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math.CO2026
The species of interval orders
Anders Claesson
We show that, in the ring of virtual species, \[ \mathcal{I}=\sum_{m\geq 0}(-1)^m\prod_{i=1}^{m}\bigl((E^{-1})^i-1\bigr), \] where is the species of interval orders a…
math.CO2026
Inversion monotonicity in subclasses of the 1324-avoiders
Anders Claesson, Svante Linusson, Henning Ulfarsson +1
A collection of patterns is called inversion monotone if , the number of -avoiding permutations of length with inversions, is weakly increasing i…
math.CO2024
Enumerative aspects of Caylerian polynomials
Giulio Cerbai, Anders Claesson
Eulerian polynomials record the distribution of descents over permutations. Caylerian polynomials likewise record the distribution of descents over Cayley permutations, where a Cay…