Shape-Wilf-equivalences for vincular patterns

TL;DR

This paper extends the concept of shape-Wilf-equivalence to vincular patterns, introducing filling-shape-Wilf-equivalence and establishing new equivalences that generalize previous Wilf-equivalences, thereby advancing the understanding of pattern avoidance.

Contribution

It introduces filling-shape-Wilf-equivalence for vincular patterns and proves new equivalences, generalizing prior Wilf-equivalence results for generalized patterns.

Findings

Established filling-shape-Wilf-equivalence for certain pattern classes.

Proved that direct sum with a pattern preserves filling-shape-Wilf-equivalence.

Discovered new pairs of filling-shape-Wilf-equivalent patterns.

Abstract

We extend the notion of shape-Wilf-equivalence to vincular patterns (also known as "generalized patterns" or "dashed patterns"). First we introduce a stronger equivalence on patterns which we call filling-shape-Wilf-equivalence. When vincular patterns $\alpha$ and $\beta$ are filling-shape-Wilf-equivalent, we prove that the direct sum $\alpha\oplus\sigma$ is filling-shape-Wilf-equivalent to $\beta\oplus\sigma$. We also discover two new pairs of patterns which are filling-shape-Wilf-equivalent: when $\alpha$, $\beta$, and $\sigma$ are nonempty consecutive patterns which are Wilf-equivalent, $\alpha\oplus\sigma$ is filling-shape-Wilf-equivalent to $\beta\oplus\sigma$; and for any consecutive pattern $\alpha$, $1\oplus\alpha$ is filling-shape-Wilf-equivalent to $1\ominus\alpha$. These equivalences generalize Wilf-equivalences found by Elizalde and Kitaev. These new equivalences imply many new Wilf-equivalences for vincular patterns