The PI=WI conjecture for singular character varieties

Let r,nr,n be integers with r>0r>0, not necessarily coprime, and let MB(r,n)\mathcal{M}_{B}(r,n) and MDol(r,n)\mathcal{M}_{Dol}(r,n) be the Betti and Dolbeault moduli spaces. Let ψ:MB(r,n)MDol(r,n)\psi:\mathcal{M}_{B}(r,n)\to\mathcal{M}_{Dol}(r,n) be the real analytic nonabelian Hodge isomorphism, and let PP_\bullet and WW_\bullet denote the perverse and weight filtrations on intersection cohomology. PI=WI conjecture. The induced isomorphism

ψ:IH(MDol(r,n),Q)IH(MB(r,n),Q)\psi^*:IH^*(\mathcal{M}_{Dol}(r,n),\mathbb{Q})\to IH^*(\mathcal{M}_{B}(r,n),\mathbb{Q})

should satisfy, for every kZk\in\mathbb{Z},

PkIH(MDol(r,n),Q)W2kIH(MB(r,n),Q).P_kIH^*(\mathcal{M}_{Dol}(r,n),\mathbb{Q})\xrightarrow{\simeq}W_{2k}IH^*(\mathcal{M}_{B}(r,n),\mathbb{Q}).

This is the proposed singular analogue of P=W, replacing ordinary cohomology by intersection cohomology because the moduli spaces are generally singular in the noncoprime case. The source cites evidence from complex-structure independence of the perverse filtration, but gives no resolution of the conjecture.

Sources & referencesView supporting material

Primary source

Camilla Felisetti, “P=W phenomena in algebraic and enumerative geometry”, arXiv:2309.15061 (2024).

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