Panyushev's order conjecture for the positive Panyushev map

From papers

Let WW be a finite, crystallographic Coxeter group with Coxeter number hh, let mm be the parameter from the preceding theorem, and let P+{\sf P}_+ be the positive Panyushev map on NN+(W)N\kern-1ptN_+(W). Write R\mathcal{R} for the set of reflections, S\mathcal{S} for the set of simple reflections, ψ\psi for the relevant involution, and ε\varepsilon for the identity map. Panyushev's conjecture. The order of P+{\sf P}_+ is given by

ord(P+)={(m+1)h2,if ψRS≢ε,(m+1)h/21,if ψRSε.{\operatorname{ord}}({\sf P}_+) = \begin{cases} (m+1)h - 2, & \text{if } \psi|_{\mathcal{R} \setminus \mathcal{S}} \text{${}\not\equiv{}$} \varepsilon, \\ (m+1)h/2 - 1, & \text{if } \psi|_{\mathcal{R} \setminus \mathcal{S}} \equiv \varepsilon. \end{cases}

This is the positive analogue of Panyushev's conjecture on the order of the Panyushev map, whose non-positive version was proved by Armstrong, Stump, and Thomas. The supplied text does not establish whether this positive version has been resolved.

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Sources & referencesView supporting material

Primary source

Christian Krattenthaler and Christian Stump, “Positive m-divisible non-crossing partitions and their Kreweras maps”, arXiv:2506.14996 (2025).

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