Foundation of AI

 

Foundation of AI

A brief history of the disciplines that contributed ideas, viewpoints, and techniques to AI are as follows:

1. Philosophy(the study of the fundamental nature of knowledge):

 

 Can formal rules be used to draw valid conclusions?

 How does the mind arise from a physical brain?

 Where does knowledge come from?

 How does knowledge lead to action?

 

 Aristotle (384–322 B.C.), was the first to formulate a precise set of laws governing the rational part of the mind. He developed an informal system of syllogisms for proper reasoning, which in principle allowed one to generate conclusions mechanically, given initial premises.

 

Eg.

all dogs are animals;

all animals have four legs;

therefore all dogs have four legs

 Thomas Hobbes (1588–1679) proposed that reasoning was like numerical computation that ―we add and subtract in our silent thoughts.‖

 Rene Descartes (1596–1650) gave the first clear discussion of the distinction between mind and matter and of the problems that arise.

 The empiricism movement, starting with Francis Bacon's (1561— 1626).

 The confirmation theory of Carnap and Carl Hempel (1905-1997) attempted to analyze the acquisition of knowledge from experience.

 Carnap's book The Logical Structure of the World (1928) defined an explicit computational procedure for extracting knowledge from elementary experiences. It was probably the first theory of mind as a computational process.

 The final element in the philosophical picture of the mind is the connection between knowledge and action. This question is vital to Al because intelligence requires action as well as reasoning.

 

2. Mathematics

 What are the formal rules to draw valid conclusions?

 What can be computed?

 

Formal science required a level of mathematical formalization in three fundamental areas: logic, computation, and probability.

Logic:

George Boole (1815–1864), who worked out the details of propositional, or Boolean, logic.

In 1879, Gottlob Frege (1848–1925) extended Boole’s logic to include objects and relations, creating the firstorder logic that is used today.

First order logic – Contains predicates, quantifiers and variables

E.g. Philosopher(a) ⇒ Scholar(a)

∀x, effect_carona(x) ⇒ quarantine(x)

∀x, King(x) ^ Greedy (x) ⇒ Evil (x)

Alfred Tarski (1902–1983) introduced a theory of reference that shows how to relate the objects in a logic to objects in the real world.

Logic and Computation: The first nontrivial algorithm is thought to be Euclid’s algorithm for computing greatest common divisors(GCD).

 Beside logic and computation, the third great contribution of mathematics to AI is the probability. The Italian Gerolamo Cardanao (1501-1576) first framed the idea of probability, describing it in terms of the possible outcomes of gambling events.

 Thomas Bayes (1702-1761) proposed a rule for updating probabilities in the light of new evidence. Baye’s rule underlies most modern approaches to uncertain reasoning in AI systems.

 

3. Economics

 How should we make decisions so as to maximize payoff?

 How should we do this when the payoff may be far in the future?

 

 The science of economics got its start in 1776, when Scottish philosopher Adam Smith treat it as a science, using the idea that economies can be thought of as consisting of individual agents maximizing their own economic well being.

 Decision theory, which combines probability theory with utility theory, provides a formal and complete framework for decisions (economic or otherwise) made under uncertainty— that is, in cases where probabilistic descriptions appropriately capture the decision maker’s environment.

 Von Neumann and Morgenstern’s development of game theory included the surprising result that, for some games, a rational agent should adopt policies that are randomized. Unlike decision theory, game theory does not offer an unambiguous prescription for selecting actions.

 

4. Neuroscience: How do brain process information?

 Neuroscience is the study of the nervous system, particularly the brain.

 335 B.C. Aristotle wrote, "Of all the animals, man has the largest brain in proportion to his size."

 Nicolas Rashevsky (1936, 1938) was the first to apply mathematical models to the study of the nervous system.

 

Fig. A neuron cell of human brain.

 The measurement of intact brain activity began in 1929 with the invention by Hans Berger of the electroencephalograph (EEG).

 The recent development of functional magnetic resonance imaging (fMRI) (Ogawa et al., 1990; Cabeza and Nyberg, 2001) is giving neuroscientists unprecedentedly detailed images of brain activity, enabling measurements that correspond in interesting ways to ongoing cognitive processes.

 

5. Psychology: How do humans and animals think and act?

 

 Behaviorism movement, led by John Watson(1878-1958). Behaviorists insisted on studying only objective measures of the percepts(stimulus) given to an animal and its resulting actions(or response). Behaviorism discovered a lot about rats and pigeons but had less success at understanding human.

 Cognitive psychology, views the brain as an information processing device. Common view among psychologist that a cognitive theory should be like a computer program.(Anderson 1980) i.e. It should describe a detailed information processing mechanism whereby some cognitive function might be implemented.

 

6. Computer engineering: How can we build an efficient computer?

 

 For artificial intelligence to succeed, we need two things: intelligence and an artifact. The computer has been the artifact(object) of choice.

 The first operational computer was the electromechanical Heath Robinson, built in 1940 by Alan Turing's team for a single purpose: deciphering German messages.

 The first operational programmable computer was the Z-3, the invention of KonradZuse in Germany in 1941.

 The first electronic computer, the ABC, was assembled by John Atanasoff and his student Clifford Berry between 1940 and 1942 at Iowa State University.

 The first programmable machine was a loom, devised in 1805 by Joseph Marie Jacquard (1752-1834) that used punched cards to store instructions for the pattern to be woven.

 

7. Control theory and cybernetics: How can artifacts operate under their own control?

 

 Ktesibios of Alexandria (c. 250 B.C.) built the first self-controlling machine: a water clock with a regulator that maintained a constant flow rate. This invention changed the definition of what an artifact could do.

 Modern control theory, especially the branch known as stochastic optimal control, has as its goal the design of systems that maximize an

objective function over time. This roughly OBJECTIVE FUNCTION matches our view of Al: designing systems that behave optimally.

 Calculus and matrix algebra- the tools of control theory

 

The tools of logical inference and computation allowed AI researchers to consider problems such as language, vision, and planning that fell completely outside the control theorist’s purview.

8. Linguistics: How does language relate to thought?

 

 In 1957, B. F. Skinner published Verbal Behavior. This was a comprehensive, detailed account of the behaviorist approach to language learning, written by the foremost expert in the field.

 Noam Chomsky, who had just published a book on his own theory, Syntactic Structures.Chomsky pointed out that the behaviorist theory did not address the notion of creativity in language.

 Modern linguistics and AI were ―born‖ at about the same time, and grew up together, intersecting in a hybrid field called computational linguistics or natural language processing.

 The problem of understanding language soon turned out to be considerably more complex than it seemed in 1957. Understanding language requires an understanding of the subject matter and context, not just an understanding of the structure of sentences.

 knowledge representation (the study of how to put knowledge into a form that a computer can reason with)- tied to language and informed by research in linguistics.