Gennaro Costagliola Vincenzo Deufemia Michele Risi Using Grammar-Based Recognizers for Symbol Completion in Diagrammatic Sketches. 1078-1082 2007 conf/icdar/2007 ICDAR http://doi.ieeecomputersociety.org/10.1109/ICDAR.2007.259 db/conf/icdar/icdar2007.html#CostagliolaDR07