“…The border points are (P 0 , Q 0 ) = (8, 0), (P 1 , Q 1 ) = (5, 2), (P 2 , Q 2 ) = (1, 5), (P 3 , Q 3 ) = (0, 7). For every H the line through (P H−1 , Q H−1 ) and (P H , Q H ) is an edge of triangle V H , and intersects each other triangle V h , since the slopes increase with increasing h by the ordering in (1).…”