Local Ambiguity Packing and Discontinuity in German

We report on recent advances in HPSG parsing of German with local ambiguity packing (Oepen and Carroll, 2000), achieving a speed-up factor of 2 on a balanced test-suite. In contrast to earlier studies carried out for English using the same packing algorithm, we show that restricting semantic features only is insufficient for achieving acceptable runtime performance with a German HPSG grammar. In a series of experiments relating to the three different types of discontinuities in German (head movement, extraction, extraposition), we examine the effects of restrictor choice, ultimately showing that extraction and head movement require partial restriction of the respective features encoding the dependency, whereas full restriction gives best results for extraposition.