Coincidence and Wilf-classification

Anders, Bjarki, Isak, Ingibjorg, Steinunn, Bridget, Tomas, Henning and Lina

Shading lemma Two patterns are coincident if they are avoided by the same permutations. They are Wilf-equivalent if the are avoided by the same number of permutations. We study general rules which can tell us when patterns (or sets of patterns) are coincident or Wilf-equivalent.