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math.CO2024
Enumeration of interval-closed sets via Motzkin paths and quarter-plane walks
Sergi Elizalde, Nadia Lafrenière, Joel Brewster Lewis +3
We find a generating function for interval-closed sets of the product of two chains poset by constructing a bijection to certain bicolored Motzkin paths. We also find a functional…
math.CO2024
Counting pattern-avoiding permutations by big descents
Sergi Elizalde, Johnny Rivera, Yan Zhuang
A descent of a permutation is called a big descent if ; denote the number of big descents of by . We study…