v1.0 2016-09-21 2016-06-08 The Evaluation ontology describes evaluation of [`seas:Property`ies](https://w3id.org/seas/Property). There may be: - direct evaluations, or - qualified evaluations. Figure below provides an overview of the concepts in this ontology: [](https://w3id.org/seas/evaluation.png) ### Direct evaluations The `seas:Property` may be given a unique, constant, quality or quantity value. This is done using properties: - [`seas:value`](https://w3id.org/seas/value), if the value is modeled as a RDF IRI or blank node; - [`seas:simpleValue`](https://w3id.org/seas/simpleValue), if the value is modeled as a RDF Literal. A quality value may be any resource. A quantity value may use external vocabularies such as QUDT (it would then be a [qudt:Quantity](https://qudt.org/schema/qudt#QuantityValue)), or OM (it would then be a [om:Quantity](http://www.wurvoc.org/vocabularies/om-1.8/)), or be directly encoded as a literal using an appropriate datatype. #### Using QUDT The SEAS ontologies are compatible with the QUDT ontologies. The alignment between SEAS and QUDT is expressed in [an external module](https://w3id.org/seas/QUDTAlignment) that imports the Evaluation ontology: - `qudt:Quantity` is a subclass of `seas:Property`; - `qudt:quantityValue` is a subproperty of `seas:evaluation`; - `qudt:QuantityValue` is a subclass of `seas:Evaluation`; - `qudt:numericValue` is a subproperty of `seas:evaluatedValue`. #### Using OM The SEAS ontologies are compatible with the OM ontologies. The alignment between SEAS and OM has not yet been expressed in an external module. Please [get in contact with us](https://w3id.org/seas/team-list.html) if this is of interest to your project. #### Expressing values using custom datatypes We are working on a custom datatype identified by `cdt:ucum`. The lexical value of a cdt:ucum is defined as follows : ``` unum ::= number ’ ’ unit number ::= noDecimalPtNumeral | decimalPtNumeral | scientificNotationNumeral unit ::= (see the Unified Code of Units of Measure specification) ``` `noDecimalPtNumeral`, `decimalPtNumeral` and `scientificNotationNumeral` are defined in the XSD 1.1 recommendation. This datatype should either be hardcoded in RDF engines, or could be specified as a [Linked Datatype](https://w3id.org/lindt/), making it easy for any SPARQL engine to support the comparison of quantity values. For example, the following triples quantify the consumption of a fridge using `cdt:ucum` literals: ``` <fridge/1/consumption/frequency> seas:simpleValue "50.1 Hz"^^cdt:ucum . <fridge/1/consumption/voltage> seas:simpleValue "231 V"^^cdt:ucum . <fridge/1/consumption/tension> seas:simpleValue "2432 mA"^^cdt:ucum . <fridge/1/consumption/voltageTensionPhase> seas:simpleValue "1.68 RAD"^^cdt:ucum . ``` ### Qualified evaluations Because property values may evolve in space and time, or because they can be approximate measures or forecasts, class [`seas:Evaluation`](https://w3id.org/seas/Evaluation) qualifies the link [`seas:value`](https://w3id.org/seas/value). In particular, an instance of seas:Evaluation may hold metadata about: 1. the type of evaluation; 2. the context of validity of the evaluation; 3. provenance information or any other data. Let us shortly describe each of these categories. #### The type of evaluation The type of evaluation is defined by the hierarchy of `seas:Evaluation` sub classes. This hierarchy includes classes such as: - [seas:TimeAverageEvaluation](https://w3id.org/seas/TimeAverageEvaluation): the given value is the average of the property value over its temporal context; - [seas:MaximumOperatingEvaluation](https://w3id.org/seas/MaximumOperatingEvaluation): the given value is the maximum operating value for the property in all of its validity context. #### The evaluation validity context An evaluation validity context is described using functional sub properties of [seas:hasValidityContext](https://w3id.org/seas/hasValidityContext). The SEAS ontologies define two such properties: - [seas:hasTemporalContext](https://w3id.org/seas/hasTemporalContext) links an entity to its temporal validity context, a [time:TemporalEntity](http://www.w3.org/2006/time#TemporalEntity); - [seas:hasSpatialContext](https://w3id.org/seas/hasSpatialContext) links an entity to its spatial validity context, a [geo:SpatialThing](http://www.w3.org/2003/01/geo/wgs84_pos#SpatialThing). #### Provenance or other metadata Other metadata may be added to describe an evaluation instance. For example the W3C [PROV Ontology](https://www.w3.org/TR/prov-o/) enables to describe the activity that generated the evaluation, or its generation time. Other vocabularies may be used to further describe evaluations. See the [Linked Open Vocabulary cloud](http://lov.okfn.org/dataset/lov/). #### Examples The day-ahead forecasted temperature at Aeroport de Lyon is 28.3 °C: ``` <air/temperature> seas:evaluation [ a seas:TemperatureEvaluation , seas:exactEvaluation , seas:Forecast ; prov:wasGeneratedBy <algorithm/1/execution/234> ; prov:generatedAtTime "2016-08-12T12:00:00Z"^^xsd:dateTime ; seas:hasTemporalContext [ a time:Instant ; time:inXSDDateTime "2016-08-13T12:00:00Z"^^xsd:dateTime ] ; seas:hasSpatialContext [ a geo:Point ; geo:lat 45.7242502 ; geo:long 5.0914517 ] ; seas:evaluatedSimpleValue "28.3 °C"^^cdt:ucum ] . ``` The average frequency of property `<fridge/1/consumption/frequency>` over time interval 12:00 - 13:00, as generated by `<algorithm/1/execution/12>`, is 50.1054 Hz: ``` <fridge/1/consumption/frequency> seas:evaluation [ a seas:FrequencyEvaluation , seas:TimeAverageEvaluation ; prov:wasGeneratedBy <algorithm/2/execution/12> ; seas:hasTemporalContext [ a time:Interval ; time:hasBeginning [ time:inXSDDateTime "2016-09-10T12:00:00Z"^^xsd:dateTime ] ; time:hasEnd [ time:inXSDDateTime "2016-09-10T13:00:00Z"^^xsd:dateTime ] ] ; seas:evaluatedSimpleValue "50.1054 Hz"^^cdt:ucum ] . ``` The minimal operating value of `<fridge/1/consumption/frequency>` is 47.0 Hz: ``` <fridge/1/consumption/frequency> seas:evaluation [ a seas:MinimalOperatingValueEvaluation ; seas:evaluatedSimpleValue "47.0 Hz"^^cdt:ucum ; ] . ``` seas The SEAS Evaluation ontology stable Evaluations qualify the link [`seas:value`](https://w3id.org/seas/value). In particular, they may hold metadata about: 1. the type of evaluation; 2. the context of validity of the evaluation; 3. provenance information or any other data. Evaluation testing Average Evaluation is an Evaluation wich evaluate the sum of a list of evaluations divided by the number of evalautions in the list. Average Evaluation testing Minimum Evaluation is an Evaluation which is the minimum value that the evaluation can take for the evaluated property. Minimum Evaluation testing Maximum Evaluation is an Evaluation which is the maximum value that the evaluation can take for the evaluated property. Maximum Evaluation stable Links an evaluation to the literal that qualifies some aspect of the property, modeled as a RDF IRI or blank node. evaluated value stable Links some object to one of its validity contexts. A validity context is described using functional sub properties of [seas:hasValidityContext](https://w3id.org/seas/hasValidityContext). There are two such properties defined: - [seas:hasTemporalContext](https://w3id.org/seas/hasTemporalContext) links an entity to its temporal validity context, a [time:TemporalEntity](http://www.w3.org/2006/time#TemporalEntity); - [seas:hasSpatialContext](https://w3id.org/seas/hasSpatialContext) links an entity to its spatial validity context, a [geo:SpatialThing](http://www.w3.org/2003/01/geo/wgs84_pos#SpatialThing). has validity context stable Links a property to a unique, constant, quality or quantity value for that property, modeled as a RDF IRI or blank node. For example, the exact length of `<car/1>` is 4.27 m, and this is true in the validity context of the RDF graph. ``` <car/1/length> a seas:Property ; seas:value [ a qudt:QuantityValue ; qudt:numericalValue 4.27 ; qudt:unit qudt-unit:meter ] . ``` This property is a shortcut for an exact evaluation with all context being the most generic contexts (although this notion is not planned to be formalized). value stable Links a property to a unique, constant, quality or quantity value for that property, modeled as a RDF Literal. For example, the exact length of `<car/1>` is 4.27 m, and this is true in the validity context of the RDF graph. ``` <car/1/length> a seas:Property ; seas:simpleValue "4.27 m"^^cdt:ucum . ``` This property is a shortcut for an exact evaluation with all context being the most generic contexts (although this notion is not planned to be formalized). simple value stable Links an evaluation to the literal that qualifies some aspect of the property, modeled as a RDF Literal. evaluated simple value stable Links an evaluation to the one and only property it evaluates. evaluation of stable Links an evaluation to its spatial validity context, a [geo:SpatialThing](http://www.w3.org/2003/01/geo/wgs84_pos#SpatialThing). has spatial context stable Links an evaluation to its temporal validity context, a [time:TemporalEntity](http://www.w3.org/2006/time#TemporalEntity). has temporal context stable Links a property to one of its evaluations. evaluation