Functorial Alperin weight conjecture

Let kk be an algebraically closed field of characteristic p>0p>0, let F\mathbb{F} be an algebraically closed field of characteristic 00, and let (G,b)(G,b) be a group-block pair over kk. Let FBℓF,k\mathcal{F}\mathcal{B}\ell_{\mathbb{F},k} be the category of diagonal pp-permutation functors, let K0(FBℓF,k)K_0(\mathcal{F}\mathcal{B}\ell_{\mathbb{F},k}) be its Grothendieck group, and write [ ⁣[G,b] ⁣]F[\![G,b]\!]_{\mathbb{F}} for the class of the functor associated with (G,b)(G,b). Let Sp(G)\mathcal{S}_p(G), GσG_\sigma, ∣σ∣|\sigma|, bσb_\sigma, and d(b)d(b) be as in Alperin's blockwise weight conjecture. Finally, S1,1,FS_{\mathbf{1},1,\mathbb{F}} denotes the simple diagonal pp-permutation functor indexed by the trivial pp-group, the identity automorphism, and the trivial module.

Functorial Alperin weight conjecture. In K0(FBℓF,k)K_0(\mathcal{F}\mathcal{B}\ell_{\mathbb{F},k}),

∑σ∈[G\Sp(G)](−1)∣σ∣[ ⁣[Gσ,bσ] ⁣]F={[S1,1,F]if d(b)=0;0if d(b)>0.\sum_{\sigma\in [G\backslash \mathcal{S}_p(G)]}(-1)^{|\sigma|}[\![G_\sigma,b_\sigma]\!]_{\mathbb{F}}=\begin{cases}[S_{\mathbf{1},1,\mathbb{F}}]&\text{if }d(b)=0;\\0&\text{if }d(b)>0.\end{cases}

The paper formulates this as a functorial version of Alperin's blockwise weight conjecture and states that it is equivalent to the original conjecture. The source gives no independent resolution status.

References

Primary source

Robert Boltje, Serge Bouc and Deniz Yılmaz, “On Alperin's conjecture and functorial equivalence of blocks”, arXiv:2507.20314 (2025).

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