geographical service:
DESCRIPTION
Geographical Service:. A compass for the Web of Data. Gianluca Correndo , Manuel Salvadores , Yang Yang, Nicholas Gibbins , Nigel Shadbolt. Outline. Introduction Public Sector Information Ordnance Survey Qualitative Spatial Relations Geographical Service for GB SCOVO data alignment - PowerPoint PPT PresentationTRANSCRIPT
Geographical Service:
Gianluca Correndo, Manuel Salvadores, Yang Yang, Nicholas Gibbins, Nigel Shadbolt
A compass for the Web of Data
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Outline• Introduction
– Public Sector Information– Ordnance Survey– Qualitative Spatial Relations
• Geographical Service for GB– SCOVO data alignment– Geographical Service (RESTful API & frontend)– Backlinking service
• Future Work
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Public Sector Information• UK Government committed to free public sector
information– Usually Excel or CSV to RDFize (
http://data.gov.uk)– Linked Data already published (e.g. OS, Openly
Local, education, and statistics?)– More to come
• High volumes of data
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Public Sector Information• EnAKTing project investigating how to integrate it,
query it, manage it• PSI data sets usually describe the territory and its
resources– Geographical information is therefore a key
aspect of its classification– How to describe data about territory, and how to
exploit it?
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Ordnance Survey• Great Britain’s mapping agency • Released an Administrative KB of Great Britain in
Linked Data format– From European Region (e.g. South-West
England) to single parishes and constituencies– Region connection relations are also described
• There is a concrete opportunity of exploiting authoritative knowledge for providing a geographical context to the other information
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Qualitative Spatial Relations • Region Connection Calculus (RCC8) proposed by
Randell, Cui, and Cohn – Euclidean space representation and reasoning
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contains = TPPi ∪NTTPi
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contained = TPP∪NTTP
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Geographical Service for GB• All PSI data sets published so far has one
geographical dimension:– Different granularity used (from constituency to
European region)• Need to align the geographical entities to an
authoritative kb– Once aligned need to exploit such a reference – Qualitative Spatial Relations can be used then to
retrieve related entities (e.g. all sub-regions of a region)
– Need to retrieve back links from reference URIs
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Rationale for a Geographic service• Use of URIs alone for
providing context to resources is not always enough
• A semantic gap can be easily covered exploiting existing knowledge about the domain (in this case about GB geography)
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SCOVO Data Alignment• Every SCOVO data set is a collection of SCOVO
Items• Every SCOVO Item is a value plus a number of
dimensions that put the value into context• Geographical dimensions have been represented as
URIs and aligned towards the OS Administrative ontology
• Geographical service + Backlinking service retrieve the items relevant for a given region
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Geographical service – the data• OS Administrative
ontology• Co-reference service
for both inward URI normalization and outward result translation
• New knowledge (relations between entities) is created in the process
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Geographical service – the API• http://geoservice.psi.enakting.org/{command}/
{dictionary}/{format}/{URI}
– command = contains or container– dictionary = one of {dbpedia, os, geonames, statistics,
geonames, enakting, opencyc, openlylocal, none}– format = rdf or text or ttl or json– URI = input URI of the entity to make the containment
closure
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Geographical service – the API• The service takes the input URI and find via co-
reference system the equivalent URI in OS KB• The contained/container entities are retrieved via
SPARQL (forward chaining reasoning upon the OS KB)
• The resulting OS URIs are translated in the target dataset (e.g. dbpedia, enakting, etc.) via co-reference system
• The URIs are then serialized in the chosen format (i.e. text, rdf/xml, rdf/turtle, or json)
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Geographical service - frontend
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Back-linking support• Once relevant URIs have been retrieved, a further
step is usually requested• Relevant URIs are in fact usually used to provide
context to other information, it’s that information we’re aiming at– The backlinks issue is long known from
hypertext literature– Linked data world is built on top of an hypertext
framework (the Web)
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Back-linking support• The adoption of hub ontologies/KBs stresses the
problem of handling such backward references– Resolving authoritative URIs in fact does not
return all the entities that used that URIs• Application indexing services can be built for
retrieving such back links exploiting therefore authoritative sources of URIs
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