[ SmokeDetector ] All-caps answer, few unique characters in answer: Word problem: Working together by Lin on math.stackexchange.com

The questions Book for in-depth study of filters is not very specific about what exactly the OP wants. The OP was last seen in 2013, so they wil probably not come back to clarify the question. No answers posted there, one comment gives suggestion of some book.

Should the question be deleted? Or do you see possibility to improve it somehow to get it to some reasonable shape, so that it could be useful?

Or maybe it could be closed as a duplicate of the question linked in the comments?

@MartinSleziak I don't see a possibility for it to be a useful signpost to the other question. Also it's very much a dead question, in addition to being unspecific, so I've gone ahead and deleted it.

@DanielFischer Thanks. It is probably the best solution.