Error-repair parsing schemata

Robustness, the ability to analyze any input regardless of its grammaticality, is a desirable property for any system dealing with unrestricted natural language text. Error-repair parsing approaches achieve robustness by considering ungrammatical sentences as corrupted versions of valid sentences. In this article we present a deductive formalism, based on Sikkel’s parsing schemata, that can be used to define and relate error-repair parsers and study their formal properties, such as correctness. This formalism allows us to define a general transformation technique to automatically obtain robust, error-repair parsers from standard non-robust parsers. If our method is applied to a correct parsing schema verifying certain conditions, the resulting error-repair parsing schema is guaranteed to be correct. The required conditions are weak enough to be fulfilled by a wide variety of popular parsers used in natural language processing, such as CYK, Earley and Left-Corner.