic topology of G and we show that it is an Alexandroff topology, i.e. a topology in which intersec- tion of every family of open sets is open. Then we investigate some properties of this topology. Our motivation is to give an e...
[ 4 ] - Maximum sum element orders of all proper subgroups of PGL(2, q)
In this paper we show that if q is a power of a prime p , then the projective special linear group PSL(2, q) and the stabilizer of a point of the projective line have maximum sum element orders among all proper subgroups of projective general linear group PGL(2, q) for q odd and even respectively
[ 5 ] - صد سال با مرکزساز عضوهای گروه
مطالعۀ تاریخ ریاضی علاوه بر ادای دین نسبت به پیشگامان و تلاشگران این حوزۀ علمی، نحوۀ تکامل موضوعات ریاضی را نیز آشکار می کند. به ویژه ریاضی خوانان جوان طی مطالعۀ تاریخ ریاضی با جریان فکری حاکم بر فرآیند کشف قضیه های ریاضی آشنا می شوند و خود می توانند مستقلا به بازآفرینی روند حل مسائل و یادگیری عمیق ریاضی بپردازند. در این مقاله، تاریخچه ای از تعریف و به کارگیریِ مرکزساز عضوهای گروه ها را در شناسا...
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