More Definitions Flashcards
Absolute Error
The difference between the actual number and the nearest representable value.
Abstract data type (ADT)
A data type whose properties are specified independently of any particular programming language.
Abstraction
Representation that is arrived at by removing unnecessary details.
Algorithm
A sequence of unambiguous instructions for solving a problem. It can be represented as a Turing machine program.
Application programming interface (API)
A layer of software that allows application programs to call on the services of the operating system.
Asynchronous serial data transmission
Transmission system in which the sender and receiver have separate clocks which are not kept synchronised. Instead the clocks are synchronised temporarily at the start of a transmission. The arrival of data cannot be predicted by the receiver; s a start bit is used to signal the arrival of data and to synchronise the transmitter and receiver temporarily.
Attribute
A property or characteristic of an entity (databases) or an object (OOP).
Automation
Turning an abstraction into a form that can be processed by a computer.
Bandwidth
For a transmission medium the range of signal frequencies it may transmit.
Base case
A value that has a solution which does not involve any reference to the general case solution.
Baud rate
The rate at which signals on a wire may change.
Bit rate
The number of bits transmitted per second.
Broadband
A multiple data channel system in which the bandwidth of the transmission medium carries several data streams at the same time.
Circular queue
When the array element with the largest possible index has been used the next element to join the queue reuses the vacated location at the beginning of the array.
Class definition
A template that can be used to create objects of that class.
Client
A computer that uses the services provided by a server.
Client-server system
A system in which some computers (the clients) request services provided by other computers (the servers).
Complexity of a problem
Taken to be the worst case complexity of the most efficient algorithm which solves the problem.
Composite key
A combination of attributes that uniquely identifies a tuple/record.
Composition
A type of association where the composite object has ownership of the objects within it. The objects that are part of the composite objects have a lifecycle determined by the composite object. If the composite object ceases to exist then they too will cease to exist.
Cryptography
The science of designing cipher systems.
Data transmission
Movement of data.
Database
A structured collection of data.
Database management system
A software system that enables the definition creation and maintenance of a database and which provides controlled access to this database.
Decryption
Using an algorithm and a key to convert encrypted message data into its plain text equivalent.
Degree of relationship
Between two entities it refers to the number of entity occurrences of one entity which are associated with just one entity occurrence of the other and vice versa.
Deterministic finite state machine (FSM)
An FSM that has just one next state for each pair of state and input symbols.
Directed graph
A diagram consisting of vertices joined by directed edges.
Dynamic allocation
Memory space is only allocated when required at runtime.
Dynamic data structure
The memory taken up by the data structure varies at run time.
Dynamic web page content
Content that is generated when the web browser request is received.
Embedded computer system
A dedicated computer system with a limited or non-existent user interface and designed to operate completely or largely autonomously from within other machinery.
Encapsulation
Combining a record with the procedures and functions that manipulate it to form a new data type; a class in OOP.
Encryption
Using an algorithm and a key to convert message data into a form that is not understandable without that key.
Entity
An object, person, event or thing of interest about which data are recorded.
Evaluation
A systematic assessment of whether something meets its objectives or specifications and how well it meets the latter in terms of effectiveness usability maintainability.
Explorer’s problem
The solution finds a route that traverses each road exactly once before returning to the starting point.
Exponential time algorithm
An algorithm whose execution time grows exponentially with input size.
Feasibility study
A study that investigates the potential of a new system.
Finite state machine
A finite state machine is a model of computation for a machine that is always in one of a fixed number of states. The state of the machine can be changed according to transition rules based upon the input that it receives and its current state. Some finite state machines produce output as they carry out transitions whilst others simply produce a yes/no response at the end of processing their input.
Floating point notation
A real number represented by a sign some significant digits (the mantissa) and a power of 2 (the exponent).
Foreign key
An attribute in one table that is a primary key in another table.
Gateway
A device used to connect networks using different protocols so that information can be successfully passed from one system to another.
General case
The solution in terms of itself for a value n.
Graph
A diagram consisting of vertices joined by edges.
Halting problem
The unsolvable problem of writing a program that can tell whether a given program and its inputs will halt without running the given program.
Halting state
A state that has no outgoing transition.
Handshaking protocol
The sending and receiving devices exchange signals to establish that they are each ready to initiate data transfer.