标题： 组合学与玻色子正规排序：温和的介绍 显示英文标题

标题： Combinatorics and Boson normal ordering: A gentle introduction

摘要： 我们通过将其应用于玻色子数算符的幂和指数的正规排序，讨论了用于算符排序问题的一般组合框架。 该问题的解以贝尔数和斯特林数的形式给出，这些数用于列举集合的划分。 此框架揭示了排序问题与组合对象之间的内在关系，并展示了魏克定理的分析背景。 该方法可以很容易地从本文给出的简单示例推广到一大类算符。 显示英文摘要

摘要： We discuss a general combinatorial framework for operator ordering problems by applying it to the normal ordering of the powers and exponential of the boson number operator. The solution of the problem is given in terms of Bell and Stirling numbers enumerating partitions of a set. This framework reveals several inherent relations between ordering problems and combinatorial objects, and displays the analytical background to Wick's theorem. The methodology can be straightforwardly generalized from the simple example given herein to a wide class of operators.