Spectral Graph Theory Lecture 7 Cheeger ’ s Inequality

نویسنده

  • Daniel A. Spielman
چکیده

Today, we will prove Cheeger’s Inequality. I consider it to be the most important theorem in spectral graph theory. Cheeger’s inequality has many variants, all of which tell us in some way that when λ2 of a graph is small, the graph has a cut of small conductance (or ratio or sparsity). Recall that in Lecture 5 we proved: Theorem 7.1.1. Let G = (V,E) be a graph and let LG be its Laplacian matrix. Let S ⊂ V and set σ = |S| / |V |. Then, |∂(S)| ≥ λ2 |S| (1− σ).

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تاریخ انتشار 2009