English

$B$-rigidity of the property to be an almost Pogorelov polytope

Algebraic Topology 2020-08-04 v5 Combinatorics

Abstract

Toric topology assigns to each nn-dimensional combinatorial simple convex polytope PP with mm facets an (m+n)(m+n)-dimensional moment-angle manifold ZP\mathcal{Z}_P with an action of a compact torus TmT^m such that ZP/Tm\mathcal{Z}_P/T^m is a convex polytope of combinatorial type PP. We study the notion of BB-rigidity. A property of a polytope PP is called BB-rigid, if any isomorphism of graded rings H(ZP,Z)=H(ZQ,Z)H^*(\mathcal{Z}_P,\mathbb Z)= H^*(\mathcal{Z}_Q,\mathbb Z) for a simple nn-polytope QQ implies that it also has this property. We study families of 33-dimensional polytopes defined by their cyclic kk-edge-connectivity. These families include flag polytopes and Pogorelov polytopes, that is polytopes realizable as bounded right-angled polytopes in Lobachevsky space L3\mathbb L^3. Pogorelov polytopes include fullerenes -- simple polytopes with only pentagonal and hexagonal faces. It is known that the properties to be flag and Pogorelov polytope are BB-rigid. We focus on almost Pogorelov polytopes, which are strongly cyclically 44-edge-connected polytopes. They correspond to right-angled polytopes of finite volume in L3\mathbb L^3. There is a subfamily of ideal almost Pogorelov polytopes corresponding to ideal right-angled polytopes. We prove that the properties to be an almost Pogorelov polytope and an ideal almost Pogorelov polytope are BB-rigid. As a corollary we obtain that 33-dimensional associahedron As3As^3 and permutohedron Pe3Pe^3 are BB-rigid. We generalize methods known for Pogorelov polytopes. We obtain results on BB-rigidity of subsets in H(ZP,Z)H^*(\mathcal{Z}_P,\mathbb Z) and prove an analog of the so-called separable circuit condition (SCC). As an example we consider the ring H(ZAs3,Z)H^*(\mathcal{Z}_{As^3},\mathbb Z).

Keywords

Cite

@article{arxiv.2004.04873,
  title  = {$B$-rigidity of the property to be an almost Pogorelov polytope},
  author = {Nikolai Erokhovets},
  journal= {arXiv preprint arXiv:2004.04873},
  year   = {2020}
}

Comments

42 pages, 19 figures. In version 3 the results on $B$-rigid subsets are improved. As a corollary we obtain that any ideal almost Pogorelov polytope is $B$-rigid. In version 4 small inaccuracies in the abstract and in the introduction were corrected. In version 5 some references were added and some misprints were corrected