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Questions tagged [linked-data]

Linked Data refers to a set of best practices for publishing data on the Web under the Semantic Web standards (RDF, SPARQL, etc.). Please consider asking your question on https://opendata.stackexchange.com, if your question is not closely related to programming or is related to a particular Linked Data dataset.

T. Berners-Lee outlines four principles of linked data in his "Linked Data" note:

  1. Use URIs as names for things
  2. Use HTTP URIs so that people can look up those names
  3. When someone looks up a URI, provide useful information, using the standards (RDF*, SPARQL)
  4. Include links to other URIs, so that they can discover more things
324 questions
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What is the difference between dublin core terms and dublin core elements vocabularies

There's 2 Dublin Core vocabularies DC terms and DC elements. They define almost the same classes and properties. So what is the key differences between them, and when to use each one.
Wisamx
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units of measurement in owl and rdf

I'm creating linked data of materials and their physical properties, and I'm having trouble with setting units for certain properties. My individual material :AlMg3 has some mechanical properties like: :AlMg3 prop:hasTensileStrength "300" . :AlMg3…
Gem
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Problem when trying to reuse external terms using MIREOT Protégé Plugin

I have tried to reference external vocabulary using MIREOT Protégé Plugin. The external ontology is located in this link : http://purl.allotrope.org/voc/afo/REC/2018/07/afo (TTL File : http://purl.allotrope.org/voc/afo/REC/2018/07/afo.ttl). The…
Zakariae Aloulen
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SPARQL: How to obtain label in available languages if first option is not available

If a Wikidata resource returned by my query has no available label in the language I filtered for I obtained an empty cell. SELECT * WHERE { ?country wdt:P31 wd:Q6256. ?country rdfs:label ?country_name FILTER(LANG(?country_name) =…
CptNemo
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Good SPARQL query to find all triples with a resource as subject or object

I need to find all triples on DBpedia where http://dbpedia.org/resource/Benin is a subject or object. This query gives me the output that I want in a format that works the best for me (just three variables and no blank spaces): PREFIX :…
kurious
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Content negotiation using mod_rewrite / RewriteCond rules

I have a use case is to host a set of files (same RDF content with different serialization formats such as RDF/XML, Turtle, and JSON-LD) in Github pages and use a w3id URL as a permanent identifier. Further, I want to have content negotiation on…
Nandana
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What do the parameters of DBpedia Spotlight mean?

I am interested in using DBpedia Spotlight. However, we need to insert a value to the two parameters confidence and support. What do these two parameters really mean? I want to identify the significant, prominent n-grams in the text. In that case,…
J Cena
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RDFlib: Add triples to graph in bulk

I am parsing triple files and adding the triples into my local triplestore. Code Snippet: graph = ConjunctiveGraph('Sleepycat') graph.open("mytriplestore", create=False) g = Graph() g.parse("filename.ttl", format="ttl") for t in g: …
RDangol
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Why multiple URLs for a single wikidata concept?

Each item or property of wikidata has a persistent URI that you can obtain by appending its ID. For example, the property P1566 (representing GeoNames ID) has the following URI http://www.wikidata.org/prop/direct/P1566 You can also access to this…
Jane Foster
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Why use owl:Restriction as own:EquivalenceClass's property?

I just start to learn Semantic Web and have a question about restriction class. I dug a while but haven't found any answer yet.. Any help would be much appreciated! From text book, I see examples of define restriction class, they are all about to…
Charles Chow
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How can I tell if a resource/entity is a class or instance

In RDF/RDFS/OWL, how can I tell if an entity is an purely an instance or also a class? I understand that class entities are also instances, since they are instances of the "class" entity and subclasses of other classes. However, I believe some…
LazerSharks
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Use a numeric value as string value in SPARQL

Is possible to use somehow a numeric value as a string value in a SPARQL query? For instance, consider the following RDF data, query, and desired result: Knowledge base @prefix gr: . @prefix xsd:…
ffa
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How to get intersection-like behavior with SPARQL 1.1's VALUES?

Using SPARQL 1.1's values, the following query returns all predicates with Einstein or Knuth as the subject (along with their labels). PREFIX dbp: SELECT DISTINCT ?sub ?outpred ?label { VALUES ?sub {…
kdbanman
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In JSON-LD, is it possible to extend a context?

I have a JSON-LD document. { "@id": "VDWW1LL3MZ", "first_name": "Vincent", "last_name": "Willems", "knows":["MartyP"], "@context": { "foaf": "http://xmlns.com/foaf/0.1/", "first_name": "foaf:givenName", "last_name":…
Maarten
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What is the proper value representation of a schema.org/polygon when used in JSON-LD?

The data representation I will try to use for a RESTful API is JSON-LD and the vocabulary I intend to use are those from schema.org. In the vocabulary schema.org/GeoShape, it says that polygons are expected to be on text format but it doesn't…
Abel Callejo
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