Re: Binomial Coefficients

*To*: mathgroup at smc.vnet.net*Subject*: [mg5812] Re: [mg5782] Binomial Coefficients*From*: Robert Pratt <rpratt at math.unc.edu>*Date*: Wed, 22 Jan 1997 00:44:16 -0500*Sender*: owner-wri-mathgroup at wolfram.com

Use the KSubsets command found in the standard package DiscreteMath`Combinatorica`: In[1]:= Needs["DiscreteMath`Combinatorica`"] In[2]:= ?KSubsets KSubsets[l,k] returns all subsets of set l containing exactly k elements, ordered lexicographically. In[2]:= KSubsets[{1,2,3,4,5},2] Out[2]= {{1, 2}, {1, 3}, {1, 4}, {1, 5}, {2, 3}, {2, 4}, {2, 5}, {3, 4}, > {3, 5}, {4, 5}} Rob Pratt Department of Mathematics The University of North Carolina at Chapel Hill CB# 3250, 331 Phillips Hall Chapel Hill, NC 27599-3250 rpratt at math.unc.edu On Sat, 18 Jan 1997, H. Thompson wrote: > I understand about k-permutations and 'n choose k', and while i can > mathematically determine the max possible combinations of say a 5 character > string > > > n! / [k! (n-k)!] > I have yet to successfully debug my algorithm so it produces all of the > calculated permutations. > > > Any help would be greatly appreciated. > > > hrt > >