Computer Science

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Artificial Intelligence
Computer Science Engineering Shiraz University
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• What is AI ?
• Making computers to act Intelligently
• What is Intelligence ? (Russell and Norvig
  1995)?
• Thinking like humans
• Acting like humans
• Thinking rationally
• Acting rationally

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• What are factors of Intelligence ?
• Understanding
• Reasoning
• Problem Solving
• Learning
• Common Sense
• Generalizing
• Inference
• Analogy
• Recall
• Intuition
• Emotion
• Self-awareness

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The Turing Test

• Proposed by Alan Turing in 1950 to provide a
  definition of intelligent behaviour.
• The computer is interrogated by a human via a
  teletype
• it passes the test if the interrogator cannot
  identify the answerer was computer or human

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The Turing Test Requirements

• Natural language processing
• Communicating with human understanding
  sentences
• Knowledge representation
• Storing facts and information
• Automated reasoning
• Concluding new facts using from existing facts
• Machine learning
• Using experiences
• Acting rationally in new situations
• Recognizing patterns

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The Total Turing Test

• adding to the agent a video interface and an
  acting arm
• it necessitates
• 1- Machine Vision
• 2- Robotics

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• Some examples of AI related topics
• Playing Chess with human
• Solving a Geometric Problem
• Selecting fastest way to destination
• Vision
• Traffic Controlling
• Automatic Conversation
• Pattern recognition
• Robot Controlling
• Deriving Proof of Mathematical theorems
• Symbolic Calculation
• Weather forecasting
• Disease diagnosis
• Symbolic
• erentiation and integration from mathematical
  expressions

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• Foundations of AI
• Philosophy (Dualism vs. Materialism)?
• Mathematics (Computation, Logic, Probability)?
• Linguistics (Understanding and Analysis of
  Languages)?
• Computer Science (provides and tools
  programmability, speed,
• storage, actions)?
• Psychology (The brain processes, study of human
  Behaviors)?
• Cognitive Sciences
• Neurology/Biology
• Engineering
• ...

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Some Examples
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Problem Solving using Search

• Searching Testing all possible states to find an
  appropriate solution.
• In many cases Search problems have a close
  relation with Trees

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Game Playing

• We can design game playing programs using search
  methods
• So, we should visit all possible states which can
  occur in a game.
• But like many search problems, there are methods
  to reduce the search states (eliminates some
  states having no effect on search solutions)

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Some other examples
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• Find maximum of the functions
• f(x) x e(1-x2) - ex log x
• f(x, y) x(log y y) y(x2 1)?
• f(x1, x2, x3, ... , x100) ...

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• If age of Ali is 3 times greater than age of his
  brother plus 1, and age of his brother is ¼ of
  age of Ali then find age of Ali and his brother.
• Can ordinary search methods be used to solve the
  above problem?
• Reasonable steps to solve the problem
• Getting and storing the text
• Analyzing text and extracting necessary
  information.
• Converting the information to suitable
  mathematical form
• Solving the equations and finding unknown
  variables

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• Write a program to simplify simple expressions

gtgtgt def simplify(expr) gtgtgt simplify((a b)
(a b))? a2 b2 gtgtgt simplify((a-b) (ab)
(a2 b2) a4 b4)? 2 a4 gtgtgt
simplify((a b)2 (a - b)2)? 4 a b
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• Write a program to differentiate simple
  mathematical expressions

gtgtgt def diff(expr, resp) gtgtgt diff(2 x2 x
4 , x)? 4 x - 1 gtgtgt diff((x - a)2 ,
x)? 2 x 2 a gtgtgt diff(y sin (y2),
y)? sin (y2) 2 y2 cos(y2)
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• Write a program to calculate integration

gtgtgt def integrate(expr, resp) gtgtgt
integrate(6 x 4 , x)? 3 x2 4 x
C gtgtgt integrate(x sin x , x)? 0.5 x2 -
cos x C gtgtgt integrate(y sin (y2), y)? -
0.5 cos (y2) C gtgtgt integrate(x sin x,
x)? - x cos x sin x C
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• Stages to solve such problems
• Assume we are going to simplify (x-y) (xy)

1- Transform the expression in the form dealing
with which is more convinient For example in
this case we can convert it to x, y,
-, x, y, , 2- Simplify
according to some rules and algorithms x,
2, , y, 2, , - 3- Convert
simplified expression to strings x2 y2
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• Write a program who could solve simple
  differential equations

gtgtgt def solve(equation , indep_var,
dep_var) gtgtgt solve(y y , x,
y)? A ex gtgtgt solve( y y 2 sin x ,
x, y)? A ex B cos x sin x
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• Examples of Logic
• Suppose we have the following facts
• All habitants of Bal Island are exactly
  truthful or lier
• A, B, C are habitants of Bal island
• A says All of us are lier
• B says At least one of us is lier
• Each of A, B, C are lier or truthful?
• (-gt algorithmic puzzles, Mohammad Ghodsi,
  Fatemi Publication)?

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• Examples of Logic
• We can solve this problem using search
• In this case we should try 8 (23) cases
• For example (A is lier, B is truthful, C is
  lier)?
• But if we had 100 persons we should search 2100
  states
• (2100 1267650600228229401496703205376)?
• This is practically impossible

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Problem Solving Using Logic

• We can solve some of problems using logical
  conclusions (reasoning)?
• By logical reasoning we can obtain new facts from
  existing facts
• Reasonings can be done according to logical roles
  in mathematics

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An Example of Logical Reasoning

• Suppose we have following facts
• Kamran is a student
• All students are humans
• All students like learning
• Know we can conclude following facts
• Kamran is a human
• Kamran like learning
• A human likes learning OR is not a student

• Suppose we have following facts
• Kamran is a student
• All students are humans
• All students like learning
• Know we can conclude following facts
• Kamran is a human
• Kamran like learning
• A human likes learning OR is not a student

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Knowledge Representation

• Before working with the data we should be able to
  represent and store them in computer.
• There are many ways for representing information
  in computers, example

Ali is tall -gt tall(Ali)? Ali is
bigger than Reza -gt bigger(Ali, Reza)?
Ali is brother of Reza -gt Ali
brotherOf(Reza)? Ali is tall and Reza is not fat
-gt tall(Ali) AND (NOT fat(Reza))? If Ali is a
human then he can speak -gt human(Ali) gt
canSpeak(Ali)? All humans are Male or Female -gt
for all x human(x) gt Male(x) OR Female(x)?
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Fuzzy Logic

• Assume following predicates
• My bag is at home.
• My book is in my bag.
• My brother is taller than me

• They are exactly True or False.

• So we can have some conclusions
• IF (My bag is at home) AND (My book is in
• may bag) THEN (My book is at home)?

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Fuzzy Logic

• We want to perform conclusions on the knowledge
  obtained from the real world
• But some or most of facts in the real word are
  not decisive (are not exactly true or false)?
• Look the facts below
• Ali is tall.
• The weather is hot.
• My book is large.
• It is about 2 meters high.

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Fuzzy Logic

• Fuzzy Logic suggests a solution
• In fuzzy logic facts are not exactly true or
  false they instead have degree of truth
• If we denote true by '1' and false by '0' then
  truth of a fact can be a number between '0' and
  '1'.
• For example truth of Ali is tall can be '0.9'
• We can define 'AND' , 'OR', 'NOT' and 'gt' in
  fuzzy logic such as ordinary logic.

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Fuzzy Logic

• Fuzzy Logic was created by Dr. Lotfi Zhdeh in
  1960 for the purpose of modeling uncertainty
  inherent in Natural Language
• Representing vague and often contradictory
  knowledge.
• Fuzzy logic is primarily used as the underlying
  logic of fuzzy expert systems

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Fuzzy Logic

• Example of Fuzzy Logic applications
• Pattern Recognition
• Control (Fuzzy Controllers)?
• Weather forecasting
• Economics
• Politics

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other fields of AI

• Evolutionary Computation (Genetic Algorithms,
  ...)?
• Artificial Neural Networks
• Robotics
• Expert Systems
• Image Processing and Machine Vision
• Data Mining
• ...