A polygon is an area formed from at least three vertexes (a triangle). These have a triangular shaped metallic core with argon bound at the vertexes. Core tensor contains elements formula 22 which are the vertexes of the system. At the vertexes are niches, alternatively rectangular and semicircular; one of them housed the entrance. The lake is roughly triangular in shape, with the vertexes pointing north, east, and south. That's because each processor only stores partial edge lists of vertexes.