5/12/1999 Li-we Pan1 指導老師 ： 何正信教授 學生：潘立偉 學號： M 日期： 5/12/1999 Wolfgang Wilke, Barry Smyth, Pádraig Cunningham “Case-Based Reasoning Technology From Foundations to Applications”, Chap6 Mario Lenz, Bartsch -Spörl, Hans-Dieter Burkhard, Stefan Wess (Eds.), 1998 Using Configuration Technique for Adaptation

5/12/1999 Li-we Pan2 Continuum of design tasks Open ProblemsCreative DesignClosed Programs Routine Design Configuration Innovative Design Planning Program Design Problem Configuration is a design task that is the target of much AI search. It’s a comparatively tractable design task and thus can be completely automated in a knowledge based system (KBS). e.g. XCON

5/12/1999 Li-we Pan3 Configuration Given –The user requirements for a system –a set of predefined components –the knowledge of how components can be connected Goal : –find the sets of components fulfilling the user-requirements and respecting all the compatibility much use constraint satisfaction problem(CSP) Requirements Component Selection configuration Components Working Design Glue Components

5/12/1999 Li-we Pan4 Adaptation within configuration Substitutional Adaptation Compositional Adaptation Derivational Adaptation Transformational Adaptation Increasing Adaptation Complexity

5/12/1999 Li-we Pan5 The adaptation Framework A configuration-based approach to adaptation is only suitable when this mapping is well-behaved Simple action only define a function that determines a new value for the attribute Complex actions can additionally generate consecutive adaptation operators which are needed to complete the adaptation of the attributes the knowledge needed by the adaptation actions to evaluate the new value is provided by –rules : suggest preferences for the application –constraints : exclude illegal solutions as well as the application of not permitted operators or actions –functions : express well defined dependencies between different parameters of the problem and solution description and their implication on the solution, so they can be used to calculate new values for parameters

5/12/1999 Li-we Pan6 Mapping between description and solution space. Configuration Based Adaptation Description Space Solution Space Mapping Knowledge Correlating Descriptions Mapping knowledge is needed to express this relation by correlation groups of description features with groups of solution feature (in composition and transformational adaptation)

5/12/1999 Li-we Pan7 Complex Operator Complex Action Complex Operator Simple Operator Simple Action Subconcept Concept Attribute value Application of operator Control flow Information flow Modification of the solution is applied to Provides knowledge is applied to generates Modifies structure and values Modifies value top to down

5/12/1999 Li-we Pan8 The adaptation operator for simple attributes Calculate Evaluation function on solution attributes Modify Evaluation function on solution and case attribute Default Select default value consistent with constraints Copy Select value form retrieved cases Ask Prompt user for a value Adapt Parameter Adaptation Operator for simple attributes refined to Simple Adaptation Action new value of attribute

5/12/1999 Li-we Pan9 Adapt Concept Compose Select concept form retrieved cases Each parameter conflicting with constraints Decompose Create subconcepts of attribute Each sub- concept and parameter Specialize Select specialization of concept Specialized concept The adaptation operator for complex attributes Adaptation Operator for complex attributes refined to Complex Adaptation Actions new value of attribute generate adaptation operator for:

5/12/1999 Li-we Pan10 Adaptation Operator Use structuring adaptation knowledge the adaptation operators are scheduled on a working agenda executed adaptation operators are stored in an hierarchical history used for backtracking an adaptation operator contains slots to store information about what has already been tried to adapt the attribute which can be used for effective backtracking

5/12/1999 Li-we Pan11 Adaptation Operator for Action Adaptation operator for simple attributes –SAO=(attribute, old-value, actions, used-value, dependents) Adaptation operator for complex attributes –CAO=(attribute,old-value,actions,used- value,operator,dependents)

5/12/1999 Li-we Pan12 cont. –When backtracking determines that an operator has to be re-executed the old value of the attribute it restored using the old-value-slot –The next possible action can be determined by examining the already used ones stored in the actions-slot –The repeated use of values is prevented by excluding those stored in the used-values-slot –If the value of the attribute is changed during the re-execution of the operator, all operators referenced in the dependents-slot must be marked to be re-executed

5/12/1999 Li-we Pan13 Adaptation Actions SAA : a function which return a new value for an attribute, given the attribute, the current solution, the query, the retrieved cases and optionally a list of values which are not permitted as results. If an action is not applicable to an attribute, it return a nil-value CAA = (action, effects) –action : a simple adaptation action performed by this operator. The action describes the changes done to the solution when this operator is used –effects : a function which generates the necessary adaptation operators after the execution of action. It describes what has to be done to complete the adaptation of the concept the action is applied to

5/12/1999 Li-we Pan14 Algorithm of Adaptation Operator If an attribute is complex… –store current value of the complex attribute in the old-value-slot –select applicable complex action. Add it to the action-list –execute simple adaptation action of the chosen complex action and set attribute value. Add concept to the used-values-set –Generate the new adaptation operators. Store the result in the operators-set and add the returned operators to the agenda –If no executable operator could be found, trigger backtracking else (attribute is simple)… –Store current value of the simple attribute in the value-slot. –Evaluate actions until one returns an attribute value which satisfies the constraints –Add the action to the action-list and the new value to the used-values-list. Store the new value in the attribute. –If no value id consistent, trigger backtracking.

5/12/1999 Li-we Pan15 The Knowledge Needed for Adaptation Compose and Copy –there can be constraints which determine which case components can be chosen for constructing the solution –These constraints describe relations between the description attributes in the query and a case –there can be a special similarity measure, other than the one used for retrieval, to determine the most appropriate component from the set of those that fulfill the constraints

5/12/1999 Li-we Pan16 Cont. Specialize –choose a specialization dependent of values of concepts stored in other attributes Decompose –associated to the component decomposed instead of the one specialized Calculate and Modify –the knowledge consists mainly of the function which calculates the new value