Finkelberg–Mirković conjecture for general blocks

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Let J⊂SaffJ\subset S_{\mathrm{aff}} be finitary, let CJC_J be the corresponding set of weights, and let λ∈CJ\lambda\in C_J. Let PervWhit,J(Gr∘,k)\mathsf{Perv}_{\mathrm{Whit},J}(\mathsf{Gr}^\circ,\Bbbk) be the indicated Whittaker-equivariant perverse-sheaf category, let RepWaff∙λ(G)\mathsf{Rep}_{W_{\mathrm{aff}}\bullet\lambda}(\mathbf G) be the corresponding representation block, and let ΔwJ\Delta_w^J, ∇wJ\nabla_w^J, ICwJ\mathscr I\mathscr C_w^J, M(w∙λ)\mathsf M(w\bullet\lambda), N(w∙λ)\mathsf N(w\bullet\lambda) and L(w∙λ)\mathsf L(w\bullet\lambda) denote the standard, costandard, intersection-cohomology, Weyl, dual Weyl and simple objects. For finitary J⊂KJ\subset K, let the averaging functors be the geometric counterparts of the translation functors TλμT_\lambda^\mu and TμλT_\mu^\lambda.

Finkelberg–Mirković conjecture. There exists an equivalence

Ψλ:PervWhit,J(Gr∘,k)→∼RepWaff∙λ(G)\Psi_\lambda:\mathsf{Perv}_{\mathrm{Whit},J}(\mathsf{Gr}^\circ,\Bbbk)\xrightarrow{\sim}\mathsf{Rep}_{W_{\mathrm{aff}}\bullet\lambda}(\mathbf G)

that sends, for every w∈WaffJw\in W_{\mathrm{aff}}^J, the three objects to the corresponding objects:

Ψλ(ΔwJ)≅M(w∙λ),Ψλ(∇wJ)≅N(w∙λ),Ψλ(ICwJ)≅L(w∙λ).\Psi_\lambda(\Delta_w^J)\cong\mathsf M(w\bullet\lambda),\quad \Psi_\lambda(\nabla_w^J)\cong\mathsf N(w\bullet\lambda),\quad \Psi_\lambda(\mathscr I\mathscr C_w^J)\cong\mathsf L(w\bullet\lambda).

It intertwines the geometric-Satake action with the action of Rep(G/Z(G))\mathsf{Rep}(G/\mathrm Z(G)). Moreover, the equivalences can be chosen so that, for finitary J⊂KJ\subset K, λ∈CJ\lambda\in C_J and μ∈CK\mu\in C_K, the translation functors correspond to the natural averaging functors.

This extends the conjecture of Finkelberg and Mirković from the principal block to general blocks. The supplied text does not state whether it has been resolved.

References

Primary source

Pramod N. Achar and Simon Riche, “Tilting modules for reductive algebraic groups: characters and support varieties”, arXiv:2511.05063 (2025).

Additional references

3 papers in this index state this conjecture (2020–2025). The statement above is taken from the most recent of them; the others are arXiv:2403.03734, arXiv:2004.14791.

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