Tilings of convex polygons
Call a polygon rational if every pair of side lengths has rational ratio. We show that a convex polygon can be tiled with rational polygons if and only if it is itself rational. Furthermore we give a necessary condition for an arbitrary polygon to be tileable with rational polygons: we associate to any polygon a quadratic form , which must be positive semidefinite if is tileable with rational polygons.The above results also hold replacing the rationality condition with the following: a polygon...