With negative mappings, null maps to all:e, while each proper noun maps to its proper predicate minus all:e. There is a lot of work in semantic parsing that tackles the GeoQuery dataset (Zelle and Mooney, 1996;Zettlemoyer and Collins, 2005;Wong and Mooney, 2007;Kwiatkowski et al., 2010;Liang et al., 2011), and the state-of-the-art is 91.1% precision and recall (Liang et al., 2011).
none of these methods can guarantee 100% precision, and they perform more feature engineering, so these numbers are not quite comparable.