Let
be a set of points in the plane. Suppose that there exists a pair of points that cannot be joined by a polygonal line not passing through any point of
Let us call such a pair of points unjoinable. Prove that for each real
there exists an unjoinable pair of points separated by distance
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$(BUL 5)$ Let $Z$ be a set of points in the plane. Suppose that there exists a pair of points that cannot be joined by a polygonal line not passing through any point of $Z.$ Let us call such a pair of points unjoinable. Prove that for each real $r > 0$ there exists an unjoinable pair of points separated by distance $r.$
Školjka