Complementation conjecture for Wilf equivalence of pattern pairs

From papers

Let π1otinΠk\pi_1 otin\Pi_k and π2otinΠl\pi_2 otin\Pi_l with kotinlk otin l. For a pattern π\pi, write πc\pi^c for its complement, and let Πl(π1)\Pi_l(\pi_1) denote the set of length-ll patterns avoided jointly with π1\pi_1. Complementation conjecture.

  1. If π2,π2cotinΠl(π1)\pi_2,\pi_2^c otin\Pi_l(\pi_1), then (π1,π2)(\pi_1,\pi_2) is Wilf equivalent to (π1,π2c)(\pi_1,\pi_2^c).
  2. If π2otinΠl(π1)\pi_2 otin\Pi_l(\pi_1) and π2cotinΠl(π1)\pi_2^c otin\Pi_l(\pi_1), then (π1,π2)(\pi_1,\pi_2) is Wilf equivalent to (π1c,π2c)(\pi_1^c,\pi_2^c).

The conjecture proposes symmetries between avoidance classes of pairs of set-partition patterns, motivated by cardinality computations for several (3,4)(3,4)- and (4,4)(4,4)-pattern pairs. Its general validity is not established in the supplied text.

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Sources & referencesView supporting material

Primary source

Emma Christensen, “Pattern Avoidance in Set Partitions”, arXiv:1807.09710 (2018).

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