Patent US 4,882,703

A procedure for finding words within words as implemented on a programmable digital computer first alphabetizes all letters in the given word then computes permutations of the alphabetized letters and compares them to a special dictionary created so that when a match is found in it this refers to dictionary words that are anagrams of the permutation of letters. The special dictionary is created by first preprocessing each word into an alphabetic concatenation of the letters in it, then appending the word to this anagram. This list is separated by word length, alphabetized and stored in random files for fast table look up. A finger index is created and used in the procedure to further speed execution of the process.