"nCk"¶

  my $combinations = nCk($available,$taken);

Returns the binomial coefficient:

 / $available \
 |            |
 \   $taken   /

"enumerate_substitution_maps"¶

 my $enumeration = enumerate_substitution_maps(\%substitutions);

Given a hashref of arrayrefs, interprets it as a map of substitutions. Returns an arrayref of hashrefs, containing all reverse-substitutions.

For example, given:

 {'a' => ['@', '4']}

("'a' can be replaced with either '@' or '4'")

it returns:

  [{'@' => 'a'}, {'4' => 'a'}] ],

("in one case, '@' could have been substituted for 'a'; in the other, '4' could have been substituted for 'a'")

"factorial"¶

  my $fact = factorial($number);

Returns the factorial of the given number.