Assertion: polyhedron's number | /r/HasProperty | assigned to a number of other things
Facets:
Source sentences:
text: Then we notice that a number can be assigned to any polytope (and a number of other things) called its Euler characteristic ( c ), which is additive for disjoint sets, equal to 1 for a point and invariant in a topological homeomorphism (so that topologically equivalent things have the same c ).