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The Wu Characteristic

These are some slides about an exciting invariant for graphs, the Wu characteristic, a topological invariant with similar properties than Euler characteristic: it is multiplicative, invariant under Barycentric subdivisions, satisfies a Gauss-Bonnet and Poincare-Hopf formula. It also agrees with Euler characteristic on discrete manifolds without boundary. On discrete manifolds with boundary it is the Euler characteristic of the interior minus the Euler characteristic of the boundary. See the preprint http://arxiv.org/abs/1601.04533