OpenAI claim summary for Math-2413
mathematicsTop Open Problemscontributionliterature_reportClaim: literature report
Summary of a claim published in openai/math; not a claim by this platform.
Manuscript 1 (family 285, 2026-09-23): The infinite-order degree-zero assembly-kernel class for a finitely generated torsion-free discrete group directly refutes the universal coefficient-free reduced injectivity and isomorphism assertions, with no coefficient or maximal-completion substitution.
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Manuscript
Contents
Injectivity of the Baum–Connes Assembly Map
OpenAI's claim
For one finitely generated group without torsion, the coefficient-free reduced assembly map annihilates an infinite-order degree-zero K-homology class; this is claimed to refute rational injectivity. The cited manuscript argues for that result; its relation to this problem is specified below.Mathematical statement of the claimed result
Mathematical claim 1.
OpenAI claims a discrete group, torsion-free and finitely generated, $G$, an injection $i:\mathbb Z^2\hookrightarrow G$, and $c\in H^2(BG;\mathbb Z)$ such that \[ \langle(Bi)^*c,[T^2]\rangle=1,\qquad i_*\beta=0\text{ in }K_0(C_r^*(G)), \] here $\beta\in K_0(C_r^*(\mathbb Z^2))$ is the Bott generator chosen to have rank zero. The class $h=(Bi)_*[D_{T^2}]\in K_0(BG)$ has infinite order but satisfies $\mu_G^r(h)=0$. Here $\mu_G^r:K_*(BG)\to K_*(C_r^*(G))$ is reduced coefficient-free analytic assembly and $[D_{T^2}]$ is the oriented torus spin-Dirac class. This asserts failure of reduced assembly injectivity without coefficients, even rationally.Outline of the argument
Manuscript 1 (family 285, 2026-09-23): The construction embeds a torus subgroup with an integral cohomology detector while arranging disappearance of its Bott class analytically. Operators assembled on almost disjoint Cayley-graph sheets retain controlled spectral supports; estimates for the leftover forest permit the required homotopies in the reduced completion. A finite witness then restricts the construction to a finitely generated subgroup.Formal verification
Family 285 has no Lean scope page in this snapshot; no formalization of these manuscript results is listed.This site has not executed the Lean files or checked their dependencies. These descriptions report the scope of the linked declarations, rather than a new verification of the proofs.
Status caveat
OpenAI attributes these results to an internal model. Its release notice cautions that results lacking full formalization can contain mistakes. This site has not independently assessed the proofs; a solved label records the scope of the reported claim.Sources
- OpenAI, A torsion-free counterexample to reduced Baum–Connes injectivity, 2026-09-23; citation key
OAI:A-Torsion-Free-Counterexample-to-Reduced-Baum-Connes-Injectivity-September-23-2026. PDF (GitHub); PDF (direct); Manuscript page and citation; Latest version; Statement source: thm:main. - OpenAI catalogue entry.