常见函数类对复合运算的封闭性

The Closeness of Common Functions to the Compound Calculation

大学数学专业在讨论黎曼可积函数类、勒贝格可测函数类、勒贝格可积函数类的封闭性时,只讨论到四则运算,至多讨论到极限运算,而对复合运算一般不作详细讨论,这无疑是个缺憾,文章就这些重要函数类对复合运算的封闭性做一些讨论.

Four arithmetic operations and the ultimate operation are only discussed at the level of college mathematics learning when it comes to Riemann integrable function; Lebesque measurable function and the closeness of Lebesque integrable function. The compound calculation is not usually discussed in detail at this level, which is undoubtedly a pity. This paper makes an effort to discuss the closeness of these important functions to the compound calculation.