Brady–McCammond's CAT(0) conjecture for the orthoscheme complex of non-crossing partitions

Let NC(n)\operatorname{NC}(n) be the lattice of non-crossing partitions, and let its orthoscheme complex be its simplicial realisation equipped with the orthoscheme metric obtained by identifying each maximal simplex with the nn-orthoscheme. Let Bn\mathcal{B}_n denote the braid group on nn strands. Brady–McCammond's conjecture. For every nn, the orthoscheme complex of NC(n)\operatorname{NC}(n) is CAT(0)\operatorname{CAT}(0), and consequently the braid group Bn\mathcal{B}_n is CAT(0)\operatorname{CAT}(0). This geometric formulation is motivated by the product decomposition of the relevant universal cover and the fact that CAT(0)\operatorname{CAT}(0) curvature of the orthoscheme complex would imply the required CAT(1)\operatorname{CAT}(1) link condition. The supplied text does not state whether the conjecture has been resolved.

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Primary source

Barbara Baumeister, Kai-Uwe Bux, Friedrich Götze, Dawid Kielak and Henning Krause, “Non-crossing partitions”, arXiv:1903.01146 (2019).

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