Introduction to E4X

Jon Udell posts a nice intro to E4X (running on Rhino).

A series of code snippets gives you a taste of how E4X can be used to manipulate XML.

Description Logics in Literate Haskell

Experiments from Graham Klyne:

This file is my attempt to better understand the structure and uses
of Description Logic (DL) languages for knowledge reresentation and inference, with the ultimate aim of better understanding the capabilities and limitations of the Semantic Web ontology language OWL, whose design draws much from Description Logic languages.

See also rdfweb-dev post, "Haskell vs. Ada vs. C++ vs. Awk vs. ..., An Experiment in Software Prototyping Productivity" (PS format)

SAT 3 Proof with E Prover via OWL

An interesting little Semantic Web-related development reported by Jos De Roo (creator of the Java/C# Euler inference engine). He's got the E Prover (an equational theorem prover for clausal logic), to find a proof for the OWL (Web Ontology Language) test case "inconsistent502" (RDF, variations), which is a Description Logic encoding of one of the classic SAT 3 problems.

"Your" RDF Query Language

Kendall Clark of the Data Access Working Group (part of the W3C's Semantic Web initiative) has posted regarding their work on a query language and access protocol for RDF. The DAWG has recently released the 2nd draft of its Use Cases and Requirements and is looking for community input. Their initial query language design, BRQL, looks SQL-like but is designed to operate on graphs/sets of triples.

Type-Based Optimization for Regular Patterns

Type-Based Optimization for Regular Patterns, by Michael Y. Levin and Benjamin C. Pierce. WWW Workshop on High-Performance XML Processing, May 2004.

We describe work in progress on a compilation method based on matching automata, a form of tree automata specialized for pattern compilation, in which we use the schema of the value owing into a pattern matching expression to generate more efficient target code.

A set of slides is also available.

XsRQL (and other RQLs)

The RDF Data Access Working Group is busy doing a survey of query languages and access techniques that have been used with RDF. Many resemble SQL in syntax, despite operating on a graph. Amongst the WG's Design Evaluations Links there's a recent submission of a different style from Howard Katz : XQuery-style RDF Query Language (XsRQL), which actually looks very procedural (like XQuery).

Tim Bray: Languages Cost

Tim Bray writes about custom document schemas:

HTML isn’t unusual. Documents are hard to design, and general frameworks for families of documents are even harder. The conventional wisdom back in the day was that to get yourself a good DTD designed, you were looking at several tens of thousands of dollars.

Then, once you’ve got your language designed, you start the hard work on the software. Frameworks like XSLT help, but no significant language comes without a significant cost in software design.

As I've often said here ("here" in the general sense that is), XML vocabulary design is language design. Language design is hard. Hard things often cost.

However, Tim wants us to believe that one language is enough. I really hope he is wrong about that...

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