Currently there are three tags about K-theory: k-theory, algebraic-k-theory and topological-k-theory. The last two seem straightforward enough, but it's not clear to me what the standalone k-theory should be used for.
There has already been a discussion about these tags, but it was about getting rid of the tag altogether (and it's from ancient dark times of MSE). It didn't result in the deletion of the tag, based on the argument that some questions are about K-theory while not being about either algebraic or topological K-theory. Could someone knowledgeable enough clarify what these questions are, and edit the k-theory tag wiki accordingly?
My intuition is that the three tags are probably mutually exclusive: either the question is about topological K-theory, about algebraic K-theory, or about K-theory but neither topological or algebraic. Is that the case? If so, this should be clarified too, I think.
Currently, there are 23 questions tagged k-theory but neither algebraic-k-theory nor topological-k-theory. Some of them are simply lacking the correct tag, so that leaves very few questions in the complement, and the majority seem to be about operator/C* K-theory (I'm far from an expert on that so I may be mistaken though).