1. A method for use in handwriting recognition in computer algebra, comprising: receiving handwriting input from a user via a handwriting input device associated with a graphical user interface of an application program, the handwriting input containing a mathematical expression; at a recognizer configured to communicate with the application program via an application programming interface, processing the handwriting input to recognize a plurality of candidates; at the recognizer, ranking the plurality of candidates to form initial candidate data; at an application program, scanning the plurality of candidates for segments that match application-level criteria; at the application program, adjusting a rank of one or more of the plurality of candidates that match the application-level criteria, to form a processed candidate list; and displaying the processed candidate list including the plurality of candidates with rank adjusted based on application-level criteria, via the graphical user interface.