C Semantic Web FAQ The term “rules” in the context of the Semantic Web refers to elements of logic programming and rule based systems bound to Semantic Web data. Rules offer a way to express, for example, constraints on the relationships defined by by RDF, or may be used to discover new, implicit relationships. Various rule systems (production rules, Prolog-like systems, etc) are very different from one another, and it is not possible to define one rule language to encompass them all. A general example may help. The Rule Interchange Format (RIF) Working Group is currently working on a precise definition of this “core” Rule language, on ways to extend this rule language to various variants (production rules, logic programming, etc), to exchange expression of rules among systems, and to define the precise relationships of these rules with OWL ontologies and their usage with RDF triples.
Semantic Web labs des Petites Cases Cette page a vocation à rassembler toutes les expériences concernant les technologies du Web sémantique effectuées dans le cadre de mon blog les petites cases. Ces exemples n'ont aucune prétention autre que pédagogique et démonstratif. Leur pérennité n'est pas garantie. L'ontologie du monde d'Harry Potter Cette ontologie constitue ma première ontologie créée avec le logiciel Protégé. Si vous voulez plus de renseignements sur ces différents exemples, je vous invite à lire les billets correspondants sur mon blog ou à me contacter. FOAF Vocabulary Specification Classes Class: foaf:Agent Agent - An agent (eg. person, group, software or physical artifact). The Agent class is the class of agents; things that do stuff. The Agent class is useful in a few places in FOAF where Person would have been overly specific. [#] [back to top] Class: foaf:Document Document - A document. The Document class represents those things which are, broadly conceived, 'documents'. The Image class is a sub-class of Document, since all images are documents. We do not (currently) distinguish precisely between physical and electronic documents, or between copies of a work and the abstraction those copies embody. [#] [back to top] Class: foaf:Group Group - A class of Agents. The Group class represents a collection of individual agents (and may itself play the role of a Agent, ie. something that can perform actions). This concept is intentionally quite broad, covering informal and ad-hoc groups, long-lived communities, organizational groups within a workplace, etc. Here is an example.
What is the Semantic Web really all about? The Semantic Web is based on the relatively straightforward idea that to be able to integrate (link) data on the Web we must have some mechanism for knowing what relationships hold among the data, and how that relates to some “real world” context. The following is a lot of detail that comes from this simple idea. To answer this question properly, let me start back in the early Web era. Slogan: A little semantics goes a long way key idea 1: SIMPLE key idea 2: URI-based Another student, Jeff Heflin (now a faculty member at Lehigh) started playing with this idea and extended it to include a rule-based reasoner, a Web scraper for extracting SHOE from non-annotated Web sites, a visual query by example system and a bunch of other things. “Linked Data” (or “Web of Data”) – close to the original vision.
Quick Intro to RDF Quick Intro to RDF This is a really brief introduction to Resource Description Framework (RDF). You might also be interested in... For a more detailed look at RDF, see RDF in Depth on this site, which this page was based on. RDF is a method for expressing knowledge in a decentralized world and is the foundation of the Semantic Web, in which computer applications make use of distributed, structured information spread throughout the Web. The Big Picture RDF is a general method to decompose any type of knowledge into small pieces, with some rules about the semantics, or meaning, of those pieces. @prefix : < . The meaning is obvious. If you know XML, here's a brief comparison. But you don't have to use XML. What really sets RDF apart from XML and other things is that RDF is designed to represent knowledge in a distributed world. Consider this second document of RDF: This RDF document defines what it means to be an aunt, in terms of two other relations. So why use RDF?
OpenLink Virtuoso - RDF Views Demo.demo.Orders: Northwind RDF View Definition prefix northwind: < ... create iri class northwind:Order < (in order_id integer not null) . ... alter quad storage virtrdf:DefaultQuadStorage ... from Demo.demo.Customers as customers from Demo.demo.Orders as orders . create virtrdf:NorthwindDemo as graph iri (" { ... northwind:Order (orders.OrderID) a northwind:Order as virtrdf:Order-Order ; northwind:orderDate orders.OrderDate as virtrdf:Order-order_date ; northwind:requiredDate orders.RequiredDate as virtrdf:Order-required_date ; ... northwind:has_customer northwind:Customer (orders.CustomerID) as virtrdf:Order-order_has_customer northwind:has_employee northwind:Employee (orders.EmployeeID) as virtrdf:Order-order_has_employee ; ... } }
How RDF Databases Differ from Other NoSQL Solutions - The Datagraph Blog This started out as an answer at Semantic Overflow on how RDF database systems differ from other currently available NoSQL solutions. I've here expanded the answer somewhat and added some general-audience context. RDF database systems are the only standardized NoSQL solutions available at the moment, being built on a simple, uniform data model and a powerful, declarative query language. These systems offer data portability and toolchain interoperability among the dozens of competing implementations that are available at present, avoiding any need to bet the farm on a particular product or vendor. In case you're not familiar with the term, NoSQL ("Not only SQL") is a loosely-defined umbrella moniker for describing the new generation of non-relational database systems that have sprung up in the last several years. These systems tend to be inherently distributed, schema-less, and horizontally scalable. RDF database systems form the largest subset of this last NoSQL category.
RDF/XML Syntax Specification (Revised) Status of This Document This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at This document is an edited version of the 2004 RDF XML Syntax Specification Recommendation. This document was published by the RDF Working Group as a Recommendation. This document has been reviewed by W3C Members, by software developers, and by other W3C groups and interested parties, and is endorsed by the Director as a W3C Recommendation. This document was produced by a group operating under the 5 February 2004 W3C Patent Policy. 2. This section introduces the RDF/XML syntax, describes how it encodes RDF graphs and explains this with examples. 2.1 Introduction Several RDF/XML examples are given in the following sections building up to complete RDF/XML documents. Example 1 Example 2