Re: 15! permutations
- To: mathgroup at smc.vnet.net
- Subject: [mg108654] Re: 15! permutations
- From: Robert Knighten <RLK at SPOOFknighten.org>
- Date: Fri, 26 Mar 2010 05:36:18 -0500 (EST)
- References: <hofgdo$fdg$1@smc.vnet.net>
bn77 <nayantara.bhatnagar at gmail.com> writes: > Hi, > > I'm trying to write a program in mathematica that compares roughly > (15!)^2 / 2 pairs of permutations of length 15. Can mathematica do > this in a reasonable time? Any experience of this sort? > > TIA, > bn77 What does compare mean? How are the permutations available for comparison? You certainly need some way of answering the question for vast blocks at once. (15!)^2 / 2 is about 8.6 x 10^23. If a comparison could be done in 10^(-10) seconds (faster than any currently available PC can do *ANY* compare), then it would still take more than a million years to do that many comparisons one by one. So you need some vast algorithmic improvement over simple comparison of the permutations a pair at a time. -- Bob