Geometric Invariants and Strain

The total strain for a graph G could then be taken as the sum of the cycle contributions. 

Now we address the case of a surface S that is presumed to be embedded without self-intersection in Ej. To characterize the shape of S consider the curvatures along different directions at a point in the surface to have minimum and maximum values ki and 2 at that point. Then ° the Gaussian curvature (at that point of S) is defined as 

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