       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:= Needs["DiscreteMath`Combinatorica`"]

In:= ?KSubsets
KSubsets[l,k] returns all subsets of set l containing exactly k elements,
ordered lexicographically.

In:= KSubsets[{1,2,3,4,5},2]

Out= {{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
>
>

```

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