Face Rings of Cycles, Associahedra, and Standard Young Tableaux

نویسنده

  • Anton Dochtermann
چکیده

We show that Jn, the Stanley-Reisner ideal of the n-cycle, has a free resolution supported on the (n−3)-dimensional simplicial associahedron An. This resolution is not minimal for n > 6; in this case the Betti numbers of Jn are strictly smaller than the f -vector of An. We show that in fact the Betti numbers βd of Jn are in bijection with the number of standard Young tableaux of shape (d + 1, 2, 1n−d−3). This complements the fact that the number of (d− 1)-dimensional faces of An are given by the number of standard Young tableaux of (super)shape (d+ 1, d+ 1, 1n−d−3); a bijective proof of this result was first provided by Stanley. An application of discrete Morse theory yields a cellular resolution of Jn that we show is minimal at the first syzygy. We furthermore exhibit a simple involution on the set of associahedron tableaux with fixed points given by the Betti tableaux, suggesting a Morse matching and in particular a poset structure on these objects.

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عنوان ژورنال:
  • Electr. J. Comb.

دوره 23  شماره 

صفحات  -

تاریخ انتشار 2016