Semi-incremental Recognition of Online Handwritten Mathematical Expressions

This paper presents a semi-incremental recognition method for online handwritten mathematical expressions (MEs). The method reduces the waiting time after an ME is written until the result of recognition is output. Our method has two main processes, one is to process the latest stroke, the other is to find and correct wrong recognitions in the strokes up to the latest stroke. In the first process, the segmentation, recognition and Cocke-Younger-Kasami (CYK) algorithm are only executed for the latest stroke. In the second process, all the previous segmentations are updated if they are significantly changed after the latest stroke is input, and then, all the symbols related to the updated segmentations will be updated with their recognition scores. These changes are reflected into the CYK table. In addition, the waiting time is further reduced by employing multi-thread processes. Experiments on our data set show the effectiveness of this semi-incremental method which not only has higher recognition rate than our previous pure-incremental method but also keeps the waiting time unnoticeable.