This paper compares Marcus' parser, PARSIFAL with Woods' Augmented Transition Network (ATN) parser. In particular, the paper examines the two parsers in light of Marcus' Determinism Hypothesis. An overview of each parser is presented. Following that, the Determinism Hypothesis is examined in detail. A method for transforming the PARSIFAL grammar rules into the ATN formalism is outlined. This transformation shows some of the fundamental differences between PARSIFAL and ATN parsers, and the nature of the hypotheses used in PARSIFAL. Finally, the principle of least commitment is proposed as an alternative to the Determinism Hypothesis.
