CFG Domain of Locality

References

(Bangalore & Joshi, 2010) Bangalore, S., & Joshi, A. K. (2010). Supertagging: Using Complex Lexical Descriptions in Natural Language Processing. The MIT Press. ISBN:0262013878 9780262013871
- QUOTE: 1.1 Domain of Locality of CFGs
  In a context-free grammar (CFG) the domain of locality is the one level tree corresponding to a rule in a CFG (figure 1.1). It is easily seen that the arguments of a predicate (for example, the two arguments of likes) are not in the same local domain. The two arguments are distributed over the two rules (two domains of locality)– S → NP VP and V P → V NP. They can be brought together by introducing a rule S → NP V NP. However, then the structure provided by the VP node is lost. We should also note here that not every rule (domain) in the CFG in (figure 1.1) is lexicalized

'(Joshi, 2007) ⇒ Aravind K. Joshi. (2007). “Complexity of Dependencies in Natural Language. Presentation, Vancouver, Feb 22.
- CFG's Domain of Locality (its building blocks) are one level trees. E.g. S -> NP VP; VP -> V NP
TAG's Domain of Locality can extend more than one level e.g. alpha1 ⇒ S (NP') (VP (likes NP'))

(Carrol et al., 1999) ⇒ Carroll, J., Nicolov, N., Shaumyan, O., Smets, M., & Weir, D. (1999, June). Parsing with an extended domain of locality. In: Proceedings of the ninth conference on European chapter of the Association for Computational Linguistics (pp. 217-224). Association for Computational Linguistics. DOI: 10.3115/977035.977065
- ABSTRACT: One of the claimed benefits of Tree Adjoining Grammars is that they have an extended domain of locality (EDOL). We consider how this can be exploited to limit the need for feature structure unification during parsing. We compare two wide-coverage lexicalized grammars of English, LEXSYS and XTAG, finding that the two grammars exploit EDOL in different ways.