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Semantic Web Challenges for Visualisation & VA

Alan DixLancaster University

and Talis

hcibook.com/alanalandix.com/blog

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Semantic Web – What is it?

• web of data for computation

• technologies: RDF, OWL, triples and ontologies– everything comes in threes

<http://alandix.com/me> <foaf:name> “Alan Dix” .<http://alandix.com/me> <bz:works_at>

<http://talis.com/> .

• linking (open) data

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LOD cloud

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three paths to Sem Web

SemWeb:RDF,etc.

<fresh><semantic>

<data>

from HTMLadd markup (RDFa)

or data detectors

from existing data(CSV, RDMS, etc.)

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from raw data to semantic data

<RDF><triples>

existingraw data

linkedopen data

convert /describe

linkage(via URIs)

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existing raw data

• understanding:data, domain, connections

• focus on structure• heterogeneous representations• different views (for different purposes)

de-normalised• sub-unit semantics (e.g. “1000 kp rising” )

• super-unit semantics (e.g. lat&long)

<RDF>

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converting / describing

• identity:are two things in different places the same

• rules and exceptionslarge so try to do it with rules (e.g. natural

keys)but need exceptions when rules don’t hold

... finding them – outliers

• combination of hand-craft and crafted automation= visual analytics !!

<RDF>

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RDF / Semantic Data

• schema-lessvocabulary, but optional schema

• potentially rich class & predicate typescoloured graph, not just tables!sometimes level mixing (meta-instance)and maybe BIG

• sometimes text + structure (e.g. ODP)but many small text units (unlike classic IR)

<RDF>

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linkage

• establishing identity• value relationships

• similar issues to raw=>RDF transformation

<RDF>

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linked open data

• heterogeneous• incomplete• pluggable visualisations• URI links ... but also value relationships• very BIG – the web of data

<RDF>

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let me know what you do!