منابع مشابه
Combinatorics of rational singularities
A normal surface singularity is rational if and only if the dual intersection graph of a desingularization satisfies some combinatorial properties. In fact, the graphs defined in this way are trees. In this paper we give geometric features of these trees. In particular, we prove that the number of vertices of valency ≥ 3 in the dual intersection tree of the minimal desingularization of a ration...
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Each positive rational number x > 0 can be written uniquely as x = a/(b − a) for coprime positive integers 0 < a < b. We will identify x with the pair (a, b). In this extended abstract we use rational Dyck paths to define for each positive rational x > 0 a simplicial complex Ass(x) = Ass(a, b) called the rational associahedron. It is a pure simplicial complex of dimension a− 2, and its maximal ...
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An pa, bq-Dyck path P is a lattice path from p0, 0q to pb, aq that stays above the line y “ a b x. The zeta map is a curious rule that maps the set of pa, bq-Dyck paths into itself; it is conjecturally bijective, and we provide progress towards proof of bijectivity in this paper, by showing that knowing zeta of P and zeta of P conjugate is enough to recover P . Our method begets an area-preserv...
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ژورنال
عنوان ژورنال: Advances in Applied Mathematics
سال: 2008
ISSN: 0196-8858
DOI: 10.1016/j.aam.2006.12.006