It also provides a mechanism to perform full Boolean queries against these Categories (e.g. ANDs and ORs).

它还提供了一种机制可以对这些类别执行全部的布尔操作(如，AND和OR)。

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We discussed the problems with Boolean notation in Chapter 2. We determined that just because the program needs to understand Boolean queries, users shouldn't be forced to as well.

我们在第2章中讨论过布尔符号存在的问题，我们认为，不能因为程序需要理解布尔查询，所以也迫使用户去理解它。

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