Dyck's surface

Definition
Dyck's surface is a compact non-orientable surface (see classification of compact non-orientable surfaces) defined in the following equivalent ways:


 * 1) It is the defining ingredient::connected sum of three copies of the defining ingredient::real projective plane.
 * 2) It is the connected sum of the real projective plane and the defining ingredient::Klein bottle (which itself is a connected sum of two real projective planes).
 * 3) It is the connected sum of the real projective plane and the 2-torus.