Case-based Reasoning

What is CBR?Case-based reasoning is a problem solving

paradigm. CBR also is an approach to incremental,

sustained learning.When a problem is successfully solvedWhen an attempt to solve a problem fails as

well.

Introduction

Central tasks of all case-based reasoning models1. Identify the current problem situation. 2. Find a past case similar to the new one. 3. Use that case to suggest a solution to the

current problem. 4. Evaluate the proposed solution, and update

the system by learning from this experience.

Deciding what to store in a case. Finding an appropriate structure.Deciding how the case memory should be

organized .How to integrate the case memory structure into

a model of general domain knowledge.

1. Representation  of  Cases

The Dynamic Memory Model

The Category & Exemplar Model

Identify Feature Initially  Match Select

2. Case Retrieval

CopyAdapt

Transformational reuse Derivational reuse

3. Case Reuse

Evaluate solutionRepair fault

4. Case Revision

Extract Index Integrate

5.Case Retainment  Learning

Case-based planning is the reuse of past successful plans in order to solve new planning problems.

Case-based planning

Extracting behavioral knowledge from an expert in form of individual cases. This knowledge can be reused to achieve the specific open goals in the current plan.

Allows the AI engine to create and adapt plans in an efficient and effective manner while performing the task.

On-line Case-based Plan Adaptation

Darmok was designed to play the game of WARGUS and apply the plan adaptation techniques.

Darmok learns behaviors from expert demonstrations, and then uses case-based planning to play the game reusing the learnt behaviors.

Case-Based Planning in WARGUSDarmok system

Darmok system

A behavior has two main parts:The declarative partThe procedural part

The state of a behavior Goal

Plan Representation Language

Run-Time Plan Expansion and Execution

Plan Dependency Graph GenerationPrecondition-success condition matcher (ps-

matcher).Removal of unnecessary actionsAdaptation for unsatisfied preconditions

On-Line Case-Based Plan Adaptation

Taking the success conditions of the root of the plan.

Finding out which actions in the plan contribute to the achievement of these success conditions.

These actions are called direct sub-plans for the sub-goal.

4- All direct sub-plans are added to the plan dependency graph. Then the plan dependency graph generator analyzes the preconditions of each of these direct sub-plans.

Plan Dependency Graph