Question 1180033
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See this link


https://math.stackexchange.com/questions/3687605/the-function-f-mathbbr-to-mathbbr-satisfies-fx-fy-fx-y-x



From this link,   you may learn that the question was posted to   math.stackexchange.com   11   months ago . . . 



Since then,   it did not obtain any solution/progress and was   CLOSED.



Since I visit this site from time to time, I can confirm that their contingent/participants  

are prominent, advanced, competent and knowledgeable persons with dynamic minds . . .