Sommario
TRUTH MAINTENANCE SYSTEMS (TMS)
Monotonic Reasoning Systems
An Example
Nonmonotonic Reasoning Systems
Main Functions of TMS (o Belief Revision) Systems
Main Problems of a TMS
Justification-Based TMS (JTMS, Doyle-1979)
General Architecture of a KBS including a JTMS
PS-JTMS Interface
Main Functionality of JTMS
Labelling
New Justifications for a Node
The Example of Pluto
Nonmonotonic Justification
Representing Justifications with Support Lists
Premises
Monotonic Justifications
Support List for the Assumptions
An Example of Default Reasoning
An Example of Use of the JTMS
Cont.d
Representation of Nodes
An Example
Justification (or Dependency) Network
Operation of JTMS
Providing New Justifications
Retracting a (Nonmonotonic) Justification
Circularity
Activation of the Truth Maintenance Procedure
Truth-Maintenance Procedure
Procedure for Retracting Assumptions
DDB (Simplified Version)
Can DDB Be Replaced by Chronological Backtracking?
Drawbacks of Chronological Backtracking
Evaluation of JTMS
Other Truth Maintenance Systems
Assumption-Based TMS (ATMS, DeKleer-1986)
Hypothetical Reasoning
Main Features of the ATMS
Nodes
Assumptions and Justifications
The Term 'Assumption'
The Term 'Justification'
Environments
Nogoods
Environment Lattice
cont.d
Contexts
Labels
cont.d
Goals of the ATMS
Example
Types of nodes in the ATMS
Representation of Nodes
Premises
Assumptions
Assumed Nodes
Derived Nodes
ATMS Operation
Complexity of the ATMS
Evaluation of ATMS
ATMS vs. JTMS
Other TMS
When are TMS Systems Useful?
Applications Areas of TMS Systems
User Modeling
Student Modeling
Data Interpretation
EXAMPLES
Forbus' example
The Dependency Network
Inconsistency of a and b
JTMS-ATMS Comparison
An Initial Dependency Network
The JTMS Case
Inconsistency of d2 and d7
Dealing with Inconsistencies within JTMS: DDB
The ATMS Case
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