Cao Hoang Tru

CSE Faculty - HCMUT

1

19 October 2009

What is AI?

Acting rationallyActing humanly

Thinking rationallyThinking humanly

Cao Hoang Tru

CSE Faculty - HCMUT

2

19 October 2009

Acting Humanly: The Turing Test

• Alan Turing (1912-1954)

• “Computing Machinery and Intelligence” (1950)

Human Interrogator

Human

AI System

Imitation Game

Cao Hoang Tru

CSE Faculty - HCMUT

3

19 October 2009

Acting Humanly: The Turing Test

• Predicted that by 2000, a machine might have a 30% chance of fooling a lay person for 5 minutes.

• Anticipated all major arguments against AI infollowing 50 years.

• Suggested major components of AI: knowledge, reasoning, language, understanding, learning.

Cao Hoang Tru

CSE Faculty - HCMUT

4

19 October 2009

Thinking Humanly: Cognitive Modelling

• Not content to have a program correctly solving a problem.

More concerned with comparing its reasoning steps to traces of human solving the same problem.

• Requires testable theories of the workings of the human mind: cognitive science.

Cao Hoang Tru

CSE Faculty - HCMUT

5

19 October 2009

Thinking Rationally: Laws of Thought

• Aristotle was one of the first to attempt to codify “right thinking”, i.e., irrefutable reasoning processes.

• Formal logic provides a precise notation and rules for representing and reasoning with all kinds of things in the world.

• Obstacles:− Informal knowledge representation.

− Computational complexity and resources.

Cao Hoang Tru

CSE Faculty - HCMUT

6

19 October 2009

Acting Rationally

• Acting so as to achieve one’s goals, given one’s beliefs.

• Does not necessarily involve thinking.

• Advantages:− More general than the “laws of thought” approach.

− More amenable to scientific development than

human-based approaches.

Cao Hoang Tru

CSE Faculty - HCMUT

7

19 October 2009

AI = Algorithms + Intelligence

Cao Hoang Tru

CSE Faculty - HCMUT

8

19 October 2009

AI = Algorithms + Intelligence

How to

algorithmize

solutions to

the problems

that human

can solve?

Cao Hoang Tru

CSE Faculty - HCMUT

9

19 October 2009

AI = Algorithms + Intelligence

How to

algorithmize

solutions to

the problems

that human

can solve?

Problem

solving as

searching

Cao Hoang Tru

CSE Faculty - HCMUT

10

19 October 2009

What is Knowledge Engineering?

Stuart Russell:

"The process of building a knowledge base"

Cao Hoang Tru

CSE Faculty - HCMUT

11

19 October 2009

What is Knowledge Engineering?

John Sowa:

"The application of logic and ontology to the task of building computable models of some domain for some purpose"

(ontology = the study of existence; "a catalog of types of things that are assumed to exist in a domain of interest")

Cao Hoang Tru

CSE Faculty - HCMUT

12

19 October 2009

What is Knowledge Engineering?

A knowledge engineer:

• Investigates a particular domain

• Determines what concepts are important

• Creates a formal representation of the objects and relations

Cao Hoang Tru

CSE Faculty - HCMUT

13

19 October 2009

What is Knowledge Engineering?

Building a knowledge base:

1. Decide what to talk about

2. Decide on a vocabulary of predicates, functions, and constants

3. Encode general knowledge about the domain

4. Encode a description of the specific problem instance

5. Pose queries to the inference procedure and get answers

Cao Hoang Tru

CSE Faculty - HCMUT

14

19 October 2009

Principles of Knowledge Representation

Knowledge Representation is:

1. A surrogate

2. A set of ontological commitments

3. A fragmentary theory of intelligent reasoning

4. A medium for efficient computation

5. A medium of human expressions

Davis, R. & Schrobe, H. & Szolovits, P. (1993), What is a Knowledge Representation?. AI Magazine (14) 17-33.

Cao Hoang Tru

CSE Faculty - HCMUT

15

19 October 2009

Homework

Reading:

• Turing, A. (1950), Computing Machinery and Intelligence. Mind (236) 433-460.

• Davis, R. & Schrobe, H. & Szolovits, P. (1993), What is a Knowledge Representation?. AI Magazine (14) 17-33.