The Structural EM Procedure
Input: B0 = (G0,?0)
loop for n = 0,1,… until convergence
Improve parameters:
?`n = Parametric-EM (Gn,?n )
let B`n= (Gn`,?`n)
Improve structure:
Search for a network Bn+1 = (Gn+1,?n+1) s.t.
E[Score(Bn+1:D) | B`n] > E[Score(B`n:D) | B`n]
Parametric-EM() can be replaced by Gradient Ascent, Newton-Raphson methods, or accelerated EM.
Early stopping parameter optimization stage avoids “entrenchment” in current structure.