METHOD AND APPARATUS FOR EXPANDING SIMILAR CHARACTER STRINGS

A table of derivation elements and a state-transition table indicating applicable strings of derivation types are produced according to pronunciation expanding rules in a similar character string expanding apparatus. Each of the derivation elements is composed of a derived sound derived from a key sound placed at a key position of a question pronunciation character string, a sound position of the derived sound in each of character strings expanded from the question pronunciation character string and one or more derivation types indicating how the derived sound placed at the sound position is derived from the key sound placed at the key position. In a character string retrieving apparatus, strings of derivation types are produced one by one by arranging derivation types of the table of derivation elements in order of the sound position, and it is judged whether or not each of the strings of derivation types agrees with one of the applicable strings to judge whether or not each of the strings of derivation types satisfies the pronunciation expanding rules. Thereafter, trademark numbers corresponding to the strings of derivation types satisfying the pronunciation expanding rules are retrieved. Therefore, because any character strings similar in pronunciation to the question pronunciation character string is not directly used, the trademark numbers indicating trademarks similar to the question pronunciation character string can be retrieved at high speed.