Unit 4: Semantic web
Describe the three different syntatic categories of ontology
1. Entities - such as classes, properties and individuals, are identified by internationalized resource identifiers 2. Expressions - represent complex notions in the domain being described. For example, a class expression describes a set of individuals in terms of the restrictions on the individuals characteristics 3. Axioms - are statements that are asserted to be true in the domain being described
What's OWL?
A component of the semantic web activity. This effort aims to make web resources more readily accessible to automated processes by adding information about resources that describe or provide web content. As the semantic web is inherently distributed, OWL must allow for information to be gathered from distributed sources. Which is partly done by allowing ontologies to be related, including explicity importing information from other ontologies
What's Protege?
An open source online ontology editor
Whats ontology?
Easily described as common, shared understanding of a domain. Consists of a formal (machine-readable) explicit specification (concepts, properties, relations, functions, constraints, axioms) of a shared (consensual knowledge) conceptualization (abstract model and simplified view of some phenomenon in the world that we want to represent
What's RDF schema?
Language for describing/ modeling RDF vocabularies and a simple way to create ontologies
What's RDF?
Resource description framework. A data model of the semantic web whom's descriptions are not designed to be displayed on the web
What's the three main concepts of RDF?
Resources - "things" Properties - special resources that descries relations between resources Statements - the combination of resource, property and a property value
Describe SparQL
Semantic query-enhanced web rule language. A query language for RDF and OWL which is derieved from SQL and shares the same syntax (select - from - where)
What's the semantic web?
The term "semantic web" refers to W3C's vision of the web of linked data. Semantic web technologies enable people to create data stores on the web, build vocabularies and write rules for handling data.
What's Web Ontology Language?
Three languages where the choice depends on the extent to which users require the more expressive restriction constructs provided by OWL DL. OWL Full - maximum expressiveness without losing computational completeness. Allows an ontology to augment the meaning of the predefined (RDF or OWL) vocabulary OWL DL - supports those users who want the maximum expressiveness without losing computational completeness OWL Light - supports users who primary needs a classification hierarchy and simple constraint features
What's URI?
Uniform Resource Identifier. Identifies a resource on the internet distinctly. ex, ftp - file transfer protocol and http - hypertext transfer protocol
What's W3C's vision?
Web of data and services Web of rich interaction Web of trust Web of services
What's W3C?
World wide web consortium. An international community that developes open standards to ensure the long term growth of the web with the primary goal to make these benefits available to all people
What's the Dublin Core?
a set of predefined elements (properties) for describing documents and recording metadata
FOAF
describes characteristics of people and social groups that are independent of time and technology; as such they can be used to describe basic information about people in present day, historical, cultural heritage and digital library contexts
What's Open Graph Protocol?
enables any web page to become a rich object in a social graph. For example it's used on facebook to allow any webpage to have the same functionality as any other object on facebook
What's linked data and connectivity (RDF)
refers to a set of best practices for publishing structured data on the web