Databases Reference
In-Depth Information
to the e
cient execution of link specifications. In addition, developing reduction-ratio
optimal algorithms for spaces other than Minkowski spaces promises to ensure the best
possible use of available hardware. Finally, devising more e
cient means to combine
single algorithms is the third open area of research in this domain. The challenges faces
with regard to learning link specifications are also manifold and include devising ap-
proaches that can e
ciently detected most informative positive and negative examples
as well even running in a fully unsupervised manner on properties that are not one-to-
one relations.
Linked Data Visualization.
The potential of the vast amount of Linked Data on the
Web is enormous but in most cases it is very di
cult
and
cumbersome for users to
visualize, explore and use this data, especially for lay-users [37] without experience
with Semantic Web technologies. Visualizations are useful for obtaining an overview
of the datasets, their main types, properties and the relationships between them. Com-
pared to prior information visualization strategies, we have a unique opportunity on the
Data Web. The unified RDF data model being prevalent on the Data Web enables us
to bind data to visualizations in an
unforeseen
and
dynamic
way. An information visu-
alization technique requires certain data structures to be present. When we can derive
and generate these data structures automatically from reused vocabularies or semantic
representations, we are able to realize a largely automatic visualization workflow. Ulti-
mately, various visualizations techniques can develop an ecosystem of data extractions
and visualizations, which can be bound together in a dynamic and unforeseen way. This
will enable users to explore datasets even if the publisher of the data does not provide
any exploration or visualization means. Yet, most existing work related to visualizing
RDF is focused on concrete domains and concrete datatypes.
Acknowledgments.
We would like to thank our colleagues from the AKSW research
group in Leipzig as well as the LOD2 and GeoKnow project consortia, without whom
writing this chapter would not have been possible. In particular, we would like to thank
Christian Bizer and Tom Heath, whose Chaper 2 of the topic 'Linked Data - Evolving
the Web into a Global Data Space' [54] served as a blueprint for Section 2; Sebastian
Hellmann, Claus Stadler, Jörg Unbehauen for their contributions to Section 3, Sebastian
Tramp, Michael Martin, Norman Heino, Phillip Frischmuth and Thomas Riechert for
their contributions to the development of OntoWiki as described in Section 4. This
work was supported by a grant from the European Union's 7th Framework Programme
provided for the projects LOD2 (GA no. 257943), GeoKnow (GA no. 318159) and the
Eureka project SCMS.
References
1. Resource description framework (RDF): Concepts and abstract syntax. Technical report,
W3C 2 (2004)
2. Adida, B., Birbeck, M., McCarron, S., Pemberton, S.: RDFa in XHTML: Syntax and pro-
cessing - a collection of attributes and processing rules for extending XHTML to support
RDF. W3C Recommendation (October 2008),
http://www.w3.org/TR/rdfa-syntax/
