Patent ID: 7181068

Claim:
A mathematical expression recognizing device comprising: a character recognition unit configured to recognize characters in a document image containing a text and a mathematical expression; a first dictionary configured to store a pair of evaluation scores for each type of word that can be identified by means of normal expression, a first one of the pair of evaluation scores giving the probability of belonging to the text and a second one of the pair of evaluation scores giving the probability of belonging to the mathematical expression; an evaluation unit configured to obtain from the first dictionary the first and second evaluation scores showing the probability of belonging to the text and that of belonging to the mathematical expression for each of the words included in the characters recognized by the character recognition unit with reference to the first dictionary; and a mathematical expression detecting unit configured to search for an optimal path connecting words by selecting one of the text and the mathematical expression based on a formative grammar and the first and second evaluation scores showing the possibility of belonging to the text and that of belonging to the mathematical expression for each of the words, the optimal path having the largest sum of evaluation scores given to a word, thereby detecting characters belonging to the mathematical expression.