Lecture 1: Introduction

*Briefly discuss Newell and Simon's contribution to AI*

*General Problem Solver (G.P.S)* was a computer program, created in *1959* by _Herbert A. Simon, J.C. Shaw, and Allen Newell_ that was intended to work as a universal problem solver machine.

*Acting Humanly* : Turing Test

- Predicted that *by 2000* , a machine might have a *30%* chance of fooling a person for 5 minutes. - Turing defined *intelligent behaviour* as the ability to achieve human-level performance in all cognitive tasks, sufficient to fool an interrogator.

*Advantages of the Rational-agent Approach*

1. It is more general than the "laws of thought" approach because correct inference is just one of several possible mechanisms for achieving rationality. 2. It is more amenable to scientific development than are approaches based on human behavior or human thought.

*Problems with Thinking Rational approach*

1. It is not easy to take informal knowledge and state it in the formal terms required by logical notation, particularly when the knowledge is less than 100% certain 2. There is a big difference between solving a problem "in principle" and solving it in practice. Even problems with just a few hundred facts can exhaust the computational resources of any computer unless it has some guidance as to which reasoning steps to try first

*Organization of AI*

1. Systems that *think like humans* 2. Systems that *act like humans* 3. Systems that *think rationally* 4. Systems that *act rationally*

*What is Cognitive Science?*

A discipline which brings together computer models from AI and experimental techniques from psychology to construct precise and testable theories of the human mind.

*What is a rational agent?*

A rational agent is one that acts so as to achieve the best outcome or, when there is uncertainty, the best expected outcome.

*Briefly discuss Alan Turing's contribution to AI.*

Alan Turing invented Computer Science around *1935* leading rapidly to interest in creating machine intelligence. He formulate his famous test for intelligence in his "Computing Machinery and Intelligence" (Mind 1950), despite the arguments among psychologists, philosophers and himself about the concept of intelligence.

*Acting Rational* : _Rational Agent Cont'd_

All the skills needed for the Turing Test also allow an agent to act rationally.

*What kind of problems could the GPS solve?*

Any problem that: - can be expressed as a set of *WFFs* or *Horn clauses* *and* - that constitute a digraph with one or more sources and sinks can be solved, in principle, by GPS.

*Hubert Dreyfuss* 1965, 1993

Hubert Dreyfuss has pushed many objections to the possibility of an Artificial Intelligence. *The three most notable are:* *1. The embodiment objection* Human thinking is embodied, the essence of computation is universality i.e. disembodied *2. Context objection* Human thinking has a holistic context, computer rules are context free *3. Skill Objection* Human intellect is an inarticulable skill and computers "intellect" involves following rules

*The cognitive modeling approach* Cont'd

If the program's input-output behavior matches corresponding human behavior, that is evidence that some of the program's mechanisms could also be operating in humans. Newell and Simon, who created GPS, were not content merely to have their program solve problems correctly. They were more concerned with comparing the trace of its reasoning steps to traces of human subjects solving the same problems.

*Acting Rational* : _Rational Agent_

In the "laws of thought" approach to AI, the emphasis was on correct inferences. Making correct inferences is sometimes part of being a rational agent, because one way to act rationally is to reason logically to the conclusion that a given action will achieve one's goals and then to act on that conclusion. On the other hand, correct inference is not all of rationality; in some situations, there is no provably correct thing to do, but something must still be done.

*What is the principle behind GPS?*

Problem-solving behaviour involves means-ends-analysis, i.e., breaking a problem down into subcomponents (subgoals) and solving each of those.

*Define Rationality*

Rationality is the quality or state of being reasonable, based on facts or reason.

*Thinking Rationally* : Laws of Thought

The Greek philosopher Aristotle was one of the first to attempt to codify "right thinking," that is, irrefutable reasoning processes. His syllogisms provided patterns for argument structures that always yielded correct conclusions when given correct premises These laws of thought were supposed to govern the operation of the mind; their study initiated the field called logic.

*Problems with Cognitive Modelling*

The available theories do not explain anything resembling human-level general intelligence

*What is artificial intelligence?*

The theory and development of computer systems that are able to perform tasks normally requiring human intelligence

*Thinking Humanly* : Cognitive Modelling 1960's

There are three ways to get _inside_ the actual workings of human minds: *Through introspection* - trying to catch our own thoughts as they go by *Through psychological experiments* - observing a person in action *Through brain imaging* - observing the brain in action

*Proposed Components of AI*

To pass this test systems would need: - Natural Language Processing - Knowledge Representation - Automated Reasoning - Machine Learning

*Flaws in the Turing test*

Turing test is not: - reproducible - constructive - amenable to mathematical analysis