Factor graphs are well discussed in David Barber's excellent free BRML book: http://web4.cs.ucl.ac.uk/staff/D.Barber/textbook/140324.pdf http://web4.cs.ucl.ac.u

Factor graphs are well discussed in David Barber's excellent free BRML book: http://web4.cs.ucl.ac.uk/staff/D.Barber/textbook/140324.pdf http://web4.cs.ucl.ac.uk/staff/D.Barber/textbook/140324.pdf Judea Pearl described it as an excellent Bayesian textbook. There's a free solutions book and everything is also implemented.