a) If you are generating a sequence of permutations by using swaps, successive permutations will be odd and even. b) If you know the number of loops in a permutation, it's easy to calculate odd or even-ness. c) vintage: I know the MIT crowd were generating permutations using swaps c. 1966; Gosper might be able to establish an earlier date. Rich
* Schroeppel, Richard <rschroe@sandia.gov> [Dec 18. 2006 14:06]:
[...]
c) vintage: I know the MIT crowd were generating permutations using swaps c. 1966; Gosper might be able to establish an earlier date.
Earlier references might be found (I didn't check) in Robert Sedgewick: Permutation Generation Methods ACM Computing Surveys (CSUR), vol.9, no.2, pp.137-164, June-1977. Online at http://www.princeton.edu/~rblee/ELE572Papers/
Rich
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Quoting "Schroeppel, Richard" <rschroe@sandia.gov>:
c) vintage: I know the MIT crowd were generating permutations using swaps c. 1966; Gosper might be able to establish an earlier date.
Wasn't the Reverend Young doing this back in the twenties? - hvm ------------------------------------------------- www.correo.unam.mx UNAMonos Comunicándonos
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Joerg Arndt -
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Schroeppel, Richard