Rule-based Systems Brian C. Williams 16.410-16413 September 10th, 2003 from: 6.034 Tomas Lozano perez Rule Based Systems Big idea: Separation of Knowledge and Control Rules Forward Rule Systems Goal-directed Rule Systems
1 Rule-based Systems 1 Brian C. Williams 16.410 – 16.413 September 10th, 2003 Slides adapted from: 6.034 Tomas Lozano Perez Rule Based Systems • Big idea: Separation of Knowledge and Control • Rules • Forward Rule Systems • Goal-directed Rule Systems
Rules on NEAr and messenger A Simple Reflex System Reflex Rules NEAR CourtesyofNasa/JhuaPl.http://www.jhuapl.com Applying Rules to the NeAr Spacecraft Sample NEAR rule ymptom (Charger current>0.8 A) Switch to the redundant charger and disengage the CourtesyofNasa/JhuaPl.http://www.jhuapl.con
2 Reflex Rules NEAR Spacecraft Observations Action Rules on NEAR and Messenger: A Simple Reflex System Applying Rules to the NEAR Spacecraft • Sample NEAR rule • Symptom : – (Charger current > 0.8 A) for 10 sec • Recovery : – Switch to the redundant charger and disengage the primary. Courtesy of NASA/JHUAPL. http://www.jhuapl.com Courtesy of NASA/JHUAPL. http://www.jhuapl.com
Rules on Cassini: A State Centered Approach Rules Observations CourtesyofNasa/jPl-cAlteCh.http://www.jpl.nasa.gov Rules Deduction style IF Antecedent THEN B2 Consequent Each rule should capture a single independent inference and should make sense by itself Examyf (is-a-parent-of ?x 2y/variables is-a- parent-o￡?y? ThEN (is-a-grand-parent-of ?x ?z) Variables of the same name must have the same value
3 Rules on Cassini: A State Centered Approach Diagnostic Rules Repair Rules Failure Mode Cassini Spacecraft Observations Action • Each rule should capture a single independent inference and should make sense by itself • Deduction style Rules IF A1 A2 THEN B1 B2 Antecedent Consequent variables •Variables of the same name must have the same value •Example: IF (is-a-parent-of ?x ?y) (is-a-parent-of ?y ?z) THEN (is-a-grand-parent-of ?x ?z) Courtesy of NASA/JPL-Caltech. http://www.jpl.nasa.gov
Rule Based systems Big idea: Separation of Knowledge and Control Rules Forward Rule Systems rward chaining Production rules Goal-directed Rule Systems Rule based architecture Programs: Knowledge is lost within the control structures .Rule-based Architectures: Separate knowledge and control Knowledge: rules assertions
4 Rule Based Systems • Big idea: Separation of Knowledge and Control • Rules • Forward Rule Systems • Forward chaining • Production rules • Goal-directed Rule Systems Rule Based Architecture Assertions Rules • Programs: Knowledge is lost within the control structures •Rule-based Architectures: Separate knowledge and control • Knowledge: rules & assertions
Rule based architecture Rule sse Interpreter Programs: Knowledge is lost within the control structures ule- based Architectures: Separate knowledge and control Knowledge assertions Control: rule interpreter Rule based architecture Rule interpreter Programs: Knowledge is lost within the control structures .Rule- based Architectures: Separate knowledge and control Knowledge: rules& assertions Control: rule interpreter
5 Rule Based Architecture Assertions Rules Rule Interpreter • Programs: Knowledge is lost within the control structures •Rule-based Architectures: Separate knowledge and control • Knowledge: rules & assertions • Control: rule interpreter Rule Based Architecture Assertions Rules Rule Interpreter Pick rule • Programs: Knowledge is lost within the control structures •Rule-based Architectures: Separate knowledge and control • Knowledge: rules & assertions • Control: rule interpreter