1. Geographical Service: Gianluca Correndo, Manuel Salvadores, Yang Yang, Nicholas Gibbins, Nigel Shadbolt A compass for the Web of Data

2. 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 2

3. Public Sector Information UK Government committed to free public sector information –Usually Excel or CSV to RDFize (http://data.gov.uk)http://data.gov.uk –Linked Data already published (e.g. OS, Openly Local, education, and statistics?) –More to come High volumes of data 3

4. 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? 4

5. 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 5

6. Qualitative Spatial Relations Region Connection Calculus (RCC8) proposed by Randell, Cui, and Cohn –Euclidean space representation and reasoning 6

7. 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 7

8. 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) 8

9. 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 9

10. 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 10

11. 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 11

12. 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) 12

13. Geographical service - frontend 13

14. 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) 14

15. 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 15

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