可堆叠和可交换排列
Stackable and queueable permutations
摘要：
在使用堆栈可获得的置换（避免模式312的置换）和使用队列可获得的置换（避免321的置换）之间存在自然的双射。这种双射等价于Simion和Schmidt在1985年描述的双射。我们认为，这种双射很可能早在1968年就被Knuth的《计算机程序设计的艺术》第1卷的读者发现了，如果Knuth没有给他的练习分配难度等级的话。
英文摘要：
There is a natural bijection between permutations obtainable using a stack (those avoiding the pattern 312) and permutations obtainable using a queue (those avoiding 321). This bijection is equivalent to one described by Simion and Schmidt in 1985. We argue that this bijection might well have been found back in 1968 by readers of volume 1 of Knuth's *The Art of Computer Programming*, if Knuth had not assigned difficulty ratings to his exercises.
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