Part II

Property domain and range restriction RDFS allows us to put restriction on the properties by specifying their domain and range, providing the semantic links between classes and properties The rdfs : domain and rdfs : range properties allow us to define the subject and object (both object type and datatype) of a property in a rdf triple, respectively hydro:contaminate rdfs:domain petr:Lead. hydro:contaminate rdfs:range hydro:Groundwater. Do you think the following leads to an error or it is a flaw? bio : cathydro : contaminate sport : basketball Answer: The reasoner assumes basketball is groundwater and that cat is lead; no error, but it is a wrong type matching! We need to put restriction on the domain and range types!

Code in N3 and RDF/XML format contaminate rdfs:domain Lead. contaminate rdfs:range Groundwater.

Property Intersection in RDFS Again, as is the case for classes, rdfs cannot directly model logical intersection and union for properties, although we can use the rdfs:subPropertyOf If we define property P to be the intersection of R and S (i.e., P  R  S), and two resources x and y are related by property P: Semantics: IF x P y THEN x R y x S y xy P AB RS

Example  After precipitation, water infiltrates into the ground and/or runs off on the surface of the ground :infiltrate rdfs:subPropertyOf :recharge  If water infiltrates the Floridan Aquifer (an instance); it recharges it: hydro: Water hydro: infiltratehydro: FloridanAquifer. hydro: Water hydro: rechargehydro: FloridanAquifer.  This is a one way inference, i.e., when water infiltrates an aquifer, it recharges it, but if an aquifer is recharged, it may not be because of infiltration xy infiltrate WaterAquifer recharge

infiltrate subPropertyOf recharge

infiltrate and recharge properties

… </rdf:Description

Combination of set union and rdfs:subClassOf Recall that the union of set A and B (A  B) contains elements that are contained only in A, only in B, or in both A and B Let the union of sets A and B be a member of set C (i.e., A  B  C), which means that each of the A and B sets is a subclass of C (i.e., C is the superclass of both A and B) C BA A  B  C x

Union A rdfs : subClassOf C. B rdfs : subClassOf C. In this case, any member (object x) of A or of B is also a member of set C: x rdf : type A. or x rdf : type B.  implies x rdf : type C. A  B  C x C BA x

Example  K-Ar age and Rb-Sr age are types of isotopic age x rdf : type A. or x rdf : type B. implies x rdf : type C. : KArAgerdfs : subClassOf: IsotopicAge. : RbSrAge: rdfs : subClassOf: IsotopicAge. IsotopicAge RbSrAgeKArAge

Example  If we know: : Age-1 rdf : type: KArAge. : Age-2rdf : type: RbSrAge. : KArAgerdfs : subClassOf: IsotopicAge. : RbSrAge: rdfs : subClassOf: IsotopicAge.  Then, we can infer that both ages are isotopic ages. : Age-1rdf : type: IsotopicAge. : Age-2rdf : type: IsotopicAge.  This inference is uni-directional, i.e., every K-Ar or Rb-Sr age is an isotopic age, but an isotopic age may not be K-Ar or Rb-Sr (it could be U-Th, for example) IsotopicAge RbSrAgeKArAge Age-1Age-2

Short format RDF/XML code

Property Union  This is useful when we combine properties from two different sources which may mean the same thing!  If two source classes use property P and T with same meaning (different names), then a combined property S can be defined using the rdfs:subPropertyOf P rdfs : subPropertyOf S. T rdfs : subPropertyOf S.  If there are two resources x and y, which are related either by P (shown) or T, then we can infer that they are related by S x P y. or x T y. Then x S y. xy S P or T AB

Making two Properties Equivalent  Two groups of geologists (e.g., Geochemistry and Tectonics groups) have knowledge bases, in which one group uses the property studies and the other one uses investigates for a job done by its geologists  Assuming that the ‘investigates’ and ‘studies’ properties mean the same thing, we make them equivalent the following way: geochem : studiesrdfs : subPropertyOf tect : investigates. tect : investigatesrdfs : subPropertyOf geochem : studies.  This way, the two properties of the Geochemistry and Tectonics group become equivalent  Note: we can also use owl:equivalentProperty

Union Alternative  The second way of doing this is by defining a super-property (the union pattern), such as ‘works’, for both properties  This way, different properties of the two groups (which actually mean the same thing) are combined under the same ‘works’ property, making it easy to merge the information from the two sources geochem : studies rdfs : subPropertyOf : works. tect : investigates rdfs : subPropertyOf : works. works studiesinvestigates

Same for ‘investigates’

RDF/XML code

Properties From Different Sources  Importing and equating properties from different sources can be done with the use of the rdfs:subPropertyOf  For example, if hydrogeology knowledge base calls ‘flow’ for what structural geology knowledge base calls ‘transport, we can use the rdfs:subPropertyOf as long as the domain and range of these various properties are the same  That is, we want to say that all uses of ‘transport’ and ‘move’ properties are the same: hydro : transport rdfs : subPropertyOf struc : move

Example If we have a triple: ‘ x hydro:transport y ’ in hydrogeology we can infer ‘ x struc:move y ’ in structural geology as long as x and y are of related types (e.g., water transport ion, fluid move ion) hydro : Water hydro : transportgeochem : Ion. struc : Fluid struc : movegeochem : Ion. struc : move hydro : transport x A y A

RDFS Containers The qualified name rdfs:Container is the general superclass of the rdf:Bag, rdf:Seq, and rdf:Alt, allowing us to mark a resource as a list without defining the specific type The rdfs:ContainerMembershipProperty is a subclass of the rdfs:Property class, and is used to specify containedness of one resource in another River has dissolved load, suspended load, and bed load: hydro:hasLoad rdf:type rdfs:ContainerMembershipProperty hydro:hasDissolvedLoad rdfs: subPropertyOf hydro:hasLoad RiverWaterhasDissolvedLoadIon If cement is contained in a clastic rock, then hasCement rdf:type rdfs:ContainerMembershipProperty

rdfs:member An instance of the rdfs:ContainerMembershipProperty is a subproperty of the rdfs:member property ConglomeratehasCementCement Conglomeraterdfs:memberCement RiverWaterhasDissolvedLoadIon RiverWaterrdfs:memberIon Note: We can also model these with the hasPart and partOf properties

rdfs : label property  The rdfs:label offers a printable label for the name of a resource (class, property, individual) for human consumption. The object of rdfs:label has to be a literal rdfs : label rdfs : range xsd : string Or in RDF/XML Gem  To achieve this, we need to define the properties, with string values, as a rdfs:subPropertyOf the rdfs:label  The labels can then be returned if queried. : MapNamerdfs:subPropertyOfrdfs:label. : InvestigatorNamerdfs:subPropertyOfrdfs:label.

Other rdfs properties The rdfs:seeAlso and rdfs:isDefinedBy provide extra information and link to the primary source of information, respectively, for a resource The object of the rdfs:isDefinedBy property defines the subject (i.e., provides more info about the subject) The rdfs:isDefinedBy is a subproperty of the rdfs:seeAlso

More qnames (URI) rdfs:seeAlso rdf:resource=“ The rdfs:comment property offers a natural language comment for any triple, for example: geochem : precisionrdfs : Comment “Precision relates to the instrument.” Or in RDF/XML: Gems are minerals