The perverse–weight correspondence conjecture for compactified Picards

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Let CC be a complex integral projective curve whose normalization has genus zero and whose unique planar singularity is locally given by f(x,y)=0f(x,y)=0. Let CptPic⁡/Λ\mathcal{C}\operatorname{ptPic}/\Lambda be the compactified Picard quotient, equipped with the perverse filtration PP and weight filtration WW on cohomology, and let QQ denote the filtration induced by the Quot-side description. Perverse–weight correspondence conjecture. The weight grading on gr⁡∗WH∗(CptPic⁡/Λ)\operatorname{gr}^{W}_*H^*(\mathcal{C}\operatorname{ptPic}/\Lambda) is supported in even degrees. Moreover, for all j,kj,k,

gr⁡j+kPgr⁡2kWH∗(CptPic⁡/Λ)≃gr⁡jQgr⁡2kWH∗(CptPic⁡/Λ).\operatorname{gr}^{P}_{j+k}\operatorname{gr}^{W}_{2k}H^*(\mathcal{C}\operatorname{ptPic}/\Lambda)\simeq\operatorname{gr}^{Q}_{j}\operatorname{gr}^{W}_{2k}H^*(\mathcal{C}\operatorname{ptPic}/\Lambda).

This strengthens Hilb-vs-Quot by identifying the perverse and Quot filtrations after a weight-dependent shift, and extends an unpublished conjecture of Yun beyond the unibranch case. Its general status is open.

References

Primary source

Oscar Kivinen and Minh-Tâm Quang Trinh, “The Hilb-vs-Quot Conjecture”, arXiv:2310.19633 (2025).

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