Complex group algebras of the direct product of non-isomorphic Suzuki groups

In this paper, we prove that the direct product [Formula: see text], where [Formula: see text] are distinct numbers, is uniquely determined by its complex group algebra. Particularly, we show that the direct product [Formula: see text], where [Formula: see text]’s are distinct odd prime numbers, is uniquely determined by its order and three irreducible character degrees.

Maximal Length Projections in Group Algebras with Applications to Linear Rank Tests of Uniformity

Let \(G\) be a finite group, let \(\mathbb{C}G\) be the complex group algebra of \(G\), and let \(p \in \mathbb{C}G\). In this paper, we show how to construct submodules\(S\) of \(\mathbb{C}G\) of a fixed dimension with the property that the orthogonal projection of \(p\) onto \(S\) has maximal length. We then provide an example of how such submodules for the symmetric group \(S_n\) can be used to create new linear rank tests of uniformity in statistics for survey data that arises when respondents are asked to give a complete ranking of \(n\) items.

Recognition of PSL(2,p) ×PSL(2,p) by its complex group algebra

In [H. P. Tong-Viet, Simple classical groups of Lie type are determined by their character degrees, J. Algebra 357 (2012) 61–68] the following question arose: Question. Which groups can be uniquely determined by the structure of their complex group algebras? It is proved that every quasisimple group except covers of the alternating groups is uniquely determined up to isomorphism by the structure of [Formula: see text], the complex group algebra of [Formula: see text]. One of the next natural groups to be considered are the characteristically simple groups. In this paper, as the first step in this investigation we prove that if [Formula: see text] is an odd prime number, then [Formula: see text] is uniquely determined by the structure of its complex group algebra.

A characterization of PGL (2,pn) by some irreducible complex character degrees

For a finite group G, let cd(G) be the set of irreducible complex character degrees of G forgetting multiplicities and X1(G) be the set of all irreducible complex character degrees of G counting multiplicities. Suppose that p is a prime number. We prove that if G is a finite group such that |G| = |PGL(2,p) |, p ? cd(G) and max(cd(G)) = p+1, then G ? PGL(2,p), SL(2, p) or PSL(2,p) x A, where A is a cyclic group of order (2, p-1). Also, we show that if G is a finite group with X1(G) = X1(PGL(2,pn)), then G ? PGL(2, pn). In particular, this implies that PGL(2, pn) is uniquely determined by the structure of its complex group algebra.

Moore-Penrose inversion in complex contracted inverse semigroup algebras

It is shown that every element of the complex contracted semigroup algebra of an inverse semigroup S = S0 has a Moore-Penrose inverse, with respect to the natural involution, if and only if S is locally finite. In particular, every element of a complex group algebra has such an inverse if and only if the group is locally finite.