Geometric realisation over aspherical groups
Abstract
We prove that the direct sums of extensions of scalars of relation modules are geometrically realisable as the second homotopy group of a finite 2-complex. We use this to exhibit a finite 2-complex with fundamental group the $(10,15)$ torus knot group and non-free $\pi_2$, yielding exotic presentations of a group for which no such examples had previously been known. We conclude by constructing stably free non-free modules over an infinite family of Baumslag-Solitar groups; it remains to determine whether these modules are geometrically realisable by finite 2-complexes.
- Publication:
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arXiv e-prints
- Pub Date:
- December 2023
- DOI:
- 10.48550/arXiv.2312.02948
- arXiv:
- arXiv:2312.02948
- Bibcode:
- 2023arXiv231202948T
- Keywords:
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- Mathematics - Algebraic Topology;
- Mathematics - Group Theory;
- Mathematics - Geometric Topology;
- Mathematics - Rings and Algebras;
- Primary 57M20;
- Secondary 57M05
- E-Print:
- 18 pages. Comments welcome