Let G = Γ(S) be a semigroup graph, i.e., a zero-divisor graph of a semigroup S with zero element 0. For any adjacent vertices x, y in G, denote C(x,y) = {z∈V(G) | N (z) = {x,y}}. Assume that in G there exi...Let G = Γ(S) be a semigroup graph, i.e., a zero-divisor graph of a semigroup S with zero element 0. For any adjacent vertices x, y in G, denote C(x,y) = {z∈V(G) | N (z) = {x,y}}. Assume that in G there exist two adjacent vertices x, y, a vertex s∈C(x,y) and a vertex z such that d (s,z) = 3. This paper studies algebraic properties of S with such graphs G = Γ(S), giving some sub-semigroups and ideals of S. It constructs some classes of such semigroup graphs and classifies all semigroup graphs with the property in two cases.展开更多
We investigate the interaction between a ring R and the Cayley graph Cay(L(R)) of the semigroup of left ideals of R,as well as subdigraphs of this graph. Graph theoretic properties of these graphs are investigated,suc...We investigate the interaction between a ring R and the Cayley graph Cay(L(R)) of the semigroup of left ideals of R,as well as subdigraphs of this graph. Graph theoretic properties of these graphs are investigated,such as transitive closure,girth,radius,diameter,and spanning subgraphs.Conditions on certain of these graphs are given which imply that R is regular,left duo,or that the idempotents of R are central. We characterize simple rings in terms of Cay(L(R)). We characterize strongly regular rings in terms of a subdigraph of Cay(L(R)).展开更多
文摘Let G = Γ(S) be a semigroup graph, i.e., a zero-divisor graph of a semigroup S with zero element 0. For any adjacent vertices x, y in G, denote C(x,y) = {z∈V(G) | N (z) = {x,y}}. Assume that in G there exist two adjacent vertices x, y, a vertex s∈C(x,y) and a vertex z such that d (s,z) = 3. This paper studies algebraic properties of S with such graphs G = Γ(S), giving some sub-semigroups and ideals of S. It constructs some classes of such semigroup graphs and classifies all semigroup graphs with the property in two cases.
文摘We investigate the interaction between a ring R and the Cayley graph Cay(L(R)) of the semigroup of left ideals of R,as well as subdigraphs of this graph. Graph theoretic properties of these graphs are investigated,such as transitive closure,girth,radius,diameter,and spanning subgraphs.Conditions on certain of these graphs are given which imply that R is regular,left duo,or that the idempotents of R are central. We characterize simple rings in terms of Cay(L(R)). We characterize strongly regular rings in terms of a subdigraph of Cay(L(R)).
