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Answering a question of Gurevich, Graham proved that, given any δ>0, for any finite coloring of the plane, there is a triangle of area δ having all of its three vertices of the same color. Questions were asked about similar results for parallelograms, rhombuses etc. For any coloring of the plane, a trapezoid is called monochromatic if its four vertices have the same color. In this paper, we prove...
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