An efficient syntactic approach to structural analysis of on-line handwritten mathematical expressions

Machine recognition of mathematical expressions is not trivial even when all the individual characters and symbols in an expression can be recognized correctly. In this paper, we propose to use Definite Clause Grammar (DCG) as a formalism to define a set of replacement rules for parsing mathematical expressions. With DCG, we are not only able to define the replacement rules concisely, but their definitions are also in a readily executable form. However, a DCG parser is potentially inefficient due to its frequent use of backtracking. Thus we propose some methods here to increase the efficiency of the parsing process. Experiments done on some commonly seen mathematical expressions show that our proposed methods can achieve quite satisfactory speedup, making mathematical expression recognition more feasible for real-world applications.