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. However, it is possible to define a “core” that is essentially understood by all rule systems. This core is based on restricted kind of rule, called a “Horn” rule, which (like most rules) has the form “if conditions then consequence”, but it places certain restrictions on the kinds of conditions and consequences that can be used.
A general example may help. While integrating data coming from different sources, the data may include references to persons, their name, homepage, email addresses, etc. Graphviz - Graph Visualization Software. IsaViz Overview. News IsaViz and Java 1.6 (2007-10-21) IsaViz 2.x is not compatible with Java 1.6 or later. It is recommended to download IsaViz 3.0 which does work with any version of Java. An alpha release is available (see Download section), which should be as stable as IsaViz 2.1 except for the new, still under development, Fresnel and FSL features. IsaViz and GraphViz (2007-05-23) IsaViz 2.x is not compatible with GraphViz 2.10 or later. It is thus recommended to use GraphViz 2.8 or earlier with IsaViz 2.x. Several bugs have been fixed in the FSL engines for Jena, Sesame and the visual FSL debugger embedded in IsaViz. Fresnel in IsaViz (2006-05-19) IsaViz 3.0 now supports Fresnel lenses and several elements of the Core Format Vocabulary.
FSL for Sesame 2-alpha-3 (2006-04-25) The FSL engine for Sesame 2 now works with version 2alpha3 instead of version 2alpha1. FSL for Sesame 1.2.2 (2005-12-06) Java FSL Documentation available (2005-11-18) FSL for Sesame 2.0 (2005-11-15) Screenshots Download Plug-Ins. 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. While I’m going to do some potentially boring personal history, I’ll note the key ideas as I go along.
Circa 1995, my research group began playing with an idea (first proposed by my then student Sean Luke now a faculty member at GMU) that if web markup (it was all HTML back then) contained some machine readable “hints” to the computer, then we could do a better job of Web tasks like search, query, and faceted browsing. “Linked Data” (or “Web of Data”) – close to the original vision. Web 3.0. Working with RDF with Perl. Semantic technologies.