redundancy

redundancy
    n 1: repetition of messages to reduce the probability of errors
         in transmission
    2: the attribute of being superfluous and unneeded; "the use of
       industrial robots created redundancy among workers" [syn:
       {redundancy}, {redundance}]
    3: (electronics) a system design that duplicates components to
       provide alternatives in case one component fails
    4: repetition of an act needlessly
    

Redundance \Re*dun"dance\ (r?*d?n"dans), Redundancy
\Re*dun"dan*cy\ (-dan*s?), n. [L. redundantia: cf. F.
   redondance.]
   [1913 Webster]
   1. The quality or state of being redundant; superfluity;
      superabundance; excess.
      [1913 Webster]

   2. That which is redundant or in excess; anything superfluous
      or superabundant.
      [1913 Webster]

            Labor . . . throws off redundacies.   --Addison.
      [1913 Webster]

   3. (Law) Surplusage inserted in a pleading which may be
      rejected by the court without impairing the validity of
      what remains.
      [1913 Webster]
    

redundancy

   1. <architecture, parallel> The provision of multiple
   interchangeable components to perform a single function in
   order to provide resilience (to cope with failures and
   errors).  Redundancy normally applies primarily to hardware.
   For example, a {cluster} may contain two or three computers
   doing the same job.  They could all be active all the time
   thus giving extra performance through {parallel processing}
   and {load balancing}; one could be active and the others
   simply monitoring its activity so as to be ready to take over
   if it failed ("warm standby"); the "spares" could be kept
   turned off and only switched on when needed ("cold standby").
   Another common form of hardware redundancy is {disk
   mirroring}.

   Redundancy can also be used to detect and recover from errors,
   either in hardware or software.  A well known example of this
   is the {cyclic redundancy check} which adds redundant data to
   a block in order to detect corruption during storage or
   transmission.  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.

   2. <communications> 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]

   (1995-05-09)
    

REDUNDANCY. Matter introduced in an answer, or pleading, which is foreign to 
the bill or articles. 
     2. In the case of Dysart v. Dysart, 3 Curt. Ecc. R. 543, in giving the 
judgment of the court, Dr. Lushington says: "It may not, perhaps, be easy to 
define the meaning of this term [redundant] in a short sentence, but the 
true meaning I take to be this: the respondent is not to insert in his 
answer any matter foreign to the articles he is called upon to answer, 
although such matter may be admissible in a plea; but he may, in his answer, 
plead matter by way of explanation pertinent to the articles, even if such 
matter shall be solely in his own knowledge and to such extent incapable of 
proof; or he may state matter which can be substantiated by witnesses; but 
in this latter instance, if such matter be introduced into the answer and 
not afterwards put in the plea or proved, the court will give no weight or 
credence to such part of the answer." 
     3. A material distinction is to be observed between redundancy in the 
allegation and redundancy in the proof. In the former case, a variance 
between the allegation and the proof will be fatal if the redundant 
allegations are descriptive of that which is essential. But in the latter 
case, redundancy cannot vitiate, because more is proved than is alleged, 
unless the matter superfluously proved goes to contradict some essential 
part of the allegation. 1 Greenl. Ev. Sec. 67; 1 Stark. Ev. 401. 
    

132 Moby Thesaurus words for "redundancy":
      EDP, abundance, amplitude, avalanche, battology, bedizenment, bit,
      channel, circumambages, circumbendibus, circumlocution,
      cloud of words, communication explosion, communication theory,
      copiousness, data retrieval, data storage, decoding, deluge,
      diffuseness, diffusion, diffusiveness, duplication,
      duplication of effort, effusion, effusiveness,
      electronic data processing, embarras de richesses, embellishment,
      encoding, enough, entropy, excess, expletive, extravagance,
      extravagancy, exuberance, fat, featherbedding, fecundity,
      fertility, filling, flatulence, flood, fluency, formlessness,
      frill, frills, frippery, gingerbread, gush, gushing, inflatedness,
      inflation, information explosion, information theory, inundation,
      landslide, lavishness, logorrhea, luxury, macrology, money to burn,
      more than enough, needlessness, noise, ornamentation, outpour,
      overabundance, overaccumulation, overadornment, overage,
      overbounteousness, overcopiousness, overdose, overflow, overlap,
      overlavishness, overluxuriance, overmeasure, overmuchness,
      overnumerousness, overplentifulness, overplenty, overplus,
      overpopulation, overprofusion, oversufficiency, oversupply,
      padding, palilogy, payroll padding, periphrase, periphrasis,
      plenty, pleonasm, plethora, prodigality, productivity, profuseness,
      profusion, prolificacy, prolificity, prolixity, rampancy, rankness,
      redundance, reiteration, reiterativeness, repetition for effect,
      repetitiveness, roundabout, signal, spate, stammering, stuttering,
      superabundance, superfluity, superfluousness, superflux, surplus,
      surplusage, talkativeness, tautologism, tautology, teemingness,
      tirade, tumidity, turgidity, unnecessariness, verbality,
      verbosity