4.1 abstraction and automation

algorithms

a sequence of steps that can be followed to complete a task, which always terminates

pseudocode

a way of writing algoithms which can be understood without the need for knowledge of a specific programming language

assignment

the process of giving a value to a variable or constant

in pseudocode:

var/const ← val

sequence

instructions that follow on from one another

in pseudocode, instructions are written in the order in which they appear unless a looping or branching instruction changes this

selection

the process of choosing an action to take based off the result of a comparison

in pseudocode:

IF (comparison) THEN

action

ELSE

action

END IF

(ELSE IF can also be used between IF and ELSE)

iteration

the process of repeating an instruction

in pseudocode:

FOR number ←start to end

action

ENDFOR

or

or WHILE (comparison)

action

ENDWHILE

abstraction

the process of simplifying a problem by removing unnecessary details, can be either representational or by generalisation

representational abstraction

an abstraction of a problem created by simply removing unnecessary details

abstraction by generalisation/categorisation

a grouping of things by common characteristics, where groups may be connected through hierarchical relationships

information hiding

the process of hiding all details of an object that do not contribute to the solution of the problem

procedural abstraction

the process of breaking down a complex model into a series of procedures that follow specific steps

the actual values used in solving the problem are abstracted away

functional abstraction

the process of breaking down a complex model into a function that performs specific tasks without considering the method (i.e. by calling procedures but not specifying their steps)

data abstraction

the process of hiding complex details about how data is represented to produce a simplified representation, which allows new kinds of data structures to be created from previously defined data structures (abstract data types)

problem abstraction/reduction

details are removed from a problem until it is represented in a way which is easier to solve (it may be reduced down to a problem, or group of problems, which already have algorithms to solve them)

decomposition

the division of a problem into a smaller series of sub-problems, which may be solved individually or decomposed further until all parts of the original problem have been solved

composition

the combination of procedures to form a system capable of solving complex problems which have previously been decomposed into smaller problems

automation

the process of creating a computerised model of a real-life situation and putting it into action

i.e. by putting abstractions of real world phenomena into algorithms and data structures and combining these into a program