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arXiv 2108.03037math.CO
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关于模式回避Motzkin路的generating functions

On the generating functions of pattern-avoiding Motzkin paths

Christian Bean, Antonio Bernini, Matteo Cervetti, Luca Ferrari

摘要:

利用递归方法,证明了避免单个(不一定是连续的)模式的Motzkin路径集的生成函数在$x$和Catalan生成函数$C(x) = \frac{1-\sqrt{1-4x^2}}{2x^2}$上是有理的,其中$x$跟踪路径的长度.此外,还提供了在更一般的任意模式集的情况下求生成函数的算法.此外,该算法允许我们找到一个组合规范的模式避免Motzkin路径,它不仅可以用于枚举,但也用于穷举和随机生成。

英文摘要:

Using a recursive approach, we show that the generating function for sets of Motzkin paths avoiding a single (not necessarily consecutive) pattern is rational over $x$ and the Catalan generating function $C(x) = \frac{1-\sqrt{1-4x^2}}{2x^2}$, where $x$ keeps track of the length of the path. Moreover, an algorithm is provided for finding the generating function in the more general case of an arbitrary set of patterns. In addition, this algorithm allows us to find a combinatorial specification for pattern-avoiding Motzkin paths, which can be used not only for enumeration, but also for exhaustive and random generation.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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