Sequences of Ordered Sets and Catalan Numbers |
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| Authors: | Alzohairi Mohammad |
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| Institution: | (1) Department of Mathematics, King Saud University, P. O. Box 2455, Riyadh, 11451, Saudi Arabia |
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| Abstract: | We define the down sets (lower covers, respectively) sequence of an ordered set. We show that the number of down set sequences of an n-ordered set is equal to the n-th Catalan Number. We give a characterization of down sets sequences of an ordered set and another characterization of lower covers sequences of an ordered set. |
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| Keywords: | Catalan numbers Down sets |
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