@conference{10902/34560, year = {2014}, url = {https://hdl.handle.net/10902/34560}, abstract = {We study a natural generalization of the noncrossing relation between pairs of elements in [n] to k-tuples in [n]. We show that the flag simplicial complex on ( [n] k ) induced by this relation is a regular, unimodular and flag triangulation of the order polytope of the poset given by the product [k] × [n − k] of two chains, and it is the join of a simplex and a sphere (that is, it is a Gorenstein triangulation). This shows the existence of a flag simplicial polytope whose Stanley-Reisner ideal is an initial ideal of the Graßmann-Plucker ideal, while previous constructions of such ¨ a polytope did not guaranteed flagness. The simplicial complex and the polytope derived from it naturally reflect the relations between Graßmannians with different parameters, in particular the isomorphism Gk,n ≅ Gn−k,n. This simplicial complex is closely related to the weak separability complex introduced by Zelevinsky and Leclerc.}, organization = {Supported by the Spanish Ministry of Science (MICINN) through grant MTM2011-22792, and by a Humboldt Research Award of the Alexander von Humboldt Foundation.}, publisher = {Episciences.org}, publisher = {Discrete Mathematics and Theoretical Computer Science, 2014, 609-620}, title = {Noncrossing sets and a Graßmann associahedron}, author = {Santos, Francisco and Stump, Christian and Welker, Volkmar}, }