Daphne Koller Decision Making Maximum Expected Utility Probabilistic Graphical Models Acting
Dec 30, 2015
Daphne Koller
Simple Decision MakingA simple decision making situation D:• A set of possible actions Val(A)={a1,
…,aK}• A set of states Val(X) = {x1,…,xN}• A distribution P(X | A)• A utility function U(X, A)
Daphne Koller
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Decision rule at action node A is a CPD: P(A | Parents(A))
Daphne Koller
Expected Utility with Information
• Want to choose the decision rule A that maximizes the expected utility
Daphne Koller
Survey
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Finding MEU Decision Rules
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Daphne Koller
MEU Algorithm Summary• To compute MEU & optimize decision at A:– Treat A as random variable with arbitrary CPD– Introduce utility factor with scope PaU
– Eliminate all variables except A, Z (A’s parents) to produce factor (A, Z)
– For each z, set:
Daphne Koller
Decision Making under Uncertainty
• MEU principle provides rigorous foundation• PGMs provide structured representation for
probabilities, actions, and utilities• PGM inference methods (VE) can be used for
– Finding the optimal strategy– Determining overall value of the decision situation
• Efficient methods also exist for:– Multiple utility components– Multiple decisions