Permutation/Ordered Selection/Examples/2 from 4

Example of Permutations

There are $12$ permutations of $4$ objects taken $2$ at a time:

$a \, b \quad a \, c \quad a \, d \quad b \, c \quad b \, d \quad c \, d$

and then the same reversed:

$b \, a \quad c \, a \quad d \, a \quad c \, b \quad d \, b \quad d \, c$


Sources

  • 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): permutation: 1.
  • 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): permutation: 1.
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