Dokážeme, že každý 3-souvislý graf různý od K_4 obsahuje lehkou kontrahovatelnou hranu. Důsledkem je, že každý 3-polytop lze vztvořit ze čtyřstěnu dělením vrcholů stupně nejvýše 11. (cs)
We show that every 3-connected planar graph distinct from K_4 contains an edge that is both light and contractible. A consequence is that every 3-polytope can be constructed from tetrahedron by a sequence of splittings of vertices of degree at most 11.
We show that every 3-connected planar graph distinct from K_4 contains an edge that is both light and contractible. A consequence is that every 3-polytope can be constructed from tetrahedron by a sequence of splittings of vertices of degree at most 11. (en)