Combination
The number of ways of picking 
unordered
outcomes from 
possibilities. Also known as the binomial
coefficient or choice number and read "
choose 
,"
 |
where 
is a factorial
(Uspensky 1937, p. 18). For example, there are 
combinations
of two elements out of the set 
, namely
, 
, 
, 
, 
, and 
. These combinations are known as k-subsets.
The number of combinations 
can be computed
in the Wolfram Language using Binomial[n,
k], and the combinations themselves can be enumerated in the Wolfram
Language using Subsets[Range[n],
k
].
Muir (1960, p. 7) uses the nonstandard notations 
and
.
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