A gap conjecture for Sylow numbers

Let pp be an odd prime, and let GG be a finite group with subgroup HH. For a finite group XX, write up(X) u_p(X) for the number of Sylow pp-subgroups of XX. Gap conjecture for Sylow numbers. There \exists a rational number f(p)<1f(p)<1 such that, whenever up(H)<up(G) u_p(H)< u_p(G), one has

νp(H)f(p)νp(G).\nu_p(H)\leq f(p)\cdot\nu_p(G).

This conjecture asks for a uniform gap, depending only on the odd prime pp, between unequal Sylow numbers of a finite group and its subgroup. The surrounding discussion notes that equality in the general inequality νp(H)νp(G)\nu_p(H)\leq\nu_p(G) can occur, while the proposed statement concerns the case of strict inequality; no resolution is given in the source.

Sources & referencesView supporting material

Primary source

Robert M. Guralnick, Attila Maróti, Juan Martínez Madrid, Alexander Moretó and Noelia Rizo, “Fixed point ratios, Sylow numbers and coverings of p-elements in finite groups”, arXiv:2407.20355 (2024).

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