Syntactic Recovery and Spelling Correction of Ill-formed Sentences

This paper describes syntactic repair and spelling correction of ill-formed sentences within a context-free grammar using non-static filtering, of ill-formed sentences which violate subjectverb agreement or premodifier-noun agreement. The system described here provides recovery of local trees, reconstruction of the sentence, and spelling correction of detected typographical errors. It also produces a report on the repair that has been carried out. The system includes generalised problem-solving strategies for detecting and correcting several types of syntactic and typographical errors, and also includes heuristics. The paper focuses on a system for the integration of lexical and syntactic recovery of ill-formed sentences at the local tree and the final goal (sentence) level. The system is based on a chart parser and employs a mixed top-down/bottom-up strategy together with left-to-right and rightto-left parsing. The implementation is composed of two chart parsers: a well-formed sentence chart parser (WFSCP) and an ill-formed sentence chart parser (IFSCP), and a spelling correction algorithm based on dictionary lookup.