03-01-2013, 03:53 PM
Tutorial on Factor Graph and Belief Propagation
Tutorial on Factor.pdf (Size: 96.6 KB / Downloads: 85)
Factor Graph and Expression Tree
² Each factor node sums over all the variables that are its children,
since they are not related to any other function
Each variable node combines all its children factors
Computing All Marginal Functions
Each node sends message on an edge only when it has received
messages from all other edges.
Example: Kalman Filter (again)
Factor Graphs with Cycles
Iterative Processing
LDPC codes
RA codes
...
Message-passing Schedules
flooding
serial
Bethe Method
Bethe method: a special method of defining the regions and the
counting numbers.
Fixed points of the BP algorithm correspond to stationary points of the
Bethe approximation of the free energy.
BP always have a fixed point
Uniqueness of the stationary points is studied in physics.
BP does not decrease Bethe free energy at each iteration.
Generalized BP.