Consider the joint distribution P(A, B, C, D) defined by the Bayes net in Figure S13.33. Compute the values of the following quantities: 

a. P(A = true). 

b. P(A = true, B = false, C = false, D = true). 

c. P(A = true, B = false, C = false, D = true).

Figure S13.33

B +b +b -b -b A +a -a C +C -C +C -C P(A) 0.8 0.2 P(CIB) 0.8 0.2 0.5 0.5 (C) A B D A +a +a -a ra B +b &&&& +b -b B +b -b +b -b D +d -d +d -d P(BIA) 0.8 0.2 0.5 0.5 P(DIB) 0.7 0.3 0.1 0.9