Introduction to Artificial Intelligence

Stuart Russell Peter Norvig

What is an A.I.? • “The exciting new effort to make computers think… machines with minds, in the full and literal sense” – Haugeland, 1985 • “The automation of activities that we associate with human thinking, activities, such as decision – making, problem solving, learning…” – Bellman, 1978

• “The art of creating machines that perform functions that require intelligence when performed by people.” – Kurzweil, 1990 • “The study of how to make computers do things at which, at the moment, people are better” – Rich and Knight, 1991

What is an A.I.? • “The study of mental faculties through the use of computational models” – Charniak and McDermott, 1985 • “The study of the computations that make it possible to perceive, reason and act” – Winston, 1992 • “Computational Intelligence is the study of design of intelligent agent” – Poole et al., 1998 • “AI… is concerned with intelligent behavior in artifacts” – Nilsson, 1998

Systems that think like humans

Systems that think rationally

“The exciting new effort to make computers think… machines with minds, in the full and literal sense” – Haugeland, 1985

“The study of mental faculties through the use of computational models” – Charniak and McDermott, 1985

“The automation of activities that we associate with human thinking, activities, such as decision – making, problem solving, learning…” – Bellman, 1978

“The study of the computations that make it possible to perceive, reason and act” – Winston, 1992

Systems that act like humans

Systems that act rationally

“The art of creating machines that perform functions that require intelligence when performed by people.” – Kurzweil, 1990 “The study of how to make computers do things at which, at the moment, people are better” – Rich and Knight, 1991

“Computational Intelligence is the study of design of intelligent agent” – Poole et al., 1998 “AI… is concerned with intelligent behavior in artifacts” – Nilsson, 1998

Thinking humanly: The cognitive approach • If we are going to say that a given program thinks like a human, we must have some way of determining how humans think. We need to get inside the actual workings of human minds. There are two ways to do this: though introspection – trying to catch our own thoughts as they go – and through psychological experiments. Once we have sufficiently precise theory of the mind, it becomes possible to express the theory as a computer program. If the program’s input/output and timing behaviors match corresponding human behaviors, that is evidence that some of the program’s mechanism could also be operating in humans.

Acting humanly: The Turing Test approach • Turing Test: designed by Alan Turing (1950) • Was designed to provide a satisfactory operational definition of intelligence.

Acting humanly: The Turing Test approach • The computer would need to possess the following capabilities: 1. Natural Language Processing – to enable to communicate successfully in English. 2. Knowledge Representation – to store what it knows or hears. 3. Automated Reasoning – to use the stored information to answer question and to draw new conclusion. 4. Machine Learning – to adapt to new circumstances and to detect and extrapolate patterns. 5. Computer Vision – to perceive objects 6. Robotics – to manipulate objects and move out.

Thinking rationally: The “laws of thought” approach • Aristotle – was one of the first to attempt to codify “right thinking ”. His syllogisms provided patterns for argument structures that always yielded correct conclusions when a given correct premises. • Ex: “Socrates is a man; all men are mortal; therefore, Socrates is mortal” • This initiate the field of LOGIC. Formal logic was developed in the late nineteenth century. This was the first step toward enabling computer programs to reason logically.

Acting rationally: The rational agent approach • Acting rationally means acting so as to achieve one's goals, given one's beliefs. • An agent is just something that perceives and acts. In the logical approach to AI, the emphasis is on correct inferences. This is often part of being a rational agent because one way to act rationally is to reason logically and then act on ones conclusions. But this is not all of rationality because agents often find themselves in situations where there is no provably correct thing to do, yet they must do something. • There are also ways to act rationally that do not seem to involve inference, e.g., reflex actions.

Acting rationally: The rational agent approach • The study of AI as rational agent design has two advantages: • It is more general than the logical approach because correct inference is only a useful mechanism for achieving rationality, not a necessary one. • It is more amenable to scientific development than approaches based on human behavior or human thought because a standard of rationality can be defined independent of humans. • Achieving perfect rationality in complex environments is not possible because the computational demands are too high.

The Foundation of Artificial Intelligence • Philosophy • Mathematics • Economics • Neuroscience • Psychology • Computer Engineering • Control Theory and Cybernetics • Linguistics