English

Hyperelliptic four-manifolds defined by vector-colorings of simple polytopes

Algebraic Topology 2026-02-27 v3 Combinatorics Geometric Topology

Abstract

Toric topology assigns to each simple convex nn-polytope PP with mm facets an nn-dimensional real moment angle manifold RZP\mathbb RZ_P with a canonical action of Z2m=(Z/2Z)m\mathbb Z_2^m=(\mathbb Z/2\mathbb Z)^m. We consider (non-necessarily free) actions of subgroups HZ2mH\subset \mathbb Z_2^m on RZP\mathbb RZ_P. The orbit space N(P,H)=RZP/HN(P,H)=\mathbb RZ_P/H has an action of Z2m/H\mathbb Z_2^m/H. For general nn we introduce the notion of a Hamiltonian C(n,k)C(n,k)-subcomplex in the boundary of an nn-polytope PP generalizing the notions of a Hamiltonian cycle (k=2k=2), Hamiltonian theta-subgraph (k=3k=3) and Hamiltonian K4K_4-subgraph (k=4)k=4) in the 11-skeleton of a 33-polytope. Each C(n,k)C(n,k)-subcomplex CPC\subset \partial P corresponds to a subgroup HCZ2mH_C\subset\mathbb Z_2^m such that N(P,HC)SnN(P,H_C)\simeq S^n. We prove that in dimensions n4n\leqslant 4 this correspondence is a bijection. Any subgroup HZ2mH\subset \mathbb Z_2^m defines a complex C(P,H)PC(P,H)\subset \partial P. We prove that each Hamiltonian C(n,k)C(n,k)-subcomplex CC(P,H)C\subset C(P,H) inducing HH corresponds to a hyperelliptic involution τCZ2m/H\tau_C\in\mathbb Z_2^m/H on the manifold N(P,H)N(P,H) (that is, an involution with the orbit space homeomorphic to SnS^n) and in dimensions n4n\leqslant 4 this correspondence is a bijection. We prove that for the geometries X=S4\mathbb X= \mathbb S^4, S3×R\mathbb S^3\times\mathbb R, S2×S2\mathbb S^2\times \mathbb S^2, S2×R2\mathbb S^2\times \mathbb R^2, S2×L2\mathbb S^2\times \mathbb L^2, and L2×L2\mathbb L^2\times \mathbb L^2 there exists a compact right-angled 44-polytope PP with a free action of HH such that the geometric manifold N(P,H)N(P,H) has a hyperelliptic involution in Z2m/H\mathbb Z_2^m/H, and for X=R4\mathbb X=\mathbb R^4, L4\mathbb L^4, L3×R\mathbb L^3\times \mathbb R and L2×R2\mathbb L^2\times \mathbb R^2 there are no such polytopes.

Keywords

Cite

@article{arxiv.2407.20575,
  title  = {Hyperelliptic four-manifolds defined by vector-colorings of simple polytopes},
  author = {Nikolai Erokhovets},
  journal= {arXiv preprint arXiv:2407.20575},
  year   = {2026}
}

Comments

38 pages, 1 figure. In new version a connection between Example 4.76 and a recent work by Bruno Martelli on the Ivansic link is described. Some misprints are corrected and small details added