8 research outputs found
Commutativity pattern of finite non-abelian -groups determine their orders
Let be a non-abelian group and be the center of . Associate a
graph (called non-commuting graph of ) with as follows: take
as the vertices of and join two distinct vertices
and , whenever . Here, we prove that "the commutativity
pattern of a finite non-abelian -group determine its order among the class
of groups"; this means that if is a finite non-abelian -group such that
for some group , then .Comment: to appear in Communications in Algebr
A note on the coprime graph of a group
In this paper we study the coprime graph of a group . The coprime graph of a group , is a graph whose vertices are elements of and two distinct vertices and are adjacent iff . In this paper we classify all the groups which the coprime graph is a complete r-partite graph or a planar graph. Also we study the automorphism group of the coprime graph
Some results on the comaximal ideal graph of a commutative ring
Let R R be a commutative ring with unity. The comaximal ideal graph of R R, denoted by C(R) C(R), is a graph whose vertices are the proper ideals of R R which are not contained in the Jacobson radical of R R, and two vertices I 1 I1 and I 2 I2 are adjacent if and only if I 1 +I 2 =R I1+I2=R. In this paper, we classify all comaximal ideal graphs with finite independence number and present a formula to calculate this number. Also, the domination number of C(R) C(R) for a ring R R is determined. In the last section, we introduce all planar and toroidal comaximal ideal graphs. Moreover, the commutative rings with isomorphic comaximal ideal graphs are characterized. In particular we show that every finite comaximal ideal graph is isomorphic to some C(Z n ) C(Zn)