Fall 2007 COMP Example Autmotive Diagnosis 1 COMP 4200: Expert Systems Dr. Christel Kemke Department of Computer Science University of Manitoba

Fall 2007 COMP Example Autmotive Diagnosis 2 Example: Automotive Diagnosis

Fall 2007 COMP 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.

Fall 2007 COMP 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

Fall 2007 COMP Example Autmotive Diagnosis 5 Auto Diagnosis – Reasoning Tree Rule 1 Rule 2 problem(spark-plugs)problem(battery-or-cables) and engine-gets-gas engine-turnsnot(engine-turns) not ( lights-on) Rule 3Rule 4 problem(starter-motor) engine-gets-gas and not(engine-turns) lights-ongas-in-tank gas-in-carburetor.

Fall 2007 COMP Example Autmotive Diagnosis 6 spark-plugsbattery-or-cables starter-motor and and engine-gets-gas engine-turnslights-on and gas-in-tank gas-in-carburetor Auto Diagnosis – Reasoning Tree not and not

Fall 2007 COMP Example Autmotive Diagnosis 7 Auto Diagnosis - Simulation Working Memory Matching Rules (goals, sub-goals)(backward reasoning) the problem is x Rule 1 Rule 2 Rule 3 Select and apply Rule 1 Rule Tracking (for explanation) if the engine is getting gas and the engine will turn over then the problem is spark plugs Rule 1

Fall 2007 COMP Example Autmotive Diagnosis 8 Simulation 2 Working Memory Matching Rules (goals, sub-goals)(backward reasoning) the engine is getting gas the engine will turn over the problem is spark-plugs Select and apply Rule 4 Rule Tracking if there is gas in the fuel tank, and there is gas in the carburetor, then the engine is getting gas. Rule 1 Rule 4... Rule 4

Fall 2007 COMP Example Autmotive Diagnosis 9 Simulation 3 Working Memory Matching 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

Fall 2007 COMP Example Autmotive Diagnosis 10 Auto Diagnosis – User Interaction 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) and if the engine is getting gas and the engine turns over, then the problem are the spark plugs (rule 1). 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