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EPOS Evolving Personal to Organizational Knowledge Spaces

Jan-Thies Bähr; Peter Dannenmann; Ludger van Elst; Armin Hust; Andreas Lauer; Heiko Maus; Sven Schwarz
DFKI, DFKI Research Reports (RR), Vol. 04-01, 2004.


We present a simple and intuitive unsound corpus-driven approximation mehtod for turning unification-based grammars (UBGs), such as HPSG, CLE, or PATR-II into context-free grammars (CFGs). The mehtod is unsound in that it does not generate a CFG whose language is a true superset of the language accept by the original unification-based grammar. It is a corpus-driven method in that it relies on a corpus of parsed sentences and generates broader CFGs when given more input samples. Our open approach can be fine-tuned in different directions, allowing us to monotonically come close to the original parse trees by shifting more information onto the context-free symbols. The approach has been fully implemented in JAVA. This report updates and extends the paper presented at the International Colloquium on Grammatical Inference (ICGI 2004) and presents further measurements