基于决策树与影响图石油勘探决策分析.pdfVIP

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DecisionTreeforOilWildcatter

Classicalwaytorepresentdecisionproblemswithmultipledecisions

Explicitlyshowallpossiblesequencesofdecisionsandobservations.

Example:OilWildcatter

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SolvingDecisionTrees

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SolvingDecisionTrees

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InfluenceDiagram

ADAGwiththreetypesofnodes

Chancenodes,decisionnodes,andutilitynodes

Thereisadirectedpathcontainingallthedecisionnodes.

Theutilitynodeshavenochildren.

Eachchancenodeisassociatedwiththeconditionaldistributiongiven

itsparents.

Eachutilitynodeisassociatedwithautilityfunction,areal-valued

functionofitsparents.

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InfluenceDiagram

Aninfluencediagramfortheoilwildcatterproblem

Decision:T:test{y,n};D:drill={y,n}

Utility:C:costoftest;V:Benefitofdrilling

Chance:

➢O:Oil={dry,wet,soaking}

➢R:seistructure

{no-structure,open-structure,closed-structure,no-result}

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FindingOptimal

Firstidea:

Converttodecisiontreeandsolveit

Exponentialstill!

Next:

VariableEliminationAlgorithmforsolvinginfluencediagrams

Note

BNinference:Allorderingsgivecorrectresult,butmighthave

differentcomplexity

ID:Mustuse“strongeliminationorderings”.