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RDF::Reasoner

A partial RDFS/OWL/schema.org reasoner for RDF.rb.

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Description

Reasons over RDFS/OWL vocabularies and schema.org to generate statements which are entailed based on base RDFS/OWL rules along with vocabulary information. It can also be used to ask specific questions, such as if a given object is consistent with the vocabulary ruleset. This can be used to implement SPARQL Entailment Regimes and RDF Schema entailment.

Features

  • Entail rdfs:subClassOf generating an array of terms which are ancestors of the subject.
  • Entail rdfs:subPropertyOf generating an array of terms which are ancestors of the subject.
  • Entail rdfs:domain and rdfs:range adding rdf:type assertions on the subject or object.
  • Inverse rdfs:subClassOf entailment, to find descendant classes of the subject term.
  • Inverse rdfs:subPropertyOf entailment, to find descendant properties of the subject term.
  • Entail owl:equivalentClass generating an array of terms equivalent to the subject.
  • Entail owl:equivalentProperty generating an array of terms equivalent to the subject.
  • domainCompatible? determines if a particular resource is compatible with the domain definition of a given predicate, based on the intersection of entailed subclasses with the property domain.
  • rangeCompatible? determines if a particular resource is compatible with the range definition of a given predicate, based on the intersection of entailed subclasses or literal types with the property domain.
  • adds entail and lint commands to the rdf command line interface

Domain and Range entailment include specific rules for schema.org vocabularies.

  • A plain literal is an acceptable value for any property.
  • If resource is of type schema:Role, resource is domain acceptable if any other resource references resource using the same property.
  • If resource is of type schema:Role, it is range acceptable if it has the same property with an acceptable value.
  • If resource is of type rdf:List (must be previously entailed), it is range acceptable if all members of the list are otherwise range acceptable on the same property.

Limiting vocabularies used for reasoning

As loading vocabularies can dominate processing time, the RDF::Vocabulary.limit_vocabs method can be used to set a specific set of vocabularies over which to reason. For example:

RDF::Vocabulary.limit_vocabs(:rdf, :rdf, :schema)

will limit the vocabularies which are returned from RDF::Vocabulary.each, which is used for reasoning and other operations over vocabularies and terms.

Examples

Determine super-classes of a class

require 'rdf/reasoner'

RDF::Reasoner.apply(:rdfs)
term = RDF::Vocabulary.find_term("http://xmlns.com/foaf/0.1/Person")
term.entail(:subClassOf)
  # => [
    foaf:Agent,
    http://www.w3.org/2000/10/swap/pim/contact#Person,
    geo:SpatialThing,
    foaf:Person
  ]

Determine sub-classes of a class

require 'rdf/reasoner'

RDF::Reasoner.apply(:rdfs)
term = RDF::Vocab::FOAF.Person
term.entail(:subClass) # => [foaf:Person, mo:SoloMusicArtist]

Determine if a resource is compatible with the domains of a property

require 'rdf/reasoner'
require 'rdf/turtle'

RDF::Reasoner.apply(:rdfs)
graph = RDF::Graph.load("etc/doap.ttl")
subj = RDF::URI("https://rubygems.org/gems/rdf-reasoner")
RDF::Vocab::DOAP.name.domain_compatible?(subj, graph) # => true

Determine if a resource is compatible with the ranges of a property

require 'rdf/reasoner'
require 'rdf/turtle'

RDF::Reasoner.apply(:rdfs)
graph = RDF::Graph.load("etc/doap.ttl")
obj = RDF::Literal(Date.new)
RDF::Vocab::DOAP.created.range_compatible?(obj, graph) # => true

Perform equivalentClass entailment on a graph

require 'rdf/reasoner'
require 'rdf/turtle'

RDF::Reasoner.apply(:owl)
graph = RDF::Graph.load("etc/doap.ttl")
graph.entail!(:equivalentClass)

Yield all entailed statements for all entailment methods

require 'rdf/reasoner'
require 'rdf/turtle'

RDF::Reasoner.apply(:rdfs, :owl)
graph = RDF::Graph.load("etc/doap.ttl")
graph.enum_statement.entail.count # >= graph.enum_statement.count

Lint an expanded graph

require 'rdf/reasoner'
require 'rdf/turtle'

RDF::Reasoner.apply(:rdfs, :owl)
graph = RDF::Graph.load("etc/doap.ttl")
graph.entail!
messages = graph.lint
messages.each do |kind, term_messages|
  term_messages.each do |term, messages|
    options[:output].puts "#{kind}  #{term}"
    messages.each {|m| options[:output].puts "  #{m}"}
  end
end

Command-Line interface

The rdf command-line interface is extended with entail and lint commands. Entail can be used in combination, with serialize to generate an output graph representation including entailed triples.

Dependencies

Change Log

See Release Notes on GitHub

Mailing List

Authors

Contributing

  • Do your best to adhere to the existing coding conventions and idioms.
  • Don't use hard tabs, and don't leave trailing whitespace on any line. Before committing, run git diff --check to make sure of this.
  • Do document every method you add using YARD annotations. Read the tutorial or just look at the existing code for examples.
  • Don't touch the .gemspec, VERSION or AUTHORS files. If you need to change them, do so on your private branch only.
  • Do feel free to add yourself to the CREDITS file and the corresponding list in the the README. Alphabetical order applies.
  • Do note that in order for us to merge any non-trivial changes (as a rule of thumb, additions larger than about 15 lines of code), we need an explicit public domain dedication on record from you, which you will be asked to agree to on the first commit to a repo within the organization. Note that the agreement applies to all repos in the Ruby RDF organization.

License

This is free and unencumbered public domain software. For more information, see https://unlicense.org/ or the accompanying {file:UNLICENSE} file.