XTFDs: FDs for XML Documents

摘要

Functional Dependencies (FDs) are a common constraint for many applications. Specifying FDs in XML documents,rnhowever, is difficult because XML documents do not have uniform structures. We introduce XML Template FunctionalrnDependencies (XTFDs), which can specify FDs in XML documents, in this paper. Previously, we defined XTFDs in termsrnof variables only (Mok, 2005). In this paper, we extend our previous work by incorporating Xpath expressions. Byrnincorporating Xpath expressions, we can express more FDs in XML documents. Since XTFDs are based on simple conceptsrnlike variables, functions, and Xpath expressions, XTFDs are more intuitive than other proposals of the same purpose in thernliterature. We are currently comparing XTFDs with the approaches in Arenas & Libkin (2004); Vincent et al. (2004). Arnpreliminary comparison shows that XTFDs improve the approaches in Arenas & Libkin (2004); Vincent et al. (2004) ifrnrecursive structures, mixed content and optional attributes are allowed.