Christian Stump

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We exhibit a canonical connection between maximal (0, 1)-fillings of a moon polyomino avoiding northeast chains of a given length and reduced pipe dreams of a certain permutation. Following this approach we show that the simplicial complex of such maximal fillings is a vertex-decomposable, and thus shellable, sphere. In particular, this implies a positivity(More)
We study bijections { Set partitions of type X } ˜ −→ { Set partitions of type X } • either the number of crossings and of nestings, • or the cardinalities of a maximal crossing and of a maximal nesting. In type D, the results are obtained only in the case of non-crossing and non-nesting set partitions. In all types, we show in particular that non-crossing(More)
In this paper, we count factorizations of Coxeter elements in well-generated complex reflection groups into products of reflections. We obtain a simple product formula for the exponential generating function of such factor-izations, which is expressed uniformly in terms of natural parameters of the group. In the case of factorizations of minimal length, we(More)
In this article we prove explicit formulae for the number of non-isomorphic cluster-tilted algebras of type˜A n in the derived equivalence classes. In particular , we obtain the number of elements in the mutation classes of quivers of type˜A n. As a by-product, this provides an alternative proof for the number of quivers mutation equivalent to a quiver of(More)
The FindStat project provides an online platform for mathematicians, particularly for combinatorialists, to gather information about combinatorial statistics and their relations. As of January 2014, the FindStat database contains 173 statistics on 17 combinatorial collections. Combinatorial statistics arise naturally all over mathematics. Before we give the(More)
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