Triplestores are Database Management Systems (DBMS) for data modeled using RDF. Unlike Relational Database Management Systems (RDBMS), which store data in relations (or tables) and are queried using SQL, triplestores store RDF triples and are queried using SPARQL. A key feature of many triplestores is the ability to do inference. It is important to note […]
Open World Assumption vs. Closed World Assumption
If you are learning about the Semantic Web, one of the things you will hear is that the Semantic Web assumes the Open World. In this post, I will clarify the distinction between the Open World Assumption and the Closed World Assumption. The Closed World Assumption (CWA) is the assumption that what is not known […]
Introduction to: SKOS
SKOS, which stands for Simple Knowledge Organization System, is a W3C standard, based on other Semantic Web standards (RDF and OWL), that provides a way to represent controlled vocabularies, taxonomies and thesauri. Specifically, SKOS itselfis an OWL ontology and it can be written out in any RDF syntax. Before we dive into SKOS, what is […]
Introduction to: RDF vs XML
There has always been a misconception between the relationship of RDF and XML. The main difference: XML is a syntax while RDF is a data model. RDF has several syntaxes (Turtle, N3, etc) and XML is one of those (known as RDF/XML). Actually, RDF/XML is the only W3C standard syntax for RDF (Currently, there is Last Call […]
Introduction to: SPARQL
SPARQL is the standardized query language for RDF, the same way SQL is the standardized query language for relational databases. If this is the first time you look at SPARQL, but you’re familiar with SQL, you will see some similarities because it shares several keywords such as SELECT, WHERE, etc. It also has new keywords that you have never seen if […]