Relative Kazhdan property
Remarks on Characters of Discrete Nilpotent Groups.
Representations and Positive Definite Functions on Hypergroups
Some relationships between representations of a hypergroup X, its algebras, and positive definite functions on X are studied. Also, various types of convergence of positive definite functions on X are discussed.
Representations of involutive semigroups.
Resonance classes of measures.