CECS 451
Assignment 9
Total: 44 Points
General Instruction
• Submit unzipped files in the Dropbox folder via BeachBoard (Not email or in class).
1. Consider Figure 1, and implement a program to answer the query P~ (C|¬s, w) by using
MCMC sampling. The program should generate 1, 000, 000 samples to estimate the
probability. To answer (a) and (b), you can prepare the answers with scratch paper and
print-out them. However, you have to implement a simulation program to answer (c).
(a) (8 points) Show P~ (C|¬s, r), P~ (C|¬s, ¬r), P~ (R|c, ¬s, w), P~ (R|¬c, ¬s, w).
(b) (16 points) Show the transition probability matrix Q ∈ R
4×4 where
qij = transition probability from Si to Sj
in Figure 2.
(c) (20 points) Show the probability of the query P~ (C|¬s, w)
(d) Please follow the output format. (Fix precisions using "0:.nf".format)
Part A. The sampling probabilities
P(C|-s,r) = <..., ...>
P(C|-s,-r) = <..., ...>
P(R|c,-s,w) = <..., ...>
P(R|-c,-s,w) = <..., ...>
Part B. The transition probability matrix
S1 S2 S3 S4
S1 . . . .
S2 . . . .
S3 . . . .
S4 . . . .
Part C. The probability for the query
P(C|-s,w) = <..., ...>
CECS 451 Assignment 9 - Page 2 of 2
Figure 1: A multiply connected network with conditional probability tables. Note that the
probabilities are slightly different than the lecture notes and the text book example.
Figure 2: Possible states diagram
