Finding related result in mathematics Assume that I have a math problem, I want to find results, theorems (as much as I could find, in maximum number) relevant  to the problem, how can I do that efficiently?
For example, one way could be to look for the latest survey paper related problem, but I have seen that survey paper does not exist in every case.
Second example, is searching using key words, but it does not help in mathematics much, as search engines are  not compatible with mathematical notation... is there any technique to optimize search related to the specific topic or problem?
Is would be nice to have a optimized flow-chart for searching, collecting and compiling related to the problem or topic.
You're asking for the impossible.  Almost every mathematician with more than a few papers has had the experience of submitting a paper or circulating it as a preprint and having some relevant work they didn't know about (and are not expected to have known about) pointed out to them.
If you are asking about one or two specific narrow questions or equations/formulas, then usually the best thing to do is to figure out who the friendliest expert who might know is, and ask them.  Even if they don't know, they might refer you to another friendly expert.  (Some subsubsubfields have friendlier experts than others, and this difference definitely influences the popularity of the subsubsubfield.)
If you're looking to break into a new subsubsubfield with lots of history without an advisor, then some subsubsubfields have friendly conferences, but, in general, ...uhh... good luck.