PI=WI conjecture for character varieties

Let CC be a smooth projective curve and GG a reductive group. Let MB(C,G)M_{\mathrm{B}}(C,G) be the untwisted character variety, MDol(C,G)M_{\mathrm{Dol}}(C,G) its Dolbeault counterpart, and Ψ ⁣:MDol(C,G)MB(C,G)\Psi\colon M_{\mathrm{Dol}}(C,G)\to M_{\mathrm{B}}(C,G) the non-abelian Hodge diffeomorphism. Write IHIH^* for intersection cohomology, let PkP_k be the perverse Leray filtration associated with the Hitchin fibration, and let W2kW_{2k} be the weight filtration.

PI=WI conjecture. For every kk,

PkIH(MDol(C,G))=ΨW2kIH(MB(C,G)).P_k IH^*(M_{\mathrm{Dol}}(C,G))=\Psi^*W_{2k}IH^*(M_{\mathrm{B}}(C,G)).

The conjecture was proposed to recover curious hard Lefschetz for the singular untwisted character variety; together with relative hard Lefschetz, it would imply intersection curious hard Lefschetz. Its status is not resolved in the supplied text.

Sources & referencesView supporting material

Primary source

Mirko Mauri, “Intersection cohomology of rank two character varieties of surface groups”, arXiv:2101.04628 (2021).

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