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有一类排列问题,其中的若干元素在所有的排列中顺序不变,保持一定,我们称这种排列为有序排列。 对于有序排列数的计算,若运用分类原理考虑,往往过程很麻烦,且计算也相当繁琐,本文从其它数学原理的角度介绍一些求有序排列数的方法。 一、整体原理 从问题的整体加以考虑。能揭示问题的实质,对有序数列从整体加以分析可以看出,在排列中顺序保持一定的元素间实际是一种组合,因而有序排列是排列和组合的混合。
There is a sort of permutation problem in which some of the elements are invariant in order in all permutations and remain constant. We call this arrangement an orderly arrangement. For the calculation of ordered number, if using the classification principle to consider, the process is often cumbersome, and the calculation is also very cumbersome. This paper introduces some ways to find the ordered number from the perspective of other mathematical principles. First, the overall principle to consider the overall problem. The nature of the problem can be revealed. It can be seen from the analysis of the sequence of ordered numbers that it is actually a combination of elements that are kept sequentially in an arrangement, and that the ordered arrangement is a mixture of arrangement and combination.