XCentric: Constraint based XML Processing
Jorge Coelho (Instituto Superior de Engenharia do Porto & LIACC)
Mário Florido (University of Porto, DCC-FC & LIACC)

Here we present the logic-programming language XCentric, discuss design issues, and show its adequacy for XML processing. Distinctive features of XCentric are a powerful unification algorithm for terms with functors of arbitrary arity (which correspond closely to XML documents) and a rich type language that uses operators such as repetition, alternation, etc, as types allowing a compact representation of terms with functors with an arbitrary number of arguments (closely related to standard type languages for XML). This new form of unification together with an appropriate use of types yields a substantial degree of flexibility in programming.

XML and Databases, XML Query Languages, Document Processing using XML