Groups with Decomposable Set of Quasinormal Subgroups

A subgroup H of a group G is said to be quasinormal if HX = XH for all subgroups X of G. In this article groups are characterized for which the partially ordered set of quasinormal subgroups is decomposable.

The Deformed Trigonometric Functions of two Variables

MSC 2010: 33B10, 33E20