W3C and the Semantic Web
by Jos De Roo
W3C Semantic Web Activity
- A key activity of the World Wide Web Consortium W3C (inventor T.Berners-Lee)
- develops interoperable technologies (specifications, guidelines, software and tools)
- to lead the web to its full potential
- as a forum for information, commerce, communication and collective understanding
- The semantic web
- is an extension of the current one
- focuses on the meaningful content of web pages
- creates an environment where software agents roaming from page to page carry out sophisticated
tasks for users
- becomes a place where data can be shared and processed by automated tools as well as by people
W3C SW Activity - Goals
- Design of technologies that support machine facilitated global knowledge
- Making it cost-effective for people to record their knowledge.
- Focus on machine consumption
|"The bane of my existence is doing things that I
know the computer could do for me."
-- Dan Connolly, The XML Revolution
W3C SW Activity - Structure
W3C SW Activity - Approach to Deployment
A lot of hard work - and a bit of luck
- Foster an environment for effective cooperation and collaboration
- Establish guiding architectural principles
- Facilitate the design of enabling standards and technologies
- Understand policy implications
- Focus on short term deployment
- Eye toward longer term research issues
- URI->Resource static mapping
- Creates navigable "space"
- Shared space = new genre of communication
- Self-describing documents
- URIs as identifiers not recipes
- Machine processable
- not natural language, human inference
- For data: what you can do with it
- For the future: conversion
SW Principles 1: Everything identifiable is on SW
- All resources have identity
- People, places, and things in the physical world have online
representations identified by URI's.
- URI's support participation, effective integration and are contextualized
SW Principles 2: Partial information is tolerated
- The current Web is unbounded.
- Sacrifices link integrity for scalability.
- The Semantic Web it unbounded.
- Anyone can say anything about anything.
- There will always be more to discover.
SW Principles 3: There is no need for absolute truth
- All statements on the Web occur in some context.
- Applications need this context in order to evaluate the trustworthiness of
- The machinery of the SW does not assert that all statements found on the
Web are "true".
- Truth - or more pragmatically, trustworthiness - is evaluated by each
application that processes the information on the Web.
SW Principles 4: Evolution is supported
- Allow effective combination of the independent work of diverse
- Support the ability to add new information without insisting that the old
- Provide communities the ability to resolve ambiguities and clarify
- Use descriptive conventions that can expand as human understanding
SW Principles 5: Minimalist design
- Make the simple things simple, and the complex things possible.
- Enable simple applications now that plan for future complexity (eg. Dublin
Core, RSS, MusicBrainz)
- Standardize no more than is necessary.
- Result more than the sum of the parts
Enabling Standards & Technologies - Layer Cake
RDF Core Working Group (RDFCore)
- RDF provides a common framework for representing metadata across many
- Clarifies and improves RDF's abstract model and XML syntax according to
- Completes the RDF vocabulary description in the RDF Schema Candidate
- Explains the relationships between the basic components of RDF (Model,
Syntax, Schema) and the larger XML family of recommendations.
- Minimalist model - (thing), Class, Property
- Subproperty, Subclass
- Domain & Range
- Comments & labels
Very wide interoperability
Web Ontology Working Group (WebOnt)
- Standardize means for defining ontologies that can be used on the Web.
- Builds on RDF Schema (classes and subclasses, properties and
- Extends these constructs to allow more complex relationships between
- limit the properties of classes with respect to number and type
- means to infer that items with various properties are members of a
- a well-defined model for property inheritance
- Input from the DAML+OIL work supported
by DARPA's DAML Initiative
- More metainformation, such as
- Transitive property
- Unique, Unambiguous, Cardinality, etc
- Ontology community exists- DL, OIL, SHOE, etc. etc.
- Huge extra usage for extra functionality
- Not Turing complete
Wide interoperability & interconversion
- Universal language for monotonic logic
- Any rule system can export, generally cannot import
- No one standard engine - inference capabilities differ
- Many engines exist (SQL to KIF, Cycl, etc)
- Any system can validate proofs
SW Public Forums
- Semantic Web / RDF Interest
- Dan Brickley mailto:email@example.com
- a forum for W3C Members and non-Members to discuss innovative
applications of RDF and the Semantic Web.
- RDF Logic
- detailed technical discussion of all approaches to the use of classical
logic on the Web for the representation of data such as inference rules,
ontologies, and complex schemata.
- RDF Calendar
- public forum for discussion of RDF-based calendar and group scheduling
- public forum for discussion of RDF-based annotation and collaboration
SW Advanced Development - Goals
- Explore pre-competitive, prototype ideas
- Venue for liaison with research community;
- Inform, be informed, nudge, be nudged
- Testbed for early implementations of Working Drafts
- Collaborative development environment for the Team and Members to explore
- Stimulate the development of more Semantic Web infrastructure components
SW Advanced Development - Areas
- Developer's Tools
- Resource Description
- Annotation, Collaboration, and Web of Trust
- Access Control Rules, Logic and Proof
- Calendaring and Scheduling
- Work-flow and Dependency Tracking
- Transformation and Extraction Utilities
- Integration with XML infrastructure
Examples of Running Code
Closed World Machine
Euler Proof Mechanism
- research component to support logic based proofs.
- Prolog unification (substitutions, unifiers) & resolution algorithm & backtracking
- Euler path detection
- "existential introduction rule" generation (w.r.t. RDF bNodes)
- unification of variable predicates
- use as much as possible from DanC's and TimBL's SWAP
- W3C Semantic Web efforts build common infrastructure
- First supports simple and then more complex systems
- Offers optimal reuse of data in networked environment
- More formal understanding of these relationships however are still