abstract: (1) Codes on graphs as a Markov Random Field. Examples of Markov Random Fields from combinatorial optimizationdecision problems, and statistical mechanics. Factor graph description. Free energy and Gibbs free energy. Threshold phenomena (phase transitions).
(2) A toy model: the ferromagnetic Ising model on random graphs. Belief propagation as an algorithm for computing marginals. Belief propagation as a proof technique. Bethe free energy.
(3) Phase diagram of LDPC ensembles. GEXIT functions, and generalized area theorems. The threshold for MAP (Maximum a Posteriori Probability) decoding.
(4) continuation from the previous lecture if necessary Solving large optimization problems through belief propagation: the example of independent sets.
(5) Proliferation of pure states. Algorithmic consequences.
(6) Dynamics. Local search algorithms: application (and analysis) for coding and optimization.