clopen.solutions

A positive-norm counterexample to a TC-weight question

Recorded by the registry's curators from GitHub; the authors did not submit it here.

Kaiwen Jin

Let $S$ be the closed oriented surface of genus two. The aspherical four-manifold $M=S\times S$ has a rational fundamental class of positive homological $\ell^1$ seminorm, but every nonzero $u\in H^4(M;\Q)$ satisfies $\wt(1\times u-u\times1)\le2$. This gives a negative answer to Neofytidis's question asking whether a positive-norm degree-$k$ class on a closed oriented aspherical manifold forces the existence of a nonzero degree-$k$ class with TC weight at least $k$.

Claims

SOLUTION CLAIMED OP-00823 — Maximal TC weight from positive homological norm
Counterexample · fidelity not yet established

Files and sources

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

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