  Syntactic natural language parsers have shown themselves to be inadequate for
processing highly-ambiguous large-vocabulary text, as is evidenced by their
poor performance on domains like the Wall Street Journal, and by the movement
away from parsing-based approaches to text-processing in general. In this
paper, I describe SPATTER, a statistical parser based on decision-tree learning
techniques which constructs a complete parse for every sentence and achieves
accuracy rates far better than any published result. This work is based on the
following premises: (1) grammars are too complex and detailed to develop
manually for most interesting domains; (2) parsing models must rely heavily on
lexical and contextual information to analyze sentences accurately; and (3)
existing {$n$}-gram modeling techniques are inadequate for parsing models. In
experiments comparing SPATTER with IBM's computer manuals parser, SPATTER
significantly outperforms the grammar-based parser. Evaluating SPATTER against
the Penn Treebank Wall Street Journal corpus using the PARSEVAL measures,
SPATTER achieves 86\% precision, 86\% recall, and 1.3 crossing brackets per
sentence for sentences of 40 words or less, and 91\% precision, 90\% recall,
and 0.5 crossing brackets for sentences between 10 and 20 words in length.
