pairs of groups

‎‎The equivalence relation isoclinism partitions the class of all pairs of groups‎ ‎into families‎. ‎In this paper‎, ‎a complete classification of the set of all pairs $(G,G')$ is established‏‎,‎ whenever‎ $G$ is a $p$-group of order at most $p^5‎‏$‎ and ‎$p$ is a prime number greater than 3. Moreover‎, ‎the classification of pairs $(H,H')$ for extra special $p$-groups $H$ is also given.

A group G is called capable if it is isomorphic to the group of inner automorphisms of some group H. The notion of capable groups was extended to capable pairs by G. Ellis, in 1996. Recently, a classification of capable pairs of finite abelian groups was given by A. Pourmirzaei, A. Hokmabadi and S. Kayvanfar. In this paper, we give a different characterization of capable pairs of finite abelian groups in terms of a condition on the lattice of subgroups.