TY - JOUR
T1 - Super graphs on groups, I
AU - Arunkumar, G.
AU - Cameron, Peter J.
AU - Nath, Rajat Kanti
AU - Selvaganesh, Lavanya
PY - 2022/6
Y1 - 2022/6
N2 - Let G be a finite group. A number of graphs with the vertex set G have been studied, including the power graph, enhanced power graph, and commuting graph. These graphs form a hierarchy under the inclusion of edge sets, and it is useful to study them together. In addition, several authors have considered modifying the definition of these graphs by choosing a natural equivalence relation on the group such as equality, conjugacy, or equal orders, and joining two elements if there are elements in their equivalence class that are adjacent in the original graph. In this way, we enlarge the hierarchy into a second dimension. Using the three graph types and three equivalence relations mentioned gives nine graphs, of which in general only two coincide; we find conditions on the group for some other pairs to be equal. These often define interesting classes of groups, such as EPPO groups, 2-Engel groups, and Dedekind groups.We study some properties of graphs in this new hierarchy. In particular, wecharacterize the groups for which the graphs are complete, andin most cases, we characterize the dominant vertices (those joined to allothers). Also, we give some results about universality, perfectness, and cliquenumber.
AB - Let G be a finite group. A number of graphs with the vertex set G have been studied, including the power graph, enhanced power graph, and commuting graph. These graphs form a hierarchy under the inclusion of edge sets, and it is useful to study them together. In addition, several authors have considered modifying the definition of these graphs by choosing a natural equivalence relation on the group such as equality, conjugacy, or equal orders, and joining two elements if there are elements in their equivalence class that are adjacent in the original graph. In this way, we enlarge the hierarchy into a second dimension. Using the three graph types and three equivalence relations mentioned gives nine graphs, of which in general only two coincide; we find conditions on the group for some other pairs to be equal. These often define interesting classes of groups, such as EPPO groups, 2-Engel groups, and Dedekind groups.We study some properties of graphs in this new hierarchy. In particular, wecharacterize the groups for which the graphs are complete, andin most cases, we characterize the dominant vertices (those joined to allothers). Also, we give some results about universality, perfectness, and cliquenumber.
KW - Power graph
KW - Commuting graph
KW - Conjugacy
KW - 2-Engel groups
KW - EPPO groups
U2 - 10.1007/s00373-022-02496-w
DO - 10.1007/s00373-022-02496-w
M3 - Article
SN - 0911-0119
VL - 38
JO - Graphs and Combinatorics
JF - Graphs and Combinatorics
IS - 3
M1 - 100
ER -