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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
371 questions
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Jena Fuseki Vs Virtuoso

I am running same queries on Virtuoso and Jena Fuseki - A query on Virtuoso gave ResultRows=594890 while on Fuseki it gave the error of "page not responding". Also in many other cases, the fuseki could not execute the same queries which were done by…
Khan
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LDFlex filter by type

I'd like to use LDFlex to list all subjects within a document, of a certain type. data["https://example.com/mydocument.ttl"].subjects provides all the subjects in the document. It's possible in SPARQL to specify something like WHERE {?s a mytype};…
enigma
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Converting a CSV to RDF where one column is a set of values

I want to convert a CSV to RDF. One of the column of that CSV is, in fact, a set of values joined with a separator character (in my case, the space character). Here is a sample CSV (with header): col1,col2,col3 "A","B C D","John" "M","X Y…
lOlive
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Select all literals from a specific language in a SPARQL query

In a SPARQL query, it is possible to choose a language for each literal (and also strip the language tag): CONSTRUCT {?x dc:title ?stripped_title.} WHERE{ ?x rdfs:label ?title . FILTER (langMatches(lang(?title),"en")) BIND (STR(?title) AS…
dilvan
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What RDF patterns can be used to represent components and the percentage they make up?

I'd like to inventory my wine collection using RDF but am not sure how to specify that wine can contain percentages of several grape varietals. Below is an attempt to do so in Turtle syntax using rdf:bag. @prefix xsd:…
Kelly
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Preferred combination SPARQL

I am trying to write an elegant SPARQL that gives me one solution for multiple possible queries. I have a number of subjects and a number of predicates and I want to receive a single object. The existence of a single solution is very uncertain so I…
Wietse de Vries
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SPARQL query to get instances with only some and not all properties

Let say I have triples of the form uri:ObjA1 uri:propAA uri:Obj1A . uri:ObjA1 uri:propAA uri:Obj1B . uri:ObjA2 uri:propAA uri:Obj1A . uri:ObjA2 uri:propAA uri:Obj1B . uri:ObjA2 uri:propAA uri:Obj1C . Now, what I am trying to do is find all…
thisisshantzz
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Double values are truncated (rounded) in Virtuoso SRARQL results

I am using Virtuoso Opensource 7.2.4 and have a dataset which consists of some data, for example: @prefix xsd: @prefix geo: . @prefix ap:…
Nandana
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Aggregation of values in a given range (interval) with SPARQL?

Say in an RDF dataset, there are a set of values that range from 0 to 100 (for example, percentages). I want to count the number of values in a given range, for example, 100 - 90 | 90 - 80 | ... | 10 - 0. The output I expect looks like the…
Nandana
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SPARQL - Find objects with the most similar properties

Lets say there is a RDF DB of people and each of these people has many triples defining this person's friends (so many of 'person' x:hasFriend 'otherPerson'). How can I find people who have the most similar friends? I'm a novice at SPARQL and this…
Fabis
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Inference over linked data SPARQL endpoints

When querying some linked data SPARQL endpoints via SPARQL queries, what is the type of reasoning provided (if any)? For example, DBpedia SNORQL endpoint doesn't even provide the basic subclass inference (if A subClassOf B and B subClassOf C, then…
Median Hilal
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Schema.org clarification for JSON-LD representation and URIs

I'm trying to encode in JSON-LD the semantic information related to a website using Schema.org. The web site is very basic: it contains the home page, a gallery page with a list of images and the image detail page. Reading the different examples…
user9370976
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Rdflib.js, how to serialize the data into turtle (.ttl) format?

How can I serialize RDF in turtle using rdflib.js? There's not much documentation. I can use: Serializer.statementsToN3(destination); to serialize into the N3 format, but not much besides that. I've tried altering the aforementioned command to…
Fox
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Strings in Sparql

I'm playing around with DBPedia. With this query I get all people who were born in London: SELECT ?person WHERE { ?person dbo:birthPlace :London } But why I get an empty result when I execute this query? SELECT ?person WHERE { …
Evgenij Reznik
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How can I easily convert RDF triples to/from an idiomatic Java POJO business object?

I'm a Java developer just getting started with linked data/RDF. I can create triples, put them in a triple store, query them, etc, but it's very awkward. Most of my code is focused on the mechanics of RDF and I'd really like to work with this data…
Kaypro II
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