Solution

ID: past-exam-of-the-geometry-course-of-the-university-of-oxford/2011/1/a/solution

For a finite CW complex with vertices, edges and faces,
This Euler characteristic is unchanged by subdividing an edge, which adds one vertex and one edge, or subdividing a face by an edge, which adds one edge and one face. Common refinements therefore give the same value for different subdivisions of the same surface.

New to topics? Read the docs here!