NON-ISOMORPHIC GROUPS WITH ISOMORPHICSPECTRAL TABLES AND BURNSIDE MATRICES

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NON-ISOMORPHIC GROUPS WITH ISOMORPHIC SPECTRAL TABLES AND BURNSIDE MATRICES

It was shown by Formanek and Sibley that the group determined characterizes a finite groupG up to isomorphism. Hoehnke and Johnson (independelltly the suthors--using an argumentof Manslield) showed the corresponding result for k-characters, k = 1, 2, 3. The notion of kcharacters dates back to nobenius. They are determined by the group doterminaDt and maybe derived from the character table CT(G) provided one knows additionally the functionswhere C(C) = {Cg, g E G} denotes the set of conjugacy classes of G.The object of the paper is to present criteria for finite groups (more precisely for solublegroups G and H which are both semi-direct products of a similar type) when1. G and H have isomorphic spectral tables (i.e., they form a Brauer pair),2. G and H have isomorphic table of marks (in particular the Burnside rings are isomorphic),3. G and H have the same 2-characters.Using this the authors construct two non-iS.Omorphic soluble groups for which all these threerepresent at iont heor et ical invar taut s coincide.