ARTIFICIAL INTELLIGENCE[INTELLIGENT AGENTS PARADIGM]

Professor Janis Grundspenkis

Riga Technical University

Faculty of Computer Science and Information Technology

Institute of Applied Computer Systems

Department of Systems Theory and Design

E-mail: Janis.Grundspenkis@rtu.lv

EXPERT SYSTEMS BASEDON FIRST-ORDER LOGIC

Expert Systems Basedon First-order Logic

EXPERT SYSTEM’S ARCHITECTURE

Inference EngineInferenceProcedure

UserInterface

Knowledge Base (KB)Formally described

knowledge

Working MemoryFacts

Expert Systems Basedon First-order Logic

EXPERT SYSTEM’S ARCHITECTURE (continued)

An inference procedure I can be described by the sentences that it can derive.

KB |= I means that the sentence is derived from KB by I.

Expert Systems Basedon First-order Logic

MODUS PONENSProblem’s description1. Anyone who is lucky wins the lottery.2. Anyone who wins the lottery is happy.3. At least one who is happy studies at the

university.4. Anyone who studies at the university can

pass all his examsinations.5. Anyone who pass all his examination

graduates from the university.

Expert Systems Basedon First-order Logic

MODUS PONENS (continued)Logical Sentences1. X(lucky(X) win(X, lottery))2. X(win(X, lottery) happy(X))3. X(happy(X) study(X))4. XY(study(X) pass(X, Y))5. XY(pass(X, Y) graduate(X))

Expert Systems Basedon First-order Logic

MODUS PONENS (continued)Facts6. George is lucky.

lucky(george)7. George passed his Mathematical Logic

and Artificial Intelligence (ML&AI) examination.pass(george, ml&ai)

Expert Systems Basedon First-order Logic

MODUS PONENS (continued)

S1: lucky(X) win(X, lottery)S2: win(X, lottery) happy(X)S3: X(happy(X) study(X))S4: study(X) pass(X, Y)S5: pass(X, Y) graduate(X)

UserInterface

InferenceEngineModusPonens

Working Memory

KB

Expert Systems Basedon First-order Logic

MODUS PONENS (continued)

S1S2S3S4S5

UserInterface Inference

EngineModusPonens

Working Memory

KB

Q: Is George lucky?A: Yes

Expert Systems Basedon First-order Logic

MODUS PONENS (continued)KB Inference Engine

Modus PonensS1S2S3S4S5

F1: lucky(george)

UserInterface

Working Memory

KB Inference EngineModus Ponens

Expert Systems Basedon First-order Logic

MODUS PONENS (continued)

S1S2S3S4S5

S1: lucky(X)win(X, lottery)F1: lucky(george)Unification{ george/X }

UserInterface

KB Inference EngineModus Ponens

Working Memory

F1: lucky(george)

S1S2S3S4S5

F1: lucky(george)F2: win(george, lottery)

Expert Systems Basedon First-order Logic

MODUS PONENS (continued)

UserInterface

KB Inference EngineModus Ponens

Working Memory

S1S2S3S4S5

S2: win(X, lottery) happy(X)F2: win(george, lottery)Unification{ george/X }

F1: lucky(george)F2: win(george, lottery)

Expert Systems Basedon First-order Logic

MODUS PONENS (continued)

UserInterface

KB Inference EngineModus Ponens

Working Memory

S1S2S3S4S5

F1: lucky(george)F2: win(george, lottery)F3: happy(george)

Expert Systems Basedon First-order Logic

MODUS PONENS (continued)

UserInterface

KB Inference EngineModus Ponens

Working Memory

S1S2S3S4S5

S3: X(happy(X) study(X)F3: happy(george)Unification{ george/X }After dropping XS3: happy(george) study(george)

F1: lucky(george)F2: win(george, lottery)F3: happy(george)

Expert Systems Basedon First-order Logic

MODUS PONENS (continued)

UserInterface

KB Inference EngineModus Ponens

Working Memory

S1S2S3S4S5

F1: lucky(george)F2: win(george, lottery)F3: happy(george)F4: study(george)

Expert Systems Basedon First-order Logic

MODUS PONENS (continued)

UserInterface

KB Inference EngineModus Ponens

Working Memory

S1S2S3S4S5

S4: study(X) pass(X, Y)F4: study(george)Unification{ george/X }Unification for Y?There is not any knowledge about that

F1: lucky(george)F2: win(george, lottery)F3: happy(george)F4: study(george)

Expert Systems Basedon First-order Logic

MODUS PONENS (continued)

UserInterface

KB Inference EngineModus Ponens

Working Memory

S1S2S3S4S5

S4: study(X) pass(X, Y)F4: study(george)Unification{ george/X }Unification for Y?

F1: lucky(george)F2: win(george, lottery)F3: happy(george)F4: study(george)

Expert Systems Basedon First-order Logic

MODUS PONENS (continued)User

InterfaceKB Inference Engine

Modus Ponens

Working Memory

Q: Did George pass all his exams?A: Yes, George passed his Mathematical Logic and Artificial Intelligence exam

S1S2S3S4S5

S4: study(X) pass(X, Y)F4: study(george)Unifications{ george/X }Unification for Y?

F1: lucky(george)F2: win(george, lottery)F3: happy(george)F4: study(george)F5: pass(george, ml&ai)

Expert Systems Basedon First-order Logic

MODUS PONENS (continued)

UserInterface

KB Inference EngineModus Ponens

Working Memory

S1S2S3S4S5

S4: study(X) pass(X, Y)F4: study(george)Unifications{ george/X }{ ml&ai/Y }

F1: lucky(george)F2: win(george, lottery)F3: happy(george)F4: study(george)F5: pass(george, ml&ai)

Expert Systems Basedon First-order Logic

MODUS PONENS (continued)

UserInterface

KB Inference EngineModus Ponens

Working Memory

S1S2S3S4S5

S5: pass(X, Y) graduate(X)F5: pass(george, ml&ai)Unifications{ george/X }{ ml&ai/Y }

F1: lucky(george)F2: win(george, lottery)F3: happy(george)F4: study(george)F5: pass(george, ml&ai)

Expert Systems Basedon First-order Logic

MODUS PONENS (continued)

UserInterface

KB Inference EngineModus Ponens

Working Memory

S1S2S3S4S5

F1: lucky(george)F2: win(george, lottery)F3: happy(george)F4: study(george)F5: pass(george, ml&ai)F6: graduate(george)

Expert Systems Basedon First-order Logic

MODUS PONENS (continued)

UserInterface

KB Inference EngineModus Ponens

Working Memory

Conclusion:George graduatesfrom the university

S1S2S3S4S5

F1 F4F2 F5F3 F6

Expert Systems Basedon First-order Logic

MODUS PONENS (continued)

UserInterface

KB

Inference EngineModus Ponens

Working Memory