Toward a Principle-Based Parser
Parser design lags behind linguistic theory. While modern transformational grammar has largely abandoned complex, language-specific rule systems in favor of modular subsystems of principles and parameters, the rule systems that underlie existing natural-language parsers are still large, detailed, and complicated. The shift to modular theories in linguistics took place because of the scientific disadvantages of such rule systems. Those scientific ills translate into engineering maladies that make building natural-language systems difficult. The cure for these problems should be the same in parser design as it was in linguistic theory. The shift to modular theories of syntax should be replicated in parsing practice; a parser should base its actions on interacting modules of principles and parameters rather than a complex, monolithic rule system. If it can be successfully carried out, the shift will make it easier to build natural-language systems because it will shorten and simplify the language descriptions that are needed for parsing. It will also allow parser design to track new developments in linguistic theory.