Conjecture that Wilf equivalence implies enumerating equivalence for binary-tree patterns

Let ss and tt be patterns on binary trees. Two patterns are Wilf equivalent when their avoidance functions are equal, and they are enumerating equivalent when their enumerating generating functions are equal. The avoidance function of a pattern tt is Avt(x)=n1anxnAv_t(x)=\sum_{n\geq 1}a_nx^n, while its enumerating generating function is Ent(x,y)=n1,k0an,kxnykEn_t(x,y)=\sum_{n\geq 1,\,k\geq 0}a_{n,k}x^ny^k, where ana_n counts binary trees avoiding tt and an,ka_{n,k} counts those containing exactly kk copies of tt. Wilf-to-enumerating equivalence conjecture. If two patterns ss and tt are Wilf equivalent, then they are enumerating equivalent. Since Avt(x)=Ent(x,0)Av_t(x)=En_t(x,0), enumerating equivalence is a stronger condition than Wilf equivalence; the conjecture asserts that these two notions nevertheless coincide for such patterns.

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Primary source

Andrey T. Cherkasov and Dmitri Piontkovski, “Wilf classes of non-symmetric operads”, arXiv:2105.08880 (2021).

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