Simple question: should the tagging of a question cover answers?

• pointers to literature
• algorithms
• examples
• counterexamples
• $\cdots$

should the tagging of the question be updated to cover what is in the (correct) answers, resp. is it already or should it be possible to tag questions directly?

• Just to clarify, is this only about "meta tags" (such as reference-request or counterexamples) or also about tags with actual mathematical content. (For example, are you also asking whether if after an answers is posted it becomes clear that the question is related to infinitary combinatorics and in the question the relation to this are is not clear, then the corresponding tag should be given.) – Martin Sleziak Apr 10 '18 at 11:05
• @MartinSleziak it is primarily about metatags, but if the answer exhibits connections to other areas of mathematics, I would also think that adding those tags could be helpful. – Manfred Weis Apr 10 '18 at 11:09
• I will mention that there were some related discussions on other metas (although not primarily about meta tags - if I may use that name). Here are examples from Mathematics Meta and Meta Stack Exchange: Retagging after an answer is given, Should I retag a question with a tag that is based on the answer and not the question? and Should we retag questions with topics proposed in the answers? – Martin Sleziak Apr 10 '18 at 11:26
• The meta-tags (counter)examples and reference-request sound to me of limited interest: the first is often completely useless (applies to too many questions); the second at least has the role of saying that the primary intention of the OP is to get references, rather than, say, a proof/construction. So this utility would not apply to mean that an answer provides a reference. "algorithm" is another problem (whether is should be called a meta-tag is questionable). – YCor Apr 13 '18 at 6:01
• In the case of meta-tags my opinion to your question is clearly no: completely useless. On the other hand adding a mathematical tag because an answer shows a connection unexpected by the OP (e.g., adding "lo.logic" because one realizes that many people in logic have thought about the question, etc) has the effect of making the post visible to potentially interested users and therefore can be a good idea. – YCor Apr 13 '18 at 6:05
• @YCor contrary to your opinion, I don't believe that metatags for answers are completely useless if one has the idea of scrutinizing MO for interesting algorithms, examples, counterexamples, etc. Such searches will be more effective, if it is possible to tell that it is in the answers or if the OP was looking for it. In a nutshell the metatags in answers would provide search keys for improved database functionality. – Manfred Weis Apr 14 '18 at 4:14
• @ManfredWeis I didn't claim "algorithm" is useless, about it I only said it's not clear that it's a meta-tag. Concerning examples/counterexamples (which are essentially equivalent), there are 410+115 questions with such tags... it's probably less that 10% than the number of actual questions asking for an example of something. – YCor Apr 14 '18 at 6:04