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Positivity of Serre's Intersection Multiplicity

OpenAI · September 23, 2026

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Abstract

We prove Serre's positivity conjecture, including ramified mixed characteristic. If two nonzero finitely generated modules over a regular local ring have tensor product of finite length and complementary dimensions, then their intersection multiplicity is strictly positive.

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work in progress

Collected automatically by AI tools (Claude Opus 5.5 and GPT-6 Astra, 2026-10-21) and not checked by a person. May be wrong or incomplete. Report an error.

Comments and discussion

Formalization

  • unaoya (GitHub), SerrePositivity (GitHub repository, accessed 2026-10-21). An early-stage independent Lean 4 project to formalize this paper, with Theorem 1.1 stated with sorry and the paper's Theorems 3.1 and 4.7 planned as named axioms; a sorry-free core step derives $\chi>0$ only from an assumed input bundle.
  • mo271 (GitHub), Wikipedia/SerreMultiplicityConjectures: the positivity conjecture is true (google-deepmind/formal-conjectures issue #6911, 2026-10-07, open, label "solution found"). Proposes marking intersectionMultiplicity_pos and intersectionMultiplicity_pos_quotient as solved on the basis of this paper; the author says the comparison was prepared with AI assistance and should be checked against the Lean statements.
  • j2d9w5xtjn-png, feat: add Serre's multiplicity conjectures (google-deepmind/formal-conjectures PR #5382, merged 2026-09-23). This independent, AI-assisted contribution defines intersection multiplicity and states the module and prime-quotient positivity conjectures, without formalizing the manuscript's proof. [AI-generated per source]
  • Formal Conjectures authors, FormalConjectures/Wikipedia/SerreMultiplicityConjectures.lean (google-deepmind/formal-conjectures, accessed 2026-10-21). Lean statements of Serre's conjectures, all with sorry proofs; the general positivity statements that Theorem 1.1 addresses are still tagged research open, and the equicharacteristic and unramified cases are tagged solved.

Digests and expositions

Elsewhere

Independent sites; their content is not reviewed here.

Cite

@misc{OAI:Positivity-of-Serres-Intersection-Multiplicity-September-23-2026,
  author = {{OpenAI}},
  title = {{Positivity of Serre's Intersection Multiplicity}},
  howpublished = {OpenAI Math Release preprint
                  \href{https://github.com/openai/math/blob/main/preprints/Positivity-of-Serres-Intersection-Multiplicity-September-23-2026/paper.pdf}{OAI:Positivity-of-Serres-Intersection-Multiplicity-September-23-2026}},
  year = {2026}
}

Family 193: Serre’s intersection-multiplicity conjecture

Proves strict positivity of Serre's intersection multiplicity $\chi^R(M,N)$ for nonzero finitely generated modules over any regular local ring, provided $M\otimes_R N$ has finite length and $\dim M+\dim N=\dim R$. This resolves the positivity conjecture, including ramified mixed characteristic.

This is the only paper in this family.