For which pairs (m,n) does there exist an injective function f:R2→R2 under which the image of every regular m-gon is a regular n-gon. (Note that m,n≥3, and that by a regular N-gon we mean the union of the boundary segments, not the closed polygonal region.)Proposed by Sutanay Bhattacharya, Bishnupur, India combinatoricscombinatorial geometry