| slovo | definícia |
data redundancy
(foldoc) | data redundancy
Any technique that stores or
transmits extra, derived data that can be used to detect or
repair errors, either in hardware or software. Examples are
parity bits and the cyclic redundancy check.
If the cost of errors is high enough, e.g. in a
safety-critical system, redundancy may be used in both
hardware AND software with three separate computers programmed
by three separate teams ("triple redundancy") and some system
to check that they all produce the same answer, or some kind
of majority voting system.
The term is not typically used for other, less beneficial,
duplication of data.
2. The proportion of a message's gross
information content that can be eliminated without losing
essential information.
Technically, redundancy is one minus the ratio of the actual
uncertainty to the maximum uncertainty. This is the fraction
of the structure of the message which is determined not by the
choice of the sender, but rather by the accepted statistical
rules governing the choice of the symbols in question.
[Shannon and Weaver, 1948, p. l3]
(2010-02-04)
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