Graphical Models: Assignment 3
Due February 13, 2017
- If Josin Stalif (dictator of Depravia) has the goal of becoming a world
power, he may be planning to invade Impestuostria and he probably is
developing nuclear weapons. If he is developing nuclear weapons, he
may try to steal nuclear materials and will probably buy reactors from
first-world countries. If he is planning to invade Impestuostria,
Rechtian intelligence will probably see a troop buildup near the
demilitarized zone. A troop buildup could also occur as part of a
routine training exercise, but the message traffic received by Rechtian
intelligence would probably be different for exercise versus invasion.
- Develop a Bayesian network structure (nodes, arcs and states)
to infer Stalif's intentions. Use Bayesian network software to draw
- Explain your
network. Describe your nodes, states, and arcs, and explain why you
chose the structure you did.
- Enter local probability distributions for your Bayesian network. Explain your distributions.
- Consider two qualitatively different scenarios: (1) Rechtian
intelligence sees a troop buildup and message traffic looks like an
exercise; (2) Rechtian intelligence sees a troop buildup, message
traffic does not look like an exercise, and Stalif has initiated a
contract to buy a nuclear reactor from the country of Appesia. Compare
the prior probability that Stalif has the goal of becoming a world
power, and the posterior probabilities under the two different
- Consider a noisy-OR model with k causes C1, ..., Ck of an effect E. Assume that C1, ..., Ck are independent a priori. Show that conditional on E = 0 (the effect is false), the causes C1, ..., Ck remain independent.