CLP(Flex): Constraint Logic Programming Applied to XML Processing

Abstract

In this paper we present an implementation of a constraint solving module, CLP(Flex), for dealing with unification in an equality theory for terms with flexible arity function symbols. Then we present an application of CLP(Flex) to XML-processing where XML documents are abstracted by terms with flexible arity symbols. This gives a highly declarative model for XML processing yielding a substantial degree of flexibility in programming.

Type-Based Static and Dynamic Website Verification

“…As motivation we present some examples of unification: Note that this non-standard unification is conservative with respect to standard unification: in the last example the first solution corresponds to the use of standard unification. Soundness and completeness of this non-standard unification were proved in [17] and [15].…”

“…Note that ' ' is an unnamed sequence variable which unifies with any sequence. Further details and examples can be found in [2], [15].…”

A Rule-Based Approach to XML Processing and Web Reasoning

“…Besides the already mentioned Xcerpt, the languages like Elog [3], XPathLog [21], and XCentric [11,12] belong to this category. The latter one, like PρLog, represents XML data as an unranked Prolog term and uses sequence matching with regular types for querying.…”

Sequence Unification Through Currying

“…In the previous example, substitution for variable X V1 in solutions ϕ 3 and ϕ 4 are not "well-typed", i.e. they are not the curry form of any sequence of unranked terms.…”

“…The ISO standard proposal for Common Logic [6] has notation for sequence variables (called there sequence markers). Recently there have been developments in XML querying and transformation that model XML documents with terms over an unranked signature and use sequence matching and unification techniques [15] for querying, transforming, and verifying them [4,5]. Obviously, we can not give an exhaustive overview of all the applications here.…”