It is proved that finite nonabelian simple groups S with max π(S) = 37 are uniquely determined by their order and degree pattern in the class of all finite groups.
IntroductionThroughout this note, all the groups under consideration are finite, and simple groups are nonabelian. Given a group G, the spectrum ω(G) of G is the set of orders of elements in G. Clearly, the spectrum ω(G) is closed and partially ordered by the divisibility relation, and hence is uniquely determined by the set µ(G) of its elements which are maximal under the divisibility relation.One of the most well-known graphs associated with G is the prime graph (or Gruenberg-Kegel graph) denoted by GK(G). The vertices of GK(G) are the prime divisors of |G| and two distinct vertices p and q are joined by an edge (written by p, where d G (p i ) denotes the degree of p i in the prime graph GK(G). We call this k-tuple D(G) the degree pattern of G. In addition, we denote by OD(G) the set of pairwise non-isomorphic finite groups with the same order and degree pattern as G, and put h(G) = |OD(G)|. Since there are only finitely many isomorphism types of groups of order |G|, 1 h(G) < ∞. Now, we have the following definition.Usually, a 1-fold ODcharacterizable group is simply called OD-characterizable, and it is called quasi OD-characterizable if it is k-fold OD-characterizable for some k > 1.