It is known that the "pattern containment" order on permutations is not a partial well-order. Nevertheless, many naturally defined subsets of permutations are partially ...
Abstract. Consider, for a permutation Sk, the number F(n, ) of permutations in Sn which avoid as a subpattern. The conjecture of Stanley and Wilf is that for every there is a c...
Abstract. A pattern class is a set of permutations closed under pattern involvement or, equivalently, defined by certain subsequence avoidance conditions. Any pattern class X which...
We prove that the set of permutations generated by a stack of depth two and an infinite stack in series has a basis (defining set of forbidden patterns) consisting of 20 permutati...