Generalized Bloch conductor formula

Let AA) be a complete discrete valuation ring with algebraically closed residue field kk, let S=Spec(A)S=\operatorname{Spec}(A), and let p:XSp:X\to S be a flat, generically smooth, regular SS-scheme of finite type whose singular locus ZZ is proper over SS. Write s=Spec(k)s=\operatorname{Spec}(k), let XsX_s be the special fiber, and fix a prime number \ell different from the residue characteristic. Let Φ=Φp(Q,X)\Phi=\Phi_p(\mathbb{Q}_{\ell,X}) be the \ell-adic complex of vanishing cycles. The notation \Bl(X/S)\Bl(X/S) denotes the Bloch intersection number, while χ\chi and Sw\operatorname{Sw} denote the Euler characteristic and Swan conductor, respectively.

Generalized Bloch conductor formula. If p:XSp:X\to S is an arithmetic SS-scheme with SS-proper singular locus ZZ, then

\Bl(X/S)=χ(H\et(Xs,Φ))Sw(H\et(Xs,Φ)).\Bl(X/S)=-\chi\bigl(\operatorname H^*_{\et}(X_s,\Phi)\bigr)-\operatorname{Sw}\bigl(\operatorname H^*_{\et}(X_s,\Phi)\bigr).

This generalizes Bloch's conductor formula from proper arithmetic schemes to arithmetic schemes whose singular locus is proper over the base. It relates an algebro-geometric intersection number to topological and arithmetic invariants of vanishing cycles; the supplied text does not state whether the conjecture is resolved.

Sources & referencesView supporting material

Primary source

Dario Beraldo and Massimo Pippi, “Categorification of the localized intersection product and Bloch conductor formula”, arXiv:2511.10527 (2025).

Additional references

2 papers in this index state this conjecture (2022–2025). The statement above is taken from the most recent of them; the others are arXiv:2211.11717.

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