Presentation on theme: "Lecture 5: Reuse, Adaptation and Retention"— Presentation transcript:
1 Lecture 5: Reuse, Adaptation and Retention Case Based ReasoningLecture 5: Reuse, Adaptation and Retention
2 Outline Re-use Adaptation Retention How to re-use retrieved solutions Why might we want to revise the solution?Types of adaptationRetentionWhy might we wish to retain cases?
3 Re-Using Retrieved Solutions Single retrieved solutionRe-use this solutionMultiple retrieved solutionsVote/average of retrieved solutionsWeighted according toRankingSimilarityIterative retrievalSolve components of the solution one at a time
4 Multiple Retrievals Whole solution generated in single retrieval Single components generated in each retrievalParallelIncremental?Subproblem?Subproblem?Problem?SubproblemSuggestedPart SolutionSuggestedPart SolutionSuggestedSolutionSuggestedSolution
5 When is Adaptation Needed? ClassificationAll solutions likely to be represented in case-baseAdaptation corrects for lack of casesConstructive problem solvingAll “designs” unlikely to be represented in case-baseRetrieved cases suggest initial “design”Adaptation alters the “design” to reflect novel feature valuesRedesign of Gas-taps(Copreci, Spain)
6 Assumptions for Adaptation Similar problems have similar solutionsThe effort required to adapt a retrieved solution will be less the more similar it is to the required solution
7 How to Adapt the Solution Adaptation alters proposed solutiontakes account of differences between new and retrieved problemsNull adaptation - copy retrieved solutionUsed by CBR-Lite systemsManual or interactive adaptationUser adapts the retrieved solution (Adapting is easier than solving?)Automated adaptationCBR system is able to adapt the retrieved solutionAdaptation knowledge required
8 Automated Adaptation Methods Substitutionchange some part(s) of the retrieved solutionsimplest and most common form of adaptationTransformationalters the structure of the solutionGenerativereplays the method of deriving the retrieved solution on the new problemmethod of solution is part of retrieved casemost complex form of adaptation
9 Examples of Adaptation CHEFCBR system to plan Szechuan recipesHammond (1990)Substitution adaptationsubstitute ingredients in the retrieved recipe to match the menuRetrieved recipe contains beef and broccoliNew menu requires chicken and snowpeasReplace chicken for beef, snowpeas for broccoliTransformation adaptationAdd, change or remove steps in the recipeSkinning step added for chicken, not done for beef
10 Examples of Adaptation Car diagnosis exampleSymptoms, faults and repairs for brake lights are analogous to those for headlightSubstitution: brake light fusePlanning exampleTrain journeys and flights are analogousTransformation: flights need check-in step added
11 Adaptation in CBR-Works Provides adaptation rulesIF a THEN bclassic production rulesExampleAdd £1000 to the price of a new car for a different colour
13 Adaptation in CBR-Works: Example Retrieval without adaptation
14 Adaptation in CBR-Works: Example Retrieval + adaptationPredicting value of the price attribute
15 Adaptation in CBR-Works: Example Adaptation rule to predict the value of Price
16 Other Rules in CBR-Works CBR-Works also uses completion rules tocalculate a dependent attribute valueset default valuealter the feature weights in certain circumstancesUsed tocomplete a queryfill-in missing data during case creationalter similarity calculations for retrieval
17 Adaptation in ReCallBy default, ReCall uses the vote mechanism of k-NN to predict a value for the target attribute.E.g., the predicted value of the query (shown here in black) will be grey according to a 3-NN algorithm which retrieves 3 similar cases (2 in grey and 1 in beige)
18 Adaptation in ReCallAlternatively, ReCall allows you to write adaptation rules to predict a value for your query based on a single (most similar) case.You can use ReCall’s own language, or use the more powerful and widely used language Tcl.To find out more: refer to ReCall’s Lab notes.
19 Two Schools of Thought in CBR Adaptation is the most contentious issue in CBROne group believes adaptation is not importantThe problem cannot be solved using CBRA CBR system without adaptation capabilities is called CBR Retrieval SystemOthers believe it is vitalWithout adaptation and generation of new solutions there is no reasoning in CBRA CBR system with adaptation capabilities is called fully-fledged CBR system
20 Retention What can be learned Forgetting cases New experience to be retained as new caseRepresenting the new caseContents of new caseIndexing of new caseForgetting casesFor efficiency or because out of dateDeleting an old caseOld is not necessarily badDoes it leave a gap?
21 Example Do we need to retain the new case? outlookYessunnycloudyrainyhumidityNohighnormalwindytruefalseOutlook=Cloudy Temp.=Cool Humidity=High Windy=False Play= YesOutlook=Cloudy Temp.=Mild Humidity=High Windy=False Play= NoDo we need to retain the new case?Do we need to rebuild the decision tree index?
22 Summary Reuse Revise Retain Initial solution from retrieved cases Adapt initial solution to reflect differences between new and retrieved problemsCBR-Works adaptation rulesRetainWhen to retain and whether to replaceRepresentation and indexing
23 Reading Research Papers S. Craw, J. Jarmulak & R. Rowe. Learning and Applying Case-Based Adaptation Knowledge. Proceedings 4th ICCBR Conference, p ,B. Smyth & M. T. Keane. Adaptation-Guided Retrieval: Questioning the similarity assumption. Artificial Intelligence 102: ,