The+Art+of+M.C.+Escher

Many mathematics lessons have been built around the art of M. C. Escher (1898-1972). He is famous for his tesselations, as well as his representations of polyhedra and dimensionality and logic of space. Below is one of his more famous works, //Relativity//. As you look at this work, identify three mathematical concepts and explain how Escher used them in the sketch.