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arXiv math/0603405math.CO
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几个组合不等式的微积分证明

Calculus proofs of some combinatorial inequalities

Tomislav Došlić, Darko Veljan

摘要:

使用微积分,我们展示了如何证明一些组合不等式的类型对数凸或对数凸。证明了二项式系数和第一、第二类Stirling数是对数凹的,Motzkin数和秩为1的二级结构数是对数凸的.事实上,我们通过微积分证明了一个更强的结果,即Motzkin数和二级结构递归的自然连续"拼凑“(即相应的动力系统)是增函数。我们指出如何证明一般二级结构的对数凸性的渐近。我们的方法也适用于显示序列的值的一些正交多项式,特别是中央Delannoy数的序列,是对数凸的。

英文摘要:

Using calculus we show how to prove some combinatorial inequalities of the type log-concavity or log-convexity. It is shown by this method that binomial coefficients and Stirling numbers of the first and second kinds are log-concave, and that Motzkin numbers and secondary structure numbers of rank 1 are log-convex. In fact, we prove via calculus a much stronger result that a natural continuous ``patchwork'' (i.e. corresponding dynamical systems) of Motzkin numbers and secondary structures recursions are increasing functions. We indicate how to prove asymptotically the log-convexity for general secondary structures. Our method also applies to show that sequences of values of some orthogonal polynomials, and in particular the sequence of central Delannoy numbers, are log-convex.

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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