why use factor graph why use a factor graph why use factor graph why using factor graph why is a factor graph useful why is factor graph useful when performing inference? why are factor graph used why use factor graph for inference why use graph factor in reasoning why use factor graph why a factor graph why is factor graph used for Bayesian inference why use a factor graph why use a factor graph instead of a Bayesian network why use factor graph for inference why use factor graph in predicting what to expect from a Bayesian network? what is factor graph for? why use factor graph why use factor graph why is factor graph useful?