1. A I (Artificial Intelligence)
Professor I. J. Chung

2. AI (Artificial Intelligence)
Study of mental thinking & facilities with appropriate computational models
Solve the real world problems (see below).
Fundamental assumption of AI :
What the brain of human beings may be thought of at some level as a kind of computations.
Another definition of AI
One of major fields of computer science that makes it possible to perceive, think, reason and act.
(cognitive science, psychology)
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3. AI (Artificial Intelligence)
Emphasis an computation, reasoning, action, etc.
Task domain of AI
– mundane tasks
Perception : vision, speech
Natural language processing
: understanding, generation, translations, semantic modeling
Common sense reasoning
Robot control
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4. AI (Artificial Intelligence)
Formal tasks
Automated reasoning with formal logic
Game : chess, go, tic-tac-toe, etc.
Mathematics
geometry, logic, calculus, proving properties of programs
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5. AI (Artificial Intelligence)
Expert tasks
Engineering :
design, fault findings, manufacturing, planning
Scientific analysis :
Medical diagnosis & analysis
Financial analysis & planning
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6. AI (Artificial Intelligence)
Machine learning
symbol-based
: ID3 (decision tree), inductive bias, COBWEB,
explanation-based learning
Connectionist
: artificial neural networks
Social based
: genetic algorithm (Darwinism with competition)
Emergent : agent
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7. AI (Artificial Intelligence)
Eg. Analogy problems
A B C
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8. AI (Artificial Intelligence)
AI language
LISP ( functional declarative language )
Prolog ( logic declarative language )
LISP
Flexible language for symbolic manipulation rather than numeric computations
Functional programming language based on
λ - expression (McCarthy, of MIT 1965)
Interpreted language as opposed to compiled language
Widely used in ES/KBS, reasoning & learning, NLP, etc.
cf: Prolog (logic programming lang.)
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9. AI (Artificial Intelligence)
Basic Lisp Primitives
Atom : fundamental objects in LISP without parenthesis
E.g. OK I
List : collection of atom enclosed by parenthesis (nesting is allowed)
(I AM A BOY) (I (LOVE) YOU) (1.5)
Operator : arguments with lists (prefix notation)
( ) (* )
(/ ( ) (* ))
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10. AI (Artificial Intelligence)
Basic Lisp Primitives (cont.)
Procedure : basic program unit in LISP
Primitive : procedure supplied by LISP itself
Program : collection of procedures to solve a particular job
expression
integer
symbol
number
list
atom
real
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11. AI (Artificial Intelligence)
CAR & CDR
(CAR ’(I AM A BOY)) I
(CAR ’((I) AM A BOY))
(I)
(CAR ’((A B) C))
(A B)
(CDR ’(I AM A BOY))
(AM A BOY)
(CDR ’((I) AM A BOY))
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12. AI (Artificial Intelligence)
CAR & CDR (cont.)
(CDR ’((A B) C))
(C)
(CDR ’(I))
( )
(CADR ’(A B C)) ≡ (CAR (CDR ‘(A B C)))
(SETQ L ’(A B)) ; assignment statement in LISP with
L side- effects
(A B)
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13. AI (Artificial Intelligence)
APPEND : strings together the elements of all lists supplied as arguments
(SETQ L ’(A B))
(A B)
(APPEND L L)
(A B A B)
(APPEND L L L)
(A B A B A B)
(APPEND ’(A) ’( ) ’(B) ’( ))
(APPEND ’((A) (B)) ’((C) (D)))
((A) (B) (C) (D))
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14. AI (Artificial Intelligence)
LIST : makes a list out of a its arguments.
Each argument becomes an elements of the new list
(SETQ L ’(A B))
(LIST L L)
((A B) (A B))
(LIST L L L)
((A B) (A B) (A B))
(LIST ’L L)
(L (A B))
(LIST ’((A) (B)) ’((C) (D)))
(((A) (B)) ((C) (D)))
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15. AI (Artificial Intelligence)
CONS : takes a list and insert a new first element.
CONS is a mnemonic for list constructor.
(CONS <new first element> <some list>)
(CONS ’A ’(B C))
(A B C)
(CAR (CONS ’A ’(B C))) A
(CDR (CONS ’A ’(B C)))
(B C)
Note : assume that L is a list.
Then, (CONS (CAR L) (CDR L)) ≡ L
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16. AI (Artificial Intelligence)
(APPEND ’(A B) ’(C D))
(A B C D)
(LIST ’(A B) ’(C D))
((A B) (C D))
(CONS ’(A B) ’(C D))
((A B) C D)
(SETQ L ’(A B))
(LIST L L)
((A B) (A B))
(CONS L L)
((A B) A B)
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17. AI (Artificial Intelligence)
(APPEND L L)
(A B A B)
(LIST ’L L)
(L (A B))
(APPEND ’L L)
ERROR
(CONS ’L L)
(L A B)
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18. AI (Artificial Intelligence)
LENGTH, REVERSE, SUBST, LAST
LENGTH : number of top-level elements in a list
e.g
(LENGTH ’(A B)) 2
(LENGTH ’((A B) (C D)))
(SETQ L ’(A B))
(LENGTH L)
(LENGTH (APPEND L L)) 4
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19. AI (Artificial Intelligence)
LENGTH, REVERSE, SUBST, LAST
REVERSE : turns the top level of a list around
e.g
(REVERSE ’(A B))
(B A)
(REVERSE ’((A B) (C D)))
((C D) (A B))
(REVERSE L)
(REVERSE (APPEND L L))
(B A B A)
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20. AI (Artificial Intelligence)
LENGTH, REVERSE, SUBST, LAST
SUBST : takes 3 arguments, the last of which is an expression in which occurrences of a specified atom are to be replaced.
The first argument is the new expression to be plugged-in; the second argument is the atom to be replaced.
(SUBST <new exp> <old atom> <exp to substitute in>)
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21. AI (Artificial Intelligence)
e.g
(SUBST ’A ’B ’(A B C))
(A A C)
(SUBST ’B ’A ’(A B C))
(B B C)
(SUBST ’A ’X (SUBST ’B ’Y ’(SQRT (+ (* X X) (* Y Y)))))
(SQRT (+ (* A A) (* B B)))
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22. AI (Artificial Intelligence)
LENGTH, REVERSE, SUBST, LAST
LAST : returns a list that contains only the last element of the list as the argument.
e.g
(LAST ’ (A B C))
(C)
(LAST ’((A B) (C D)))
((C D))
(LAST ’A)
Error
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23. AI (Artificial Intelligence)
Procedure abstraction is done by using DEFUN to combine ingredients.
(DEFUN <procedure - name> (<para-1> <para-2> … <para-n>) <procedure-body>)
e.g
(DEFUN F_TO_C (TEMP) (/ (- TEMP 32) 1.8))
(F-TO-C 32)
(DEFUN EXCHANGE (PAIR)
(LIST (CADR PAIR) (CAR PAIR))))
(EXCHANGE ’(ADAM EVE))
(EVE ADAM)
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