The IsDerangement( s, t ) command returns the value true if the string s is a derangement of the string t, and returns the value false otherwise. The strings s and t are derangements of one another if they differ at the $i$th position, for each index $i$.

Note that no string with a repeated character can be a derangement of another string; therefore, each of the strings s and t must be permutations.  See StringTools[IsPermutation].

All of the StringTools package commands treat strings as (null-terminated) sequences of $8$-bit (ASCII) characters.  Thus, there is no support for multibyte character encodings, such as unicode encodings.

$\mathrm{with}\left(\mathrm{StringTools}\right)\:$

$\mathrm{IsDerangement}\left(''foo''\,''oof''\right)$

$\mathrm{false}$

$\mathrm{IsDerangement}\left(''edit''\,''tide''\right)$

$\mathrm{true}$

The StringTools[IsDerangement] command was introduced in Maple 18.

For more information on Maple 18 changes, see Updates in Maple 18.