ABOUT THE SCHUR INDEX FOR AMBIVALENT GROUPS

An ambivalent group is a finite group all of whose irreducible characters are real valued. By Brauer-Speiser theorem, if G is an ambivalent group, then the absolute Schur index m(Q)()=m() 2. In this note we shall prove that this property is true also for the derived subgroups of ambivalent groups. Also we will prove that there is a relation between the number of conjugacy classes of 2-regular cyclic subgroups of an ambivalent group and the irreducible characters with absolute Schur index 1.