The prime graphs of some classes of finite groups

In this paper we study prime graphs of finite groups. The prime graph of a finite group G, also known as the Gruenberg-Kegel graph, is the graph with vertex set {primes dividing vertical bar G vertical bar} and an edge p-q if and only if there exists an element of order pq in G. In finite group theory, studying the prime graph of a group has been an important topic for the past almost half century. Only recently prime graphs of solvable groups have been characterized in graph theoretical terms only. In this paper, we continue this line of research and give complete characterizations of several classes of groups, including groups of square-free order, metanilpotent groups, groups of cube-free order, and, for any n epsilon N, solvable groups of n(th)-power-free order. We also explore the prime graphs of groups whose composition factors are cyclic or A(5) and draw connections to a conjecture of Maslova. We then propose an algorithm that recovers the prime graph from a dual prime graph. (C) 2021 Elsevier B.V. All rights reserved.