Permutations Generated by a Depth 2 Stack and an Infinite Stack in Series are Algebraic

[摘要] We prove that the class of permutations generated by passing an ordered sequence $12\dots n$ through a stack of depth 2 and an infinite stack in series is in bijection with an unambiguous context-free language, where a permutation of length $n$ is encoded

[学科分类] 离散数学和组合数学

[关键词] Pattern avoiding permutation;Algebraic generating function;Context-free language