【摘要】 通过对1到n的全部排列中突出元素(也称为左向右最大)进行双重计数，并且利用容斥原理，本文给出徐利治含有调和数组合恒等式的组合证明.同时也用计数方法证明了它的特殊形式——一个更加著名的含有调和数的交替符号恒等式.更多还原

【Abstract】 By conducting double-counting on the outstanding elements(also known as left-to-right maxima) in the total permutations of 1 through n, and exploiting the principle of inclusion-exclusion, this paper provides a combinatorial interpretation of L. C. Hsu’s combinatorial identity involving harmonic numbers, and gives a counting proof for its special form——a more famous alternating-sign identity involving harmonic numbers.更多还原