Existing commercial formula entry systems are either command-string or template based. While these are reasonably powerful and not too hard to use, they do not provide easy entry and editing of formulae. The ideal input method is via a pen-based interface, which means that the formula has to be parsed either as it is entered, or once it is complete.
Each of the existing methods for parsing handwritten or typeset
formulae have their own strengths and weaknesses with respect to the
various issues of formula processing. Of the approaches presented
here, a formula processor using either a stochastic grammar or graph
rewriting appears to be the best choice for parsing handwritten
formulae.