## A* algorithm

Overview page. Subjects: Computing.

A member of the class of best-first heuristic search techniques that attempt to find a “best” path from a given start node to a designated goal node in a problem graph. An evaluation...

## Aalen model

Overview page. Subjects: Probability and Statistics.

A linear regression model describing the manner in which the expected value of a response variable, *Z*(*t*), depends on explanatory variables *X*
_{1}(*t*),…, *X*
*null...*

## Abandonment

Overview page. Subjects: Computing.

A term used to describe the user of the Internet who stops some process they are involved in and does not return to it. For example a user who has purchased some items, partially filled...

## Abandonware

Overview page. Subjects: Computing.

Software that is no longer being sold by the company that developed and marketed it.

## abduction

Overview page. Subjects: Arts and Humanities — Computing.

An inference process widely used in artificial intelligence, particularly in expert systems and rule-based systems. In diagnosis, for example, there may be a rule like “if measles then red...

## abelian group

Overview page. Subjects: Mathematics.

Suppose that *G* is a group with the operation ￮. Then *G* is abelian if the operation ￮ is commutative; that is, if, for all elements *a* and *b* in *G*, *a* ￮ *b*=*b* ￮ *a*.

## Abel's test

Overview page. Subjects: Mathematics.

A test for the convergence of an infinite series which states that if ∑*a*
_{
n
} is a convergent sequence, and {*b*
_{
nnull...}

## ABEND

Overview page. Subjects: Computing.

Acronym for ABnormal END of task. Normally this occurs when a computer crashes or a communication link fails.

## ablative

Overview page. Subjects: Computing.

Designating an optical recording technique in which the heat generated by the recording beam melts or vaporizes a small area of the recording medium, leaving the underlying layer (with a...

## abnormal termination

Overview page. Subjects: Computing.

A termination to a process brought about by the operating system when the process reaches a point from which it cannot continue, e.g. when the process attempts to obey an undefined...

## ABONE

Overview page. Subjects: Computing.

The Asian-Pacific Internet backbone network that connects users throughout East and South Asia without the need to send data via European or North American networks.

## abort

Overview page. Subjects: Computing.

(of a process) To undergo or cause abnormal termination. Abortion may be a voluntary act by the process, which realizes that it cannot reach a successful conclusion, or may be brought about...

## above

Overview page. Subjects: Mathematics.

Greater than. The limit of a function at *a* from above is the limit of *f*(*x*) as *x* → *a* for values of *x*>*a*. It is of particular importance when *f* (*x*) has a discontinuity at *a*, i.e. where the...

## above the fold

Overview page. Subjects: Computing — Business and Management.

When a Web page is displayed in a browser the area of the page that is displayed is referred to as being above the fold. The contents that lie below are known as below the fold. The term is...

## Abraham de Moivre

Overview page. Subjects: Probability and Statistics.

(1667–1754; b. Vitry, France; d. London, England)

French mathematical prodigy. De Moivre studied at U Sedan when aged eleven, and later at U Saumur and the Sorbonne. In 1688 he...

## Abraham Wald

Overview page. Subjects: Probability and Statistics — Economics.

(1902–50; b. Cluj, Romania; d. Travancore, India)

Hungarian geometer and statistician. Wald gained his PhD in geometry in 1931 from U Vienna. In 1938, on the Nazi seizure of...

## absolute address

Overview page. Subjects: Computing.

A unique number that specifies a unique location within the address space where an operand is to be found/deposited, or where an instruction is located. It generally specifies a memory...

## absolute code

Overview page. Subjects: Computing.

Program code in a form suitable for direct execution by the central processor, i.e. code containing no symbolic references. See also machine code.

## absolute difference

Overview page. Subjects: Probability and Statistics.

The absolute value of the difference between two numbers. See also mean deviation.