The Szilassi polyhedron is a heptahedron that is topologically equivalent to a torus and for which every
pair of faces has a polygon edge in common. The Szilassi
polyhedron has 14 polyhedron vertices, seven
faces, and 21 polyhedron edges, and is the dual polyhedron of the Császár
polyhedron. This polyhedron was discovered by L. Szilassi in 1977. In the
above illustration of the net, sides indicated by letters are connected with the
corresponding side indicated by the same letter but with a different number of primes.
Like the tetrahedron, each face of the Szilassi polyhedron
touches all other faces.
The skeleton of the Szilassi polyhedron is equivalent
to the Heawood graph, shown above.
