Small rational-object equality conjecture for finite groups

Let GG be a finite group. Let f(G)f(G) denote the number of irreducible characters of GG with rational fields of values, and let h(G)h(G) denote the number of conjugacy classes of GG with rational fields of values. Small rational-object equality conjecture. If

min{f(G),h(G)}5,\min\{f(G),h(G)\}\leq 5,

then

f(G)=h(G).f(G)=h(G).

The conjecture is motivated by computations of groups of order at most 128128, which found no counterexample with either f(G)5f(G)\leq 5 or h(G)5h(G)\leq 5. Whether the equality always holds under this bound remains open.

Sources & referencesView supporting material

Primary source

Juan Martínez Madrid and Marco Vergani, “Multiplicities of fields of values of conjugacy classes in finite groups”, arXiv:2508.16361 (2025).

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