◆ Semantic Web Catalogue

Design issue

Query & validation

How do we ask and check?

tension
Open world against closed world: a missing fact is unknown, or it is false.
also
Access, Querying, Constraints
scheme
design issues

Threads (2)

Long-running problems under this issue, told step by step. All threads.

  • Unknown or false? 1978–2026 largely settled 8 steps

    When a fact is missing, is it unknown or false, and how do you check data in a world that assumes it is merely unknown?

  • Querying a web, not a database 2008–2025 open 7 steps

    Can you query data spread across thousands of independent servers as if it were one database?

Who answered it

This issue's row of the map: which traditions' works mainly answer it, and the earliest from each.

traditionworksearliest
Hypertext
Knowledge representation 2 On Closed World Data Bases 1978
Databases 3 On Closed World Data Bases 1978
Machine learning 4 GraphRAG 2024
Web standards 8 SPARQL 2008
Search 3 GraphQL 2015
Social web
Open knowledge
Decentralized web
Libraries, archives and museums
Life sciences
Media
Geospatial 1 GeoSPARQL 2012
Commerce and supply chain
Government and law
Finance
Industry and engineering

6 of 17 traditions have taken up this question as a work's main issue; a work in several traditions counts in each. Same counts as the full map.

Timeline

Works on this question, its main or a secondary one, each shown once in date order; filter by tradition to follow one community. Bars run from start to end where both are known; marks people, projects and organizations still active. 6 entries have no date and are not shown. Hover over or focus an entry to draw its links. Scroll sideways, or use the decades above.

Lineage (18)

Works whose main question this is, by type, oldest first.

Concepts 3

  • GraphRAG 2024 concept technique

    Retrieval-augmented generation in which a language model answers from a knowledge graph built over the source texts, rather than from isolated text chunks.

  • Open-world assumption concept principle

    The rule that a fact missing from the data is unknown, not false. RDF and OWL assume it, unlike most databases.

  • Retrieval-augmented generation concept technique

    Technique in which a language model first retrieves relevant documents or data and then generates its answer from them.

Writings 6

Standards 8

  • SPARQL 2008 standard ★ seminal

    Query language for RDF data, a W3C Recommendation since January 2008; SPARQL 1.1 followed in 2013.

  • GeoSPARQL 2012 standard ★ seminal

    OGC standard, version 1.0 from 2012 and 1.1 from January 2024, that adds a vocabulary for geometries to RDF and spatial functions and relations to SPARQL, so queries can ask what is within, near or touching what.

  • SPARQL 1.1 2013 standard

    Second version of SPARQL, adding updates, aggregates, subqueries and federated queries; a W3C Recommendation since March 2013.

  • GraphQL 2015 standard

    Query language for web APIs developed at Facebook from 2012 and published in 2015; it lets a client ask for exactly the JSON it needs, and became the common choice where Linked Data APIs were not adopted.

  • SHACL 2017 standard ★ seminal

    W3C language for validating RDF data against shapes, closer to schema checking than to OWL's open-world reasoning; a Recommendation since July 2017.

  • GQL 2024 standard

    ISO standard query language for property graphs, published in April 2024 and partly derived from Neo4j's Cypher; the property-graph counterpart to SPARQL.

  • Model Context Protocol 2024 standard

    Open protocol introduced by Anthropic in November 2024 for connecting AI models to external tools and data sources; donated to the Linux Foundation's Agentic AI Foundation in December 2025.

  • SHACL 1.2 2025 standard

    Revision of SHACL by the W3C Data Shapes Working Group, in drafts since March 2025, adding modules for node expressions, rules, user interfaces, profiling and, from September 2026, inference rules that derive new triples from existing ones.

Projects 1

  • Google Dataset Search 2018 project

    Search engine for datasets that indexes schema.org Dataset descriptions published on the Web.

Also bears on this (13)

Concepts 4

  • Relational model 1969 concept formalism

    Model of data as relations, that is tables of rows with named columns, queried by declarative operations on whole sets; proposed by E.F. Codd and the basis of SQL databases.

  • Description logic concept formalism

    Family of decidable logics for describing concepts and their relations; the formal basis of OWL.

  • Entailment and inference concept formalism

    Deriving facts that follow from stated ones plus a schema or ontology, for example that a member of a subclass is also a member of its superclass.

  • Triplestore concept technique

    Database built to store RDF triples and answer SPARQL queries; Virtuoso is one example.

Writings 6

Standards 1

  • Lexicon standard

    AT Protocol's schema language for records, API endpoints and event streams. Each schema is a JSON file named by a reverse-DNS identifier (NSID); it resembles JSON Schema and OpenAPI rather than RDF vocabularies.

Projects 2

  • Virtuoso 1998 project

    OpenLink Software's database server for SQL and RDF data, used to publish DBpedia and many other Linked Data sets.

  • Semantic MediaWiki 2005 project

    Extension to MediaWiki that lets wiki pages carry typed, queryable data annotations.

People and organizations (28)

Linked to works on this question; the number counts those works.

World Wide Web Consortium (5) · Andy Seaborne (2) · Eric Prud'hommeaux (2) · Natasha Noy (2) · Anthropic · Claudio Gutiérrez · Dan Brickley · Darren Edge · David Soria Parra · Dimitris Kontokostas · Google · Harold Solbrig · Holger Knublauch · ISO · John Herring · Jorge Pérez · José Emilio Labra Gayo · Justin Spahr-Summers · Krzysztof Janowicz · Marcelo Arenas · Matthew Burgess · Matthew Perry · Meta Platforms · Open Geospatial Consortium · Raymond Reiter · Simon Cox · Steve Harris · Timo Homburg