clopen.solutions

A finite three-ample complex with a nontrivial fundamental group

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Kaiwen Jin

We construct a finite three-ample simplicial complex on $32{,}768$ vertices which retracts simplicially onto a four-cycle. Thus the prescribed extension of every subcomplex on at most three vertices is compatible with a nontrivial fundamental group in a finite complex. The construction fixes a four-cycle and chooses the remaining permitted faces probabilistically. A finite union bound proves that all extension requests can be met at once.

Claims

SOLUTION CLAIMED OP-00792 — A finite three-ample complex with nontrivial fundamental group
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Files and sources

Paper
AIM @ 24edaad, paper/finite_three_ample.pdf ↗
Posted on GitHub
14 October 2026

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