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The requirement – time-constrained relationships. ‘ Editor ’ is a role in the relationship between a person and a document ‘ Under review ’ is a possible status of a document in the publishing workflow
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The requirement – time-constrained relationships • ‘Editor’ is a role in the relationship between a person and a document • ‘Under review’ is a possible status of a document in the publishing workflow • Such roles and statuses may hold only during a defined period of time, and may also be contingent on events controlled by agents – such as the editor sending the document to a reviewer • We need a generic straightforward way to encode such time-constrained roles and statuses in RDF
The problem – such encoding is not trivial in RDF • Because of the sheer simplicity of the subject-predicate-object triple, OWL ontologies and RDF-based models are not able to handle qualifications such as time periods and contexts directly • Instead we need a workaround such as reification or, more generally, an n-ary description • Ontological patterns have been developed to address this issue • For example, by using the time-indexed situation pattern (http://ontologydesignpatterns.org/cp/owl/timeindexedsituation.owl), it becomes possible to link a subject to a time-dependent situation
Encoding Publishing Roles • We have previously used this time-indexed situation pattern to create • PRO, the Publishing Roles Ontology (http://purl.org/spar/pro/) • PRO permit roles of people (e.g. editor, reviewer) to be encoded for specific periods of time, and in relationship to particular organizations or documents
Encoding Publishing Roles • If we look just at the core of this ontology, we see that this ontology pattern has two important advantages: • First, it relates the subject directly to its role in time • Second, it permits new roles to be specified simply by adding new individuals as members of the class pro:Role, without having to modify the ontology • This is much simpler that having to add a new ‘relationship’ class for each new role :shottona foaf:Person ; pro:holdsRoleInTime [ a pro:RoleInTime ; pro:withRolepro:author ; pro:relatesToDocument :adventures-in-semantic-publishing ] .
Diagrammatic representation of PSO • We have similarly used this time-indexed situation pattern to create • PSO, the Publishing Status Ontology (http://purl.org/spar/pso/) .
Encoding Publishing Statuses • Here, a document status, such as being under review, can be associated with an event related to an agent, for example the event of sending the paper to a reviewer by an editor, and with a particular timespan of the reviewing process :adventures-in-semantic-publishing a foaf:Document ; pso:holdsStatusInTime [ a pso:StatusInTime ; pso:withStatus pso:under-review ; pso:isAcquiredAsAConsequenceOf [ a part:Event ; rdfs:label “The sending of the paper to a reviewer” ; part:hasParticipant [ a pso:Agent ; pro:holdsRoleInTime [ a pro:RoleInTime ; pro:withRole pro:editor ; pro:relatesToDocument :adventures-in-semantic-publishing ] ] ; tisit:atTime [ a ti:TimeInterval ; ti:hasIntervalStartDate “2008-01-13T00:00:00”xsd:dateTime ; ti:hasIntervalEndDate “2009-03-09T00:00:00”xsd:dateTime ] ] .
CERRO, the CERIF Roles and Relationships Ontology • CERIF is the Common European Research Information Framework • As a contribution to CERIF, we have now used exactly this same ontology design pattern to create CERRO, the CERIF Roles and Relationships Ontology • CERRO is available at http://purl.org/cerif/cerro • CERRO complements and extends the draft CERIF and SEMCERIF ontologies developed by the Linked Data Task Group of euroCRIS • We have proposed the adoption of CERRO in a document available at http://imageweb.zoo.ox.ac.uk/pub/2012/cerif/Shotton-Peroni_Proposal-for-CERRO-the-CERIF-Relationships-Ontology.docx
CERRO Roles, and using roles as object properties • CERRO contains 69 relationships, for example • cerro:author - with respect to a paper, a publisher, etc. • cerro:data-manager - with respect to a project, a dataset, etc. • cerro:principal investigator - with respect to a project, an institution, etc. • CERRO used the OWL 2 DL capabilities for meta-modelling (known as OWL punning) • This permits the individuals of a class cerro:Relationship also to be represented as object properties in the CERRO ontology • This has the advantage that • if one does not need to employ cerro:RelationshipInTime in order to specify temporal constraints on a relationship • the relationship can be used directly as an object property to relate the subject to the object
Examples of CERRO usage :shotton a cerif:Person ; cerro:holdsRelationshipInTime [ a cerro:RelationshipInTime ; cerro:withRelationship cerro:principal-investigator ; cerro:linksToObjectEntity [ a cerif:Project ; dcterms:title “The Open Citation Project” ; foaf:homePage <http://opencitations.net> ] ; tisit:atTime [ a ti:TimeInterval ; ti:hasIntervalStartDate “2010-06-16T00:00:00”xsd:dateTime ; ti:hasIntervalEndDate “2011-06-16T00:00:00”xsd:dateTime ] ] . • Clear, direct and unambiguous :shottona cerif:Person ; cerro:principal-investigator[ a cerif:Project ; foaf:homePage <http://opencitations.net> ] .
Advantages of using CERRO • The time-indexed relationship is associated directly with a cerif:CoreEntity • The time-indexed relationship is held directly with respect to another cerif:Entity • The starting and ending times refer directly to the cerro:RelationshipInTime • There is no need to specify a new additional indirect ‘linking’ URI for each pair of entities to be linked, with which URI the times are associated • There is no need to specify many different link properties, one for each type of relationship, e.g. cerif:isLinkedByPerson, cerif:isLinkedToProject • A new relationship can easily be specified by adding a new individual to the class cerro:Relationship, without having to change the structure of the ontology • CERRO is complete, published on SourceForge, open source and ready to use • All classes and properties are fully defined and appropriately restricted • The ontology is written in validated OWL 2 DL • CERRO is designed to be used with the draft CERIF and SEMCERIF ontologies