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Using standard double-coset formulas to obtain general-n results for Sylow double cosets in Sn

Develop methods that employ the orbit–stabilizer formula (2.4) and the standard double-coset enumeration formulas (2.5a), (2.5b), and (2.5c) to derive general-n results about the number and sizes of double cosets in Pn \ Sn / Pn, beyond example-driven computations.

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Background

The paper reviews standard formulas for counting double cosets, including the orbit–stabilizer approach and character-theoretic and class-sum formulas. These tools are classical and, in principle, applicable to H \ G / K problems.

However, the authors report that, despite these formulas being useful for preliminary computations and examples, they did not lead to general results in the setting of Pn \ Sn / Pn, indicating a methodological gap that invites further development.

References

All of these formulas were useful in our preliminary work, collecting examples. We have not seen how to use any of them to derive results for general n.

On the number and sizes of double cosets of Sylow subgroups of the symmetric group (2504.01149 - Diaconis et al., 1 Apr 2025) in Section 2.2