控制问题中不确定因素的变化范围通常是有界的，因此可把不确定性描述为“集”，从而能用集合论方法讨论不确定性系统。

In control problems the uncertain variables are often bounded, thus uncertainty can be spoken of as "sets" and uncertain systems can be studied by the methods of set theory.

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作为应用，证明了任意有界变差函数都与某可微函数在除过测度任意小的集合外重合。

It is also proved as application that any bounded variation function can be seen as a differentiable function beside a set of arbitrary small measure.

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