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The Theory of Groups is a branch of mathematics in which one does something to something and then compares the result with the result obtained from doing the same thing to something else, or something else to the same thing.
群论是数学的一个分支，一个人对某物做某件事，然后将结果与做同一件事对另一件事或另一件事对同一件事所得到的结果进行比较。