Sets having not more than two-valued metric projection onto a plane / A. A. Flerov. // Vestnik Moskovskogo Universiteta. Seriya 1. Matematika. Mekhanika. 2013. № 6. P. 14-19 [Moscow Univ. Math. Bulletin. Vol. 72, N 2, 2017. P. 0].
For a set M in the Euclidean plane R2, we prove that if any point x ∈ R2 has one or two closest points in M, then each point of the convex hull of M lies in the segment with endpoints in M.
Key words: metric projection, Bunt theorem.