COMP 4200: Expert Systems

1. COMP 4200: Expert Systems Dr. Christel Kemke Department of Computer Science University of Manitoba COMP 4200 - Example Autmotive Diagnosis

2. Example: Automotive Diagnosis COMP 4200 - Example Autmotive Diagnosis

3. Auto Diagnosis – Rule-Base Rule 1: if the engine is getting gas, and the engine will turn over, then the problem is spark plugs. Rule 2: if the engine does not turn over, and the lights do not come on, then the problem is battery or cables. Rule 3: if the engine does not turn over, and the lights do come on, then the problem is the starter motor. Rule 4:if there is gas in the fuel tank, and there is gas in the carburetor, then the engine is getting gas. COMP 4200 - Example Autmotive Diagnosis

4. Auto Diagnosis – Conceptualization Rule 1: if the engine is getting gas, engine-gets-gas and the engine will turn over, engine-turns then the problem is spark plugs. problem(spark-plugs) Rule 2: if the engine does not turn over, not(engine-turns) and the lights do not come on, not(lights-on) then the problem is battery or cables. problem(battery-or-cables) Rule 3: if the engine does not turn over, not(engine-turns) and the lights do come on, lights-on then the problem is the starter motor. problem(starter-motor) Rule 4:if there is gas in the fuel tank, gas-in-tank and there is gas in the carburetor, gas-in-carburetor then the engine is getting gas. engine-gets-gas COMP 4200 - Example Autmotive Diagnosis

5. Auto Diagnosis – Reasoning Tree Rule 1Rule 2 problem(spark-plugs) problem(battery-or-cables) andand engine-gets-gas engine-turns not(engine-turns)not(lights-on) Rule 3Rule 4 problem(starter-motor) engine-gets-gas andand not(engine-turns) lights-on gas-in-tank gas-in-carburetor. COMP 4200 - Example Autmotive Diagnosis

6. Auto Diagnosis – Reasoning Tree spark-plugs battery-or-cables starter-motor andand engine-gets-gas engine-turns lights-on and gas-in-tank gas-in-carburetor and not not not COMP 4200 - Example Autmotive Diagnosis

7. Auto Diagnosis - Simulation WorkingMemoryMatching Rules (goals, sub-goals) (backward reasoning) Rule 1 Rule 2 Rule 3 the problem is x Select and applyRule 1 Rule Tracking (for explanation) if the engine is getting gas and the engine will turn over thenthe problem is spark plugs Rule 1 COMP 4200 - Example Autmotive Diagnosis

8. Simulation 2 WorkingMemoryMatching Rules (goals, sub-goals) (backward reasoning) the engine is getting gas the engine will turn over the problem is spark-plugs ... Rule 4 Select and applyRule 4Rule Tracking if there is gas in the fuel tank, and there is gas in the carburetor, thenthe engine is getting gas. Rule 1 Rule 4 COMP 4200 - Example Autmotive Diagnosis

9. Simulation 3 WorkingMemoryMatching Rules (goals, sub-goals) (backward reasoning) there is gas in the fuel tank there is gas in the carburetor the engine is getting gas the engine will turn over the problem is spark-plugs no new applicable rules there is gas in the fuel tank there is gas in the carburetor the engine is getting gas the engine will turn over the problem is spark-plugs ground facts COMP 4200 - Example Autmotive Diagnosis

10. Auto Diagnosis – User Interaction there is gas in the fuel tank there is gas in the carburetor the engine is getting gas the engine will turn over the problem is spark-plugs System: Does the engine turn over? User: Yes, it does. System: Please check whether there is gas in the fuel tank. User: Why? System (justifies): Because if there is gas in the fuel tank and gas in the carburetor then the engine is getting gas(rule 4)andif the engine is getting gas and the engine turns over, then the problem are the spark plugs(rule 1). COMP 4200 - Example Autmotive Diagnosis