Hirtle on TRANSLATOR.
David Hirtle is doing graduate work here at the University of New Brunswick, in computer science. The full title of his paper is “TRANSLATOR: a TRANSlator from LAnguage TO Rules.”
Semantic web is still n ot widely used.
– Focus of current development: machine-readable (meta)data
– Problem: only experts can contribute. Need to lower barrier to entry.
Provide a user-friendly format!
– why not English [he really means natural language]?
– “controlled English” avoids ambiguity: it’s formal, but also natural
TRANSLATOR will translate “every student gets a discount of 15 percent” to express [in XML, from what I see] that “student” implies “customer,” etc.
ACE (attempto controlled english):
- looks like English: “every honest student who does not procrastinate receives a good mark and easily passes the course.”
- but actually a formal language, like RDF: a tractable of English – all ACE sentences are English, but not vice versa
- every ACE sentence can be unambiguously translated into logic.
Strategies for handling ambiguity:
- exclude imprecise phrasings (“students hate annoying professors” – do they hate to annoy profs, or do they hate profs who are annoying?)
- interpretation rules (“the student brings a friend who is an alumnus and receives a discount” – who receives the discount? in ace, by default, it’s the student because of a certain rule. If you want it to be the alumnus, you write “…and who receives a discount.”)
How can rules be expressed?
- in natural language, many different forms (everyone is mortal, all humanity is mortal, for each person the person is mortal)
- all above are valid ACE
- further embellishment (negation, relative clauses, etc) [vz: but doesn't that add ambiguity?]
What can’t yet be easily expressed?
- “infix” implication (“the student is happy if there is no class” – solution: TRANSLATOR swaps the condition(s) and conclusion(s) and voila, ACE-acceptable)
- production and reaction rules (involve actions: “if a student is caught cheating then send a report to the registrar” requires the imperative mood, which is not yet in ACE)
Discourse representation structures, and more technical info. Sad, I can’t reproduce his diagrams here. The rules are eventually translated into RuleML, in whose development David is participating.
RuleML:
- goal is interoperable rule markup (XSLT translators to other semantic web languages)
- family of “sublanguages” (modular XML schemas; each represents a well-known rule system; TRANSLATOR uses First-Order Logic sublanguage)
Why use RuleML?
- ease of interchange (XML)
- compatibility with RDF and other languages, as well as W3C’s upcoming Rule Interchange Format
- availability of tools
- wide fariety of features (negation-as-failure, weightings, data types etc.)
Again, work-in-progress. Truly an attempt at getting closer to the semantic web. Formalizing natural language, what a gargantuan task. One critical benefit of TRANSLATOR is that it “allows non-experts to write facts and rules for the semantic web.” When can we play with it?
Now, it appears. Here’s a site for TRANSLATOR, including a Java Web Start demo.