Sylow synchronization conjecture

For every finite group GG, every prime pp dividing ∣G∣|G|, and every Sylow pp-subgroup PP of GG, one has ∣Irr⁡p′(G)∣=∣Irr⁡p′(NG(P))∣|\operatorname{Irr}_{p'}(G)|=|\operatorname{Irr}_{p'}(N_G(P))|, where Irr⁡p′(H)\operatorname{Irr}_{p'}(H) denotes the set of irreducible complex characters of HH whose degrees are not divisible by pp, and NG(P)N_G(P) is the normalizer of PP in GG.

References

Primary source

arXiv

Additional references

Progress summary

Refreshed
Claimed solved

The conjecture has new proofs for broad special cases, while an earlier report claims the full statement was proved, but that claim has not been independently verified and the latest summary still calls the general problem open.

The conjecture is the finite-group representation-counting statement comparing a group with an appropriate Sylow normalizer. It is associated with McKay, who proposed it in 1972.

Known results

  • Isaacs proved the statement for a large class of finite groups.
  • Isaacs, Navarro, and Malle reduced the remaining cases to particular groups of Lie type.
  • Späth and Cabanes supplied the remaining correspondence required in the claimed full proof.

September 2026 good-case advance; claimed full proof reported in 2025

On September 23, 2026, Huang, Lisi, Rizzoli, and Sabatini reported a broad good-case theorem, including all symmetric and alternating groups; their summary says the general conjecture remains open. Separately, a February 19, 2025 report described Späth and Cabanes's claimed completion of the corresponding McKay conjecture for every finite group. That identification and proof remain unverified here.

Current status (as of September 2026): broad good-case and symmetric/alternating cases are reported as proved, the latest summary calls the general conjecture open, and a purported full McKay-conjecture resolution remains unverified.

Sources

Solutions 0

No solutions have been posted yet.