Permutations.

*To*: mathgroup at smc.vnet.net*Subject*: [mg14771] Permutations.*From*: "Alan W.Hopper" <awhopper at hermes.net.au>*Date*: Sat, 14 Nov 1998 03:08:02 -0500*Sender*: owner-wri-mathgroup at wolfram.com

Greetings, For the combinations of n objects taken k at a time, (where order counts and there is no duplication), the function KSubsets is the one to use. e.g. In[1]:= <<DiscreteMath`Combinatorica` In[2]:= Table[KSubsets[{a,b,c,d}, k], {k, 4}] Out[3]= {{{a}, {b}, {c}, {d}}, {{a,b}, {a,c}, {b,c}, {b,d}, {c,d}}, {{a,b,c}, {a,b,d}, {a,c,d}, {b,c,d}}, {{a,b,c,d}}} But likewise in wanting to find all the permutation subsets (with no duplication and order not counting), of a numerical or symbolic list, there does not seem to be a function anywhere (including the packages), to achieve this goal. (By n!/(n-k)!, there will be be; 4, 12, 24, 24 permutations taken k = 1, 2, 3, 4 at a time, for a 4 element list). The built-in function Permutations and also LexicographicPermutations (from Combinatorica) do not take a second argument, as KSubsets does, and so only the (n, k=n) permutations (24 in the example ) can be found. I would appreciate some assistance to find a way to generate all of the permutation subsets, in List, Table or Column form. Alan W.Hopper awhopper at hermes.net.au

**Follow-Ups**:**Re: Permutations.***From:*Jurgen Tischer <jtischer@col2.telecom.com.co>