Describing Syntax with Star-Free Regular Expressions

Syntactic constraints in Koskenniemi’s Finite-State Intersection Grammar (FSIG) are logically less complex than their formalism (Koskenniemi et al., 1992) would suggest: It turns out that although the constraints in Voutilainen’s (1994) FSIG description of English make use of several extensions to regular expressions, the description as a whole reduces to a finite combination of union, complement and concatenation. This is an essential improvement to the descriptive complexity of ENGFSIG. The result opens a door for further analysis of logical properties and possible optimizations in the FSIG descriptions. The proof contains a new formula for compiling Koskenniemi’s restriction operation without any marker symbols.

• Type: Conference
• Year: 2003
• Where: EACL
• Authors: Anssi Yli-Jyrä
• Keywords: EACL 2003, Finite-State Intersection Grammar, Fsig Descriptions, Natural Language Processing, Syntactic Constraints