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combinat::choose -- Computes all k-subsets of a given set

Introduction

combinat::choose(set,k) computes all k-subsets of the given set set

combinat::choose(N,k) computes all k-subsets of the set setN where setN = 1,2,...,N.

Call(s)

combinat::choose(set,k)
combinat::choose(N,k)

Parameters

set - a set of domain type DOM_SET
k - a nonnegative integer
N - a nonnegative integer

Returns

combinat::choose returns an expression sequence, consisting of the computed subsets.

Example 1

Compute all the subsets of a,b,c,d,e containing 3 elements

>> combinat::choose({a,b,c,d,e},3) 
      {c, d, e}, {b, d, e}, {a, d, e}, {b, c, e}, {a, c, e},
      
         {a, b, e}, {b, c, d}, {a, c, d}, {a, b, d}, {a, b, c}

Example 2

Compute all the subsets of 1,2,3 containing 2 elements

>> combinat::choose(3,2) 
                          {2, 3}, {1, 3}, {1, 2}

Example 3

It's not a good idea to compute the subsets containing -1 element

>> combinat::choose({a,3},-1) 
      Error: Second argument must be a nonnegative integer [combinat\
      ::choose]

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