Team, Visitors, External Collaborators
Overall Objectives
Research Program
Application Domains
New Software and Platforms
New Results
Partnerships and Cooperations
XML PDF e-pub
PDF e-Pub

Section: New Results

Backward Type Inference for XML Queries

Although XQuery is a statically typed, functional query language for XML data, some of its features such as upward and horizontal XPath axes are typed imprecisely. The main reason is that while the XQuery data model allows to navigate upwards and between siblings from a given XML node, the type model, e.g., regular tree types, can only describe the subtree structure of the given node. In 2015, Giuseppe Castagna and our team independently proposed a precise forward type inference system for XQuery using an extended type language that can describe not only a given XML node but also its context. Recently, as a complementary method to such forward type inference systems, we propose an enhanced backward type inference system for XQuery, based on an extended type language. Results include an exact type system for XPath axes and a sound type system for XQuery expressions.