Enumerating $(\bf{2+2})$-free posets by indistinguishable elements
نویسندگان
چکیده
منابع مشابه
Enumerating (2+2)-free posets by the number of minimal elements and other statistics
A poset is said to be (2+ 2)-free if it does not contain an induced subposet that is isomorphic to 2+ 2, the union of two disjoint 2-element chains. In a recent paper, Bousquet-Mélou et al. found, using so called ascent sequences, the generating function for the number of (2+ 2)-free posets: P (t) = ∑ n≥0 ∏n i=1 ( 1− (1− t) ) . We extend this result by finding the generating function for (2+ 2)...
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ژورنال
عنوان ژورنال: Journal of Combinatorics
سال: 2011
ISSN: 2156-3527,2150-959X
DOI: 10.4310/joc.2011.v2.n1.a6