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The four-dimensional disc embedding conjecture and whether the free group is good

Theorem 1.1: there is a compact oriented smooth 4-manifold MM with immersed proper discs f1,…,fkf_1,\dots,f_k with embedded boundary circles and framed (even smoothly embedded) spheres gig_i satisfying λ(fi,gj)=δij\lambda(f_i,g_j)=\delta_{ij}, λ(gi,gj)=0\lambda(g_i,g_j)=0, μ~(gi)=0\widetilde\mu(g_i)=0, whose boundary circles bound no pairwise disjoint locally flat discs, in any relative homotopy class. Corollary 1.2: F2F_2, and every group containing it, is not good in the Freedman-Quinn sense. Corollary 1.3: the unrestricted topological surgery and s-cobordism assertions cannot both hold. The marked tensor companion proves the framing-preserving version. Not shown: which of surgery or s-cobordism fails, or that the Borromean rings are not A-B slice.

Exact FrontierDelta

Prior state unknown→disproved

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Occurred: Sep 24, 2026

Delta type: SOURCE CLAIM

Assumptions: VibeMathed verification: unreviewed. Publication: announcement. AI contribution: ai-discovered. VibeMathed editorial classifications, scores, notes, relations, and dataset structure are CC BY 4.0. Source statements and linked content retain their own rights.

Canonical aliases: The four-dimensional disc embedding conjecture and whether the free group is good · Disc embedding conjecture; is F2 good?

Confidence: Not scored

Registry verification: unreviewed · announcement · candidate

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Companion: A marked tensor obstruction to four-dimensional disk embedding evidence for this event

The four-dimensional disc embedding conjecture and whether the free group is good evidence for this event

VibeMathed record: The four-dimensional disc embedding conjecture and whether the free group is good evidence for this event

The four-dimensional disc embedding conjecture and whether the free group is good parent of this event

Freedman-Quinn, Topology of 4-manifolds (1990) evidence for this event

Theorem 1.1: there is a compact oriented smooth 4-manifold MM with immersed proper discs f1,…,fkf_1,\dots,f_k with embedded boundary circles and framed (even smoothly embedded) spheres gig_i satisfying λ(fi,gj)=δij\lambda(f_i,g_j)=\delta_{ij}, λ(gi,gj)=0\lambda(g_i,g_j)=0, μ~(gi)=0\widetilde\mu(g_i)=0, whose boundary circles bound no pairwise disjoint locally flat discs, in any relative homotopy class. Corollary 1.2: F2F_2, and every group containing it, is not good in the Freedman-Quinn sense. Corollary 1.3: the unrestricted topological surgery and s-cobordism assertions cannot both hold. The marked tensor companion proves the framing-preserving version. Not shown: which of surgery or s-cobordism fails, or that the Borromean rings are not A-B slice. parent of this event

Kim-Orson-Park-Ray, Open problems, in The Disc Embedding Theorem (2021) evidence for this event

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