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Discrete Mathematics & Theoretical Computer Science |
For an arbitrary Coxeter group $W$, David Speyer and Nathan Reading defined Cambrian semilattices $C_{\gamma}$ as certain sub-semilattices of the weak order on $W$. In this article, we define an edge-labelling using the realization of Cambrian semilattices in terms of $\gamma$-sortable elements, and show that this is an EL-labelling for every closed interval of $C_{\gamma}$. In addition, we use our labelling to show that every finite open interval in a Cambrian semilattice is either contractible or spherical, and we characterize the spherical intervals, generalizing a result by Nathan Reading.
Source : ScholeXplorer
IsRelatedTo ARXIV 1501.02619 Source : ScholeXplorer IsRelatedTo DOI 10.1016/j.crma.2015.12.004 Source : ScholeXplorer IsRelatedTo DOI 10.48550/arxiv.1501.02619
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