
Let \(\text{Irr}(G)\) be the set of all irreducible complex characters of a finite group \(G\). If \(k(G)\) is the class number of \(G\), then \(| \text{Irr} (G) | = k(G)\). Let \(T(G) = \sum_{\chi \in \text{Irr}(G)} \chi(1)\), \(f(G) = | G|^{-1} \times T(G)\). If \(H \leq G\) then \(f(H) \geq f(G)\) (this is an easy corollary of Frobenius reciprocity). Under some suppositions on degrees of irreducible characters the following inequality holds [see \textit{K. G. Nekrasov} and the author, ibid. 33, 333-354 (1986; Zbl 0649.20005)]: \(f(G/H) \geq f(G)\) for all normal subgroups \(H\) in \(G\) [see loc. cit.; Lemma 2.6]. The following conjecture was posed [see question 4.3 in ibid.]: (*) If \(H\) is normal in \(G\) then \(f(G/H) \geq f(G)\). In this note we give counterexamples to (*).
class number, Ordinary representations and characters, normal subgroups, irreducible complex characters, degrees of irreducible characters, finite group, Frobenius reciprocity, Arithmetic and combinatorial problems involving abstract finite groups
class number, Ordinary representations and characters, normal subgroups, irreducible complex characters, degrees of irreducible characters, finite group, Frobenius reciprocity, Arithmetic and combinatorial problems involving abstract finite groups
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