Displaying similar documents to “Ramsey theoretic consequences of some new results about algebra in the Stone-Čech compactification.”

Restricted partitions and q-Pell numbers

Toufik Mansour, Mark Shattuck (2011)

Open Mathematics

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In this paper, we provide new combinatorial interpretations for the Pell numbers p n in terms of finite set partitions. In particular, we identify six classes of partitions of size n, each avoiding a set of three classical patterns of length four, all of which have cardinality given by p n. By restricting the statistic recording the number of inversions to one of these classes, and taking it jointly with the statistic recording the number of blocks, we obtain a new polynomial generalization...

Pattern avoiding partitions and Motzkin left factors

Toufik Mansour, Mark Shattuck (2011)

Open Mathematics

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Let L n, n ≥ 1, denote the sequence which counts the number of paths from the origin to the line x = n − 1 using (1, 1), (1, −1), and (1, 0) steps that never dip below the x-axis (called Motzkin left factors). The numbers L n count, among other things, certain restricted subsets of permutations and Catalan paths. In this paper, we provide new combinatorial interpretations for these numbers in terms of finite set partitions. In particular, we identify four classes of the partitions of...