The Euler characteristic is a topological invariant that provides a numerical value representing the shape or structure of a topological space. It is calculated using the formula $$ ext{χ} = V - E + F$$, where $$V$$ is the number of vertices, $$E$$ is the number of edges, and $$F$$ is the number of faces in a polyhedron. This concept connects deeply with the Gauss-Bonnet theorem, which relates the geometry of a surface to its topology through this characteristic.
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