A Question about Combinatorica

*To*: mathgroup at smc.vnet.net*Subject*: [mg102627] A Question about Combinatorica*From*: Marwa Abd El-Wahaab <m.a.elwahaab at gmail.com>*Date*: Mon, 17 Aug 2009 04:04:09 -0400 (EDT)

Dear Sir, I have a question about having five letters like {A, B, C, D, E}. In order to get all possibilities, we have 5! possible cases like ABCDE, EABCD,.......etc The number of these possibilities are 120. How and why this number becomes 60 by dividing by 2 ? What are 60 possibilities & how extract them from 120? I used this function to get 120: MinimumChangePermutations[{A,B,C,D,E}] What should I do after this to get 60? Thanks too much I really need your help *Marwa Ali Abd El Wahaab* *Teaching Assistant* Faculty of Engineering Mansoura University

**Follow-Ups**:**Re: A Question about Combinatorica***From:*Murray Eisenberg <murray@math.umass.edu>

**Re: A Question about Combinatorica***From:*Andrzej Kozlowski <akoz@mimuw.edu.pl>