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permutation |
3 definitions found From Webster's Revised Unabridged Dictionary (1913) [web1913]: Permutation \Per`mu*ta"tion\, n. [L. permutatio: cf F. permutation. See {Permute}.] 1. The act of permuting; exchange of the thing for another; mutual transference; interchange. The violent convulsions and permutations that have been made in property. --Burke. 2. (Math.) a The arrangement of any determinate number of things as units, objects, letters, etc., in all possible orders one after the other -- called also {alternation}. Cf {Combination}, n., 4. b Any one of such possible arrangements. 3. (Law) Barter; exchange. {Permutation lock}, a lock in which the parts can be transposed or shifted, so as to require different arrangements of the tumblers on different occasions of unlocking. From WordNet r 1.6 [wn]: permutation n 1: an event in which one thing is substituted for another [syn: {substitution}, {transposition}, {replacement}, {switch}] 2: the act of changing the arrangement of a given number of elements 3: complete change in character or condition: "the permutations...taking place in the physical world"- Henry Miller 4: act of changing the lineal order of objects in a group From The Free On-line Dictionary of Computing (13 Mar 01) [foldoc]: permutationAn ordering of a certain number of elements of a given set For instance, the permutations of (1,2,3) are (1,2,3) (2,3,1) (3,1,2) (3,2,1) (1,3,2) (2,1,3). Permutations form one of the canonical examples of a "{group}" - they can be composed and that you can find an inverse permutation that reverses the action of any given permutation. A permutation is a {bijection}. The number of permutations of r things taken from a set of n is n P r = n! / (n-r)! where "n P r" is usually written with n and r as subscripts and n! is the {factorial} of n. What the football pools call a permutation" is not a permutation but a {combination} - the order does not matter. (1995-04-10)
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