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4. Provable algorithms at the KS threshold

    1. Analyze BP

      Problem 4.1.

      [Elchanan Mossel] For the symmetric 2-groups SBM, show that BP (with random initialization) achieves $\varepsilon$ correlation with the truth, above the KS bound.
        • BP with good initialization

          Problem 4.2.

          [Lenka Zdeborová] Run BP with a ‘good’ initialization (e.g. using a spectral method based on the non-backtracking walk matrix). Show that it achieves the optimal overlap with the truth.
            • Analyze Gibbs sampling

              Problem 4.3.

              [Lenka Zdeborová] For the symmetric 2-groups SBM, show that Gibbs sampling achieves $\varepsilon$ correlation with the truth, above the KS bound.

                  Cite this as: AimPL: Connecting communities via the block model, available at http://aimpl.org/blockmodel.