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A reasoning process by which a new premise is derived from one or more given premises. A premise is either a fact or a rule. The term "inference" also refers to the result of the process.

inference engine:
The component of an expert system that applies principles of reasoning to draw conclusions from the information stored in a knowledge base.

infinite loop:
A loop whose execution can be terminated only by external intervention.

infinite pad method:
In optical character recognition, a method of measuring reflectance of a paper stock such that doubling the number of backing sheets of the same stock will not change the measured reflectance.

infix notation:
A method of forming mathematical expressions, governed by rules of operator precedence and using paired delimiters such as parentheses, in which the operators are dispersed among the operands, each operator indicating the operation to be performed on the operands or the intermediate results adjacent to it; for example, A added to B and the sum multiplied by C is represented by the expression (A + B) × C. Another example is P AND the result of Q AND R is represented by the expression P & (Q & R). If it is desired to distinguish the case in which there are more than two operands for an operator, the phrase "distributed infix notation" may be used. Contrast with postfix notation, prefix notation.

(1) The meaning that is currently assigned to data by means of the conventions applied to these data. (Figure 16 - Interrelationships of data). (2) In information processing, any fact, concept, or meaning derived from data and associated context or selected from knowledge. (3) In a conceptual schema language, any kind of knowledge about things, facts, or concepts of a universe of discourse that is exchangeable among users. (4) In information theory, knowledge that reduces or removes uncertainty about the occurrence of a specific event from a given set of possible events.

information area:
Synonym for information zone.

informational cohesion:
Cohesion in which the activities of a module are performed on a common data structure but use independent entry points and code.

information analysis:
A systematic investigation of information and its flow in a real or planned system.

information base:
A collection of sentences, consistent with each other and with the conceptual schema, expressing the propositions that hold for a specific entity world.

information bit:
A bit used for the representation of user data, rather than for control purposes.

information content:
A quantitative measure of information about the occurrence of an event of definite probability, equal to the logarithm of the reciprocal of this probability, that is in mathematical notation:
I(x) = log [1 / p(x)] = - log  p(x)
where p(x) is the probability of the occurrence of the event x. Example: Let {a,b,c} be a set of three events and let p(a) = 0.5, p(b) = 0.25 and p(c) = 0.25 be the probabilities of their occurrences. The information content of these events are:
I(a) = log2 [1/(0.50)] Sh = 1 Sh;
I(b) = log2 [1/(0.25)] Sh = 2 Sh;
  I(c) = log2 [1/(0.25)] Sh = 2 Sh.
For a set of equiprobable events, the information content of each event is equl to the decision content of the set.

information feedback system:
A data transmission system that uses an echo check to verify the accuracy of the transmission.

information flow control:
In computer security, a procedure used to ensure that information transfers within and from a system are made in accordance with security policy. Information flow control is more restrictive than access control.

information hiding:
The principle of denying access to or knowledge of a language construct or specific details thereof, except for those details considered essential for the user to know. One tool used for information hiding is encapsulation.

information interchange:
The process of sending and receiving data in such a manner that the information content or meaning assigned to the data is not altered during the transmission.

information management:
In an information processing system, the functions of controlling the acquisition, analysis, retention, retrieval, and distribution of information.

information object:
In electronic mail, a set of data that represents an entity of information; for example: a message, a probe, a report. The information may be represented by pure text or may include sounds or images.

information processing:
The systematic performance of operations upon information, that is the meaning of data, including required data processing and may include operations such as data communication and office automation. In document preparation, the processing of keystrokes to create character strings, the automatic pagination on the screen, etc., is data processing. On the other hand, when a grammar checker recommends a change in the content, it has performed at least rudimentary information processing because it has given meaning to certain prepositions, has recognized certain verbs (especially conjugation of the verb "to be"), recognized nouns in singular and plural forms, etc. The term information processing must not be used as a synonym for data processing. A data processing system may also perform some information processing (e.g., a network bridge or router). All information processing systems process data as their fundamental capability to achieve the effect of information processing. (Figure 16 - Interrelationships of data).

information processing system:
One or more data processing systems and devices, such as office and communication equipment, that perform information processing.

information processor:
In a conceptual schema language, the mechanism that, in response to a command, executes an action on the conceptual schema, or on the information base.

information provider:
An organization that collects and provides information for users. The information can be provided directly to users or via a content provider and an access provider.

information resource:
Information that an enterprise treats as a corporate resource for decision making and problem solving.

information resource dictionary (IRD):
A collection of entities, relationships, and attributes used by an organization to model its information environment.

information resource dictionary schema:
The model of the logical structure of the information resource dictionary that consists of descriptors such as entity types, relationship types, and attribute types.

information resource dictionary system (IRDS):
Software that provides facilities for recording, storing, and processing descriptions of an organization's significant information and information processing resources.

information resource management (IRM):
The planning, organizing, and controlling data resources consistent with the overall goals and objectives of an enterprise.

information retrieval (IR):
Actions, methods, and procedures for obtaining information on a given subject from stored data.

information security:
The concepts, techniques, technical measures, and administrative measures used to protect information assets from deliberate or inadvertent unauthorized acquisition, damage, disclosure, manipulation, modification, loss, or use.

information separator (IS):
Any control character used to delimit like units of data in a hierarchic arrangement of data. The name of the separator does not necessarily indicate the units of data that it separates. Synonymous with separating character.

information system:
(1) An information processing system together with associated organizational resources such as human, technical, and financial resources, that provides and distributes information. (2) In databases, the conceptual schema, information base, and information processor, forming together a system for keeping and manipulating information.

information system abuse:
Willful or negligent activity that affects the availability, confidentiality, or integrity of information systems resources.

information theory:
The branch of learning concerned with quantitative measures of information. The term information is used here in a technical sense and is generally applied to the syntactic level of messages rather that the semantic level. It thus relates more to the statistical properties of the system rather than any meaning of the data being passed. The original title of Shannon's paper was "A Mathematical Theory of Communication" and rarely used the phrase 'information theory'. Contrast with communication theory.

information technology (IT):
The art and applied sciences that deal with data and information. Examples are capture, representation, processing, security, transfer, interchange, presentation, management, organization, storage, and retrieval of data and information.

information track:
A track on a disk containing user data.

information zone:
A zone in an optical disk than contains data tracks. Synonymous with information area.

infrared mouse:
A mouse that interfaces with a computer through an infrared link and not via a cord.

infrared port:
An optical port on a computer for interfaceing with an infrared-capable device to achieve communication without the use of cables.

(1) The copying of all or part of the internal structure and of the set of operations from one class to a subordinate class. (2) In artificial intelligence and in a knowledge representation, default transmission of class characteristics to one or more of its subclasses. There is multiple inheritance in non-hierarchical knowledge representations.

inherited error:
An error carried forward from a previous step in a sequential process.

inhibiting signal:
A signal that prevents the occurrence of an event.

initial condition mode:
That set-up mode of an analog computer during which the integrators are inoperative and the initial conditions are set. Synonymous with reset mode.

The operation of setting a functional unit or data to a starting state. Example: formatting a medium, setting initial values for program variables.

To give a data value to a data object at the beginning of its lifetime.

initial program load (IPL):
Synonym for bootstrap.

initial program loader (IPL):
A bootstrap loader that is used in a computer to load that part of an operating system needed to load the remainder of the operating system.

In computer graphics, creating a line by moving the locator over the screen and leaving a trail behind the locator in the manner of a pen drawing a line on paper.

ink jet printer:
A nonimpact printer that forms the characters or unique images by projecting ionized particles or droplets of ink onto the output medium.

inline recovery:
Recovery performed by resuming work at a safe point preceding the occurrence of a failure.

Pertaining to a device, process, or input/output channel involved in an input process, or to the associated data or states. The word "input" may be used in place of "input data", "input signal", or "input process" when such a usage is clear in a given context.

input channel:
A channel for conveying data to a device or gate.

input data:
Data entered into a data processing system or any of its parts for storage or processing.

input device:
Synonym for input unit.

input layer:
In artificial neural networks, a layer whose artificial neurons receive signals from external sources. By extension, the term "input layer" may also include source nodes.

input medium:
A medium through which a system acquires data; for example, sound as received by a microphone.

input neuron:
An artificial neuron that receives signals from external sources.

Pertaining to a device, process, or channel involved in an input/output process, or to the associated data or states. The phrase "input/output" may be used in place of "input/output data", "input/output signal", or "input/output process" when such a usage is clear in a given context. Synonymous with I/O.

input/output channel:
A functional unit that handles the transfer of data between internal storage and peripheral equipment. Synonymous with I/O channel.

input/output controller (IOC):
A functional unit that controls one or more input/output channels. Synonymous with I/O controller.

input/output device:
Synonym for input/output unit.

input/output port:
Synonym for port.

input/output process:
The process of entering data into a functional unit for storage or processing, or of transferring data outside of that functional unit, possibly concurrently. Synonymous with I/O process.

input/output unit:
A device by which data can be entered into or conveyed out of a functional unit. Synonymous with input/output device, I/O unit.

input primitive:
In computer graphics, an item of data obtained from an input unit such as a keyboard, choice device, locator, pointing device, or valuator device.

input process:
The process of entering data into a functional unit for storage or processing.

input-process-output chart:
A diagram of a software system or module, consisting of a rectangle on the left listing inputs, a rectangle in the center listing processing steps, a rectangle on the right listing outputs, and arrows connecting inputs to processing steps and processing steps to outputs. Synonymous with IPO chart . (Figure 34 - Input-process-output chart).

input protection:
For analog input channels, the protection against overvoltages that may be applied between any two input connectors or between any input connector and ground.

input state:
The state that prevails on a specified input channel.

input stream:
Synonym for job stream.

input subsystem:
That part of a process interface system that transfers data from the technical process to the process computer system.

input unit:
A device by which data can be entered into a computer. Synonymous with input device.

inquiry station:
A user terminal primarily for the interrogation of a computer.

(1) To introduce data between previously stored items of data. (2) A function or mode that enables a user to introduce additional text within existing text; the existing text is automatically rearranged to accommodate the addition.

instance-based learning:
Synonym for learning from examples.

The creation of an object of a particular class that conforms to the object type for that class.

The designation of an operation and the identification of any associated operands.

instruction address:
(1) The address of an instruction word. (2) The address that must be used to fetch an instruction.

instruction address register:
A register used to hold the address of an instruction to be executed. It may include counter features so as to automatically increment to the next instruction address. Synonymous with program register, instruction pointer register, instruction counter, program counter.

instruction code:
Synonym for operation code.

instruction control unit:
In a processor, the part that retrieves instructions, interprets each instruction, and applies signals to the arithmetic and logic unit and other parts in accordance with this interpretation.

instruction counter:
Synonym for instruction address register.

instruction format:
The layout of the constituent parts of an instruction.

instruction length:
The number of words, bytes, or bits needed to store a machine instruction.

instruction modifier:
A word or part of a word that is used to alter an instruction.

instruction pointer:
Synonym for instruction address register.

instruction register:
A register that is used to hold an instruction for interpretation.

instruction repertoire:
Synonym for instruction set.

instruction set:
The complete set of instructions recognized by a given computer or provided by a given programming language. Synonymous with instruction repertoire.

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