通常，你只会在这两种情况下用替代法，或者这可以极大地简化被积函数，或者就是这可以简化，积分的上下限。

I mean, normally, you would only do this kind of substitution if either it simplifies a lot the function you are integrating, or it simplifies a lot the region on which you are integrating.

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嵌套的第二个SUM和EXTRACT函数组合计算下限，下限基于前面的片中的值的总数，在映射规则中表示为InSlice Index - 1。

The second, embedded combination of sum and EXTRACT function calculates the lower boundary, which is based on the sum of values in preceding slices, represented in the map rule as InSliceIndex - 1.

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给出并证明了一个函数的上下限及其几个推论。

The paper gives the upper-lower limit of a function and draws several deductions by proving them.

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