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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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RML and FnO fails to run together

I am trying to use FnO functions in RML mapper (I like to do a string_split like here). This is how my folder looks like: I am executing java -jar "rmlmapper.jar" -m mapping-cuisines.ttl -o output-cuisines.ttl -s turtle However, when I try…
Azrion
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SPARQL query to get all the "leaf" classes / lowest level classes

I feel like I'm missing something rather obvious. I would like to query my graph so that I get all the "leafs", so any class that does not have a subclass. Basically, I need the inverse of rdfs:hasSubClass (I tried rdfs:superClassOf but it doesn't…
Robin
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Where is the “SPARQL” button in OntoRefine tab of GraphDB 9.5 Free Edition?

I wanted to transform tabular data into linked data. I was trying to use SPARQL construct to achieve this in GraphDB 9.5 Free edition. From the tutorials in GraphDb website it says "You can press the button SPARQL from the right top corner to…
slm12slm slm12slm
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A context for a top level index-only key in JSON-LD

I am trying to use JSON-LD to make a legacy JSON file machine readable. The JSON file in question has a top-level object with an item member referencing an object that contains the actual relevant data. { "item": { "id": "123", "name":…
aef
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Separating comma delimited text within a field using Python

I'm currently trying to convert a table into RDF using Python and attach the values from each cell to the end of a URL (eg E00 becomes statistics.data.gov.uk/id/statistical-geography/E00). I can do this for cells containing a single value using the…
Ian
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Understanding the structure of published skos concept schemes

There's something I don't understand about linked data, especially when it comes to skos concept schemes or the rdf data cube vocabulary. When I search for how to create and publish a skos cocept scheme I usually find something like this:…
nearwick
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Can't crawl RDF Data with Apache Nutch

I am trying to Crawl the DBpedia with Apache Nutch 1.15, but i'm having problems with parsing RDF files. On the parsing phase, i only get this message: **apache_nutch | Error parsing: http://dbpedia.org/data/Moscow.xml: failed(2,0): Can't…
gsjunior86
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How to get owl:sameas in dbpedia

I am using the following query to get wikidata ID from dbpedia page using owl:sameas. SELECT distinct ?wikidata_concept WHERE { owl:sameAs ?wikidata_concept FILTER(regex(str(?wikidata_concept),…
EmJ
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If the Giant Global Graph is implemented, how to search?

Different from knowledge graph, semantic data is decentralized. Does this mean that each search takes a lot of time to download semantic data? Does the search service require a lot of storage and memory space?
BlackGlory
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HTML element for importing semantic (linked) data

I want to include some semantic information of another website in my own site (for reusing the information instead of copying it). Is there a standardized HTML tag for this? (like it is possible with videos, images, etc.) As an example, let's take…
Kai Grunert
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Membership triple in Linked Data Platform Standard

Assume the existence of the following LDP resources & their representation: Prefixes: dex -> http://example.com/data/, schema -> http://schema.org/ an LDP RDF Source dex:ParkingFacility a ldp:RDFSource; foaf:primaryTopic <#it> . <#it> a…
Noor
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How to collect RDF triples for a simple knowledge graph?

When building a knowledge graph, the first step (if I understand it correctly), is to collect structured data, mainly RDF triples written by using some ontology, for example, Schema.org. Now, what is the best way to collect these RDF triples? Seems…
lee
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Using Raptor RDF Parser Toolkit to generate a FOAF rdfxml file

I want to write a C/C++ program using the Raptor RDF Parser Toolkit to generate the following output (checked with RDF Validator):
Vertexwahn
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How to parse large triple files?

Is there a way to breakdown large triple files (any format), so that they can be parsed? I am currently attempting to load a LOD data dump into a local triplestore using python (rdflib). Also, is there a better (in terms of scalability) alternative…
RDangol
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SPARQL query - why is fetching distinct predicates so slow?

While I was exploring some SPARQL queries I noticed that fetching distinct predicates is extremely slow but no such issues while fetching subjects or objects. I tested it with linkedgeodata and I ran the following queries at linkedgeodata's endpoint…
RDangol
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