Mikä on roomalainen pinta?
The Roman surface or Steiner surface is a self-intersecting mapping of the real projective plane into three-dimensional space, with an unusually high degree of symmetry. This mapping is not an immersion of the projective plane; however, the figure resulting from removing six singular points is one. Its name arises because it was discovered by Jakob Steiner when he was in Rome in 1844.
self-intersecting mapping of the real projective plane into three-dimensional space, with an unusually high degree of symmetry