Cavity and variational methods

This lecture covers the cavity method for the run-fill Ising model, focusing on computing the free entropy using phi and z. The instructor explains the importance of the cavity method in computing phi and how it relates to magnetization. The lecture also delves into the variational method, demonstrating how to use a factorized distribution to approximate the Boltzmann distribution. The instructor emphasizes the process of minimizing the parameter m to obtain the desired results. The lecture concludes with a detailed explanation of the entropy function and its application in the context of the Ising model.