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title TARGET DECK FILE TAGS tags
RDF Schema Obsidian::STEM data_model::rdf::schema
rdf

Overview

The simplest extension to RDF that allows a modeler to manage inference is RDF Schema (RDFS). Triples that are inserted directly into an underlying RDF store are called asserted triples. Triples that are derived from inference rules are called inferred triples.

%%ANKI Basic What is considered the simplest extension to RDF that enables inference? Back: RDFS. Reference: Allemang, Dean, James A. Hendler, and Fabien L. Gandon. Semantic Web for the Working Ontologist. 3e ed. ACM Books 33. New York: Association for computing machinery, 2020.

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%%ANKI Basic What is RDFS an acronym for? Back: Resource Description Framework Schema. Reference: Allemang, Dean, James A. Hendler, and Fabien L. Gandon. Semantic Web for the Working Ontologist. 3e ed. ACM Books 33. New York: Association for computing machinery, 2020.

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%%ANKI Cloze An {asserted} triple is contrary to an {inferred} triple. Reference: Allemang, Dean, James A. Hendler, and Fabien L. Gandon. Semantic Web for the Working Ontologist. 3e ed. ACM Books 33. New York: Association for computing machinery, 2020.

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%%ANKI Basic What does it mean for a triple to be asserted? Back: The triple exists directly in the underlying RDF store. Reference: Allemang, Dean, James A. Hendler, and Fabien L. Gandon. Semantic Web for the Working Ontologist. 3e ed. ACM Books 33. New York: Association for computing machinery, 2020.

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%%ANKI Basic What does it mean for a triple to be inferred? Back: The triple is derived from some set of inference rules. Reference: Allemang, Dean, James A. Hendler, and Fabien L. Gandon. Semantic Web for the Working Ontologist. 3e ed. ACM Books 33. New York: Association for computing machinery, 2020.

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%%ANKI Cloze {Asserted} triples are used to derive {inferred} triples. Reference: Allemang, Dean, James A. Hendler, and Fabien L. Gandon. Semantic Web for the Working Ontologist. 3e ed. ACM Books 33. New York: Association for computing machinery, 2020.

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%%ANKI Basic When might a triple be both asserted and inferred? Back: When the inference engine infers an already existing triple. Reference: Allemang, Dean, James A. Hendler, and Fabien L. Gandon. Semantic Web for the Working Ontologist. 3e ed. ACM Books 33. New York: Association for computing machinery, 2020.

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Classes

All things described by RDF are called resources. Resources may be divided into groups called classes. Classes are themselves resources. The rdf:type property may be used to state that a resource is an instance of a class. Associated with a class is a set, called the class extension of the class, which is the set of the instances of the class. A class may be a member of its own class extension.

The group of resources that are RDFS classes is itself a class called rdfs:Class. The rdfs:Resource class is the class of everything.

If a class C is a subclass of a class C', then all instances of C will also be instances of C'. The rdfs:subClassOf property may be used to state that one class is a subclass of another.

%%ANKI Basic What is a resource? Back: Anything described by RDF. Reference: “RDF 1.2 Schema,” accessed January 11, 2025, https://www.w3.org/TR/rdf12-schema/#ch_class.

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%%ANKI Cloze {Resources} may be divided into groups called {classes}. Reference: “RDF 1.2 Schema,” accessed January 11, 2025, https://www.w3.org/TR/rdf12-schema/#ch_class.

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%%ANKI Basic Is every resource a class? Back: No. Reference: “RDF 1.2 Schema,” accessed January 11, 2025, https://www.w3.org/TR/rdf12-schema/#ch_class.

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%%ANKI Basic Is every class a resource? Back: Yes. Reference: “RDF 1.2 Schema,” accessed January 11, 2025, https://www.w3.org/TR/rdf12-schema/#ch_class.

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%%ANKI Cloze The {rdf:type} property states {a resource is an instance of a class}. Reference: “RDF 1.2 Schema,” accessed January 11, 2025, https://www.w3.org/TR/rdf12-schema/#ch_class.

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%%ANKI Cloze The {rdfs:subClassOf} property states {a class is a subclass of another}. Reference: “RDF 1.2 Schema,” accessed January 11, 2025, https://www.w3.org/TR/rdf12-schema/#ch_class.

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%%ANKI Basic Which property describes "?A is an instance of ?B"? Back: rdf:type Reference: “RDF 1.2 Schema,” accessed January 11, 2025, https://www.w3.org/TR/rdf12-schema/#ch_class.

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%%ANKI Basic Which property describes "?A's class extension is a subset of ?B's"? Back: rdfs:subClassOf Reference: “RDF 1.2 Schema,” accessed January 11, 2025, https://www.w3.org/TR/rdf12-schema/#ch_class.

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%%ANKI Basic What is the class extension of a class? Back: The collection of instances of the class. Reference: “RDF 1.2 Schema,” accessed January 11, 2025, https://www.w3.org/TR/rdf12-schema/#ch_class.

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%%ANKI Basic Which class is the class of everything? Back: rdfs:Resource Reference: “RDF 1.2 Schema,” accessed January 11, 2025, https://www.w3.org/TR/rdf12-schema/#ch_class.

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%%ANKI Basic What does the rdfs:Resource class describe? Back: Any RDF resource. Reference: “RDF 1.2 Schema,” accessed January 11, 2025, https://www.w3.org/TR/rdf12-schema/#ch_class.

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%%ANKI Basic What is the class extension of rdfs:Resource? Back: Every resource. Reference: “RDF 1.2 Schema,” accessed January 11, 2025, https://www.w3.org/TR/rdf12-schema/#ch_class.

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%%ANKI Cloze The meaning of the {rdfs:subClassOf} property is given by the {type propagation} rule. Reference: “RDF 1.2 Schema,” accessed January 11, 2025, https://www.w3.org/TR/rdf12-schema/#ch_class.

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%%ANKI Basic Which two properties make up the type propagation rule? Back: rdf:type and rdfs:subClassOf. Reference: “RDF 1.2 Schema,” accessed January 11, 2025, https://www.w3.org/TR/rdf12-schema/#ch_class.

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%%ANKI Cloze The type propagation rule states:

  • if {?A rdfs:subClassOf ?B}
  • and {?x rdf:type ?A}
  • then {?x rdf:type ?B}. Reference: Allemang, Dean, James A. Hendler, and Fabien L. Gandon. Semantic Web for the Working Ontologist. 3e ed. ACM Books 33. New York: Association for computing machinery, 2020.

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%%ANKI Basic How is the type propagation rule stated in SPARQL? Back:

CONSTRUCT { ?x rdf:type ?B }
    WHERE { ?A rdf:subClassOf ?B. ?x rdf:type ?A }

Reference: Allemang, Dean, James A. Hendler, and Fabien L. Gandon. Semantic Web for the Working Ontologist. 3e ed. ACM Books 33. New York: Association for computing machinery, 2020.

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Bibliography

  • Allemang, Dean, James A. Hendler, and Fabien L. Gandon. Semantic Web for the Working Ontologist. 3e ed. ACM Books 33. New York: Association for computing machinery, 2020.
  • “RDF 1.2 Schema,” accessed January 11, 2025, https://www.w3.org/TR/rdf12-schema/#ch_class.