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In this paper we introduce the graph Γ s c (G) associated with a group G , called the solvable conjugacy class graph (abbreviated as SCC-graph), whose vertices are the nontrivial conjugacy classes of G and two distinct conjugacy classes C , D are adjacent if there exist x ∈ C and y ∈ D such that 〈 x , y 〉 is solvable. We discuss the connectivity, girth, clique number, and several other properties of the SCC-graph. One of our results asserts that there are only finitely many finite groups whose SCC-graph has given clique number d , and we find explicitly the list of such groups with d = 2. We pose some problems on the relation of the SCC-graph to the solvable graph and to the NCC-graph, which we cannot solve. [ABSTRACT FROM AUTHOR]

Abstract: Huber (1956)  considered the following problem on the hyperbolic plane . Consider a strictly hyperbolic subgroup of automorphisms on with compact quotient, and choose a conjugacy class in this group. Count the number of vertices inside an increasing ball, which are images of a fixed point under automorphisms in the chosen conjugacy class, and describe the asymptotic behaviour of this number as the size of the ball goes to infinity. We use a well-known analogy between the hyperbolic plane and the regular tree to solve this problem on the regular tree. [Copyright &y& Elsevier]