منابع مشابه
Combinatorial aspects of an exact sequence that is related to a graph
The five problems of counting component colorings, vertex colorings, arc colorings, cocycles, and switching equivalence classes of a graph with respect to a finite field up to isomorphism are related by an exact sequence that stems from a coboundary operator. This cohomology is presented, and counting formulas are given for each of the five problems.
متن کاملA note on a graph related to the comaximal ideal graph of a commutative ring
The rings considered in this article are commutative with identity which admit at least two maximal ideals. This article is inspired by the work done on the comaximal ideal graph of a commutative ring. Let R be a ring. We associate an undirected graph to R denoted by mathcal{G}(R), whose vertex set is the set of all proper ideals I of R such that Inotsubseteq J(R), where J(R) is...
متن کاملOn a sequence related to the coprime integers
The asymptotic behaviour of the sequence with general term $P_n=(varphi(1)+varphi(2)+cdots+varphi(n))/(1+2+cdots+n)$, is studied which appears in the studying of coprime integers, and an explicit bound for the difference $P_n-6/pi^2$ is found.
متن کاملOn the planarity of a graph related to the join of subgroups of a finite group
Let $G$ be a finite group which is not a cyclic $p$-group, $p$ a prime number. We define an undirected simple graph $Delta(G)$ whose vertices are the proper subgroups of $G$, which are not contained in the Frattini subgroup of $G$ and two vertices $H$ and $K$ are joined by an edge if and only if $G=langle H , Krangle$. In this paper we classify finite groups with planar graph. ...
متن کاملExact annihilating-ideal graph of commutative rings
The rings considered in this article are commutative rings with identity $1neq 0$. The aim of this article is to define and study the exact annihilating-ideal graph of commutative rings. We discuss the interplay between the ring-theoretic properties of a ring and graph-theoretic properties of exact annihilating-ideal graph of the ring.
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ژورنال
عنوان ژورنال: European Journal of Combinatorics
سال: 1996
ISSN: 0195-6698
DOI: 10.1006/eujc.1996.0037