English Dictionary: Permutation | by the DICT Development Group |
3 results for Permutation | |
From WordNet (r) 3.0 (2006) [wn]: | |
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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 The Free On-line Dictionary of Computing (15Feb98) [foldoc]: | |
permutation 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 you can find an inverse permutation that reverses the action of any given permutation. 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. 2. A {bijection} for which the {domain} and {range} are the same set and so f(f'(x)) = f'(f(x)) = x. (2001-05-10) |