54. The invention set forth in claim 52 wherein three classes of subproblems are defined based on the following possibilities, (a) that the first character of each input string is correct, (b) that the first character of each input string is an extraneous character which should be discarded, and (c) that each input string is missing a character that should be inserted before the first character of that input string.
55. The invention set forth in claim 54 wherein said first class (a) of subproblems is investigated by a method comprising the steps of identifying the portion of the directory in which the first character of the input string is matched by the first character of the directory strings, said portion to be known as the matching portion of the directory, and searching a directory obtained from the matching portion by removing the first character from each string in said matching portion for a character string closely resembling the input string with its first character removed.