I read in Mirman's book on group theory that SO(2) is the only simple group that is not semisimple. Can anyone explain this in terms a beginner could understand? I'm not sure how this is possible based on what I've read. Simple groups would seem to be a special case of semisimple groups.(adsbygoogle = window.adsbygoogle || []).push({});

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# SO(2) simple but not semisimple?

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