Ratings Ontology 

Ratings ontology is an OWL based format that provides classes and properties to represent in an exhaustive and machine processable way ratings collected by web sites, automated agents and other engines.

Name Space : http://www.tvblob.com/ratings/#

Ratings Ontology specification in OWL 

Overview 

Ratings

A rating represents a sort of preference, or judgement, assessed by a user or a software agent about a generic item. A rating can have a value. It is an additional information, whose interpretation depends on the context in which the rating has been produced. To assure processability and uniformity for third parties software, a rating value must be numerical, in the sense that it must be a typed literal with a numeric data type. In a context where no values are assigned to ratings, a rating should be considered as a positive assertion, but the the absence of a rating should be considered like an unknown value, and not as a negative assertion.

Rating Collectors

Represents a rating entry point. RatingsCollector instances contains also a description of the set of available ratings, usually a web site. Contains information about the rating  context and the engine responsible for the collection. For each rating collector the mode in which this engine works has to be specified. In the EXPLICIT mode the asserter is explicitly asked to enter a rating about a resource, i.e. by using a form. The IMPLICIT mode covers all scenarios in which the user is not asked explicitly to assess a rating, but ratings are produced observing her behaviour. Ratings ontology provides two different ways to define the range of available ratings. The first one models a discrete finite ratings set via exhaustive enumeration of available rating values. For this purpose Ratings Ontology offers the property hasAllowedRatingValue, that allows to specify one by one allowed rating values.

The second mechanism is more general but less expressive. At first an interval can be bounded or unbounded, in one or both directions. The hasRatingsRangeLowerBound and hasRatingsRangeUpperBound properties respectively allow to define an upper and a lower bound for a ratings range.

A range defined in this manner is assumed to be continuous. If we have a finite or not finite ratings range, in which available values are equally spaced we an encode it with the equispacedRatingsDistance property. Obviously, such a range consists of a set of discrete values.

Definitions 

Datatypes

Ratings Ontology defines a new data type numerical as the union of double, decimal and integer.

Properties 

Classes

Individuals

Examples

The following fragments contains some usage examples of Ratings Ontology classes. We use the abbreviation rat to denote the ratings ontology name-space, and xsd for the xml schema data types one.

Example 1. A Simple Rating Without Value

<rat:Rating>

	<rat:assessedBy>

		<foaf:Person>

			</foaf:name>MyName</foaf:name> 

		</foaf:Person> 

	<rat:assessedBy>
 	<rat:about rdf:resource="http://www.example.org/anItem" />

	<rat:collectedBy rdf:resource="http://acollector.example.org" /> 

</rat:Rating> 

Example 2. A valued rating

<rat:Rating>

	<rat:assessedBy rdf:resource="http://www.example.org/anuser" />

 	<rat:about rdf:resource="http://www.example.org/anItem" />

	<rat:value rdf:datatype="&xsd;integer">

		4

	</rat:value> 

	<rat:collectedBy rdf:resource="http://acollector.example.org" /> 

</rat:Rating> 

Example 3. A Ratings Collector with a discrete finite set of available rating values

This ratings collector collect ratings with values in {1,2,3} in explicit mode.

<rat:RatingsCollector>

    <rat:mode rdf:resource="&rat;EXPLICIT_MODE" />

    <rat:hasAllowedRatingValue rdf:datatype="&xsd;integer">

        1

    </rat:hasAllowedRatingValue>

    <rat:hasAllowedRatingValue rdf:datatype="&xsd;integer">

        2

    </rat:hasAllowedRatingValue>

    <rat:hasAllowedRatingValue rdf:datatype="&xsd;integer">

        3

    </rat:hasAllowedRatingValue>

</rat:RatingsCollector>

Exampe 3. A Ratings Collector with a bound interval as allowed rating values range

This example describe a ratings collector that allows rating values in the continuous interval [0;1].

<rat:RatingsCollector>

	<rat:mode rdf:resource="&rat;IMPLICIT_MODE" />

	<rat:hasRatingValuesRangeLowerBound rdf:datatype="&xsd;integer">

		0

	</rat:hasRatingValuesRangeLowerBound>

	<rat:hasRatingValuesRangeUpperBound rdf:datatype="&xsd;integer">

		1

	</rat:hasRatingValuesRangeUpperBound>

</rat:RatingsCollector>

Exampe 4. A Ratings Collector with an unbound interval as allowed rating values range

A rating collector with ratings in [0.5; +inf [ 

<rat:RatingsCollector>

	<rat:mode rdf:resource="&rat;IMPLICIT_MODE" />

	<rat:hasRatingValuesRangeLowerBound rdf:datatype="&xsd;integer">

		0.5

	</rat:hasRatingValuesRangeLowerBound>

</rat:RatingsCollector>

Example 5. Another Ratings Collector with an unbound rating values range

In this example the set of available rating values is the even numbers one. 

<rat:RatingsCollector>	

    <rat:mode rdf:resource="&rat;EXPLICIT_MODE" />	

    <rat:hasRatingValuesRangeLowerBound rdf:datatype="&xsd;integer"> 		

        0  	

    <rat:hasRatingValuesRangeLowerBound>

    <rat:ratingsEquispacedWithDistance rdf:datatype="&xsd;integer">

        2

    </rat:ratingsEquispacedWithDistance> 

</rat:RatingsCollector>

External References

1. Review Ontology
2. Web Ontology Language(OWL)