Wikidata:WikiProject Ontology

WikiProject Ontology

The WikiProject Ontology is mainly about reaching deep into the nature of being, becoming, existence, and reality, and applying those insights during Wikidata's maintenance tasks. The more practical aims of the project are:

to improve the Wikidata ontology
to help editors understand the Wikidata ontology
to support a broad semantic interoperability between notable ontologies like DOLCE, BFO, SUMO, Lemon, RDA, etc.
to build consensus around the main branches of our core concept tree and how they relate to each other
to gain a deep understanding about the meaning of our upper ontology and to transfer this knowledge to others in practical terms

For specific subject areas, the class hierarchy and properties may be covered in detail on a WikiProject page devoted to that subject - for example WikiProject Books, WikiProject Names or WikiProject Chemistry.

A Wikidata Ontology Course was run during May and June 2025. The slides for all sessions of the course are available on the course page. Part of participating in the course was to set up a project related to the Wikidata Ontology. Information on the projects, many of which are continuing after the end of the course is available.

We have an active task force that is part of this WikiProject and works to improve the Ontology at Cleaning Task Force.

We are working to found a Mereology Task Force to improve the "Has part(s)" (P527) property. We want to do a project with a budget if we can.

Communications

Current and Past Efforts

Subpages

Modelling with classes in Wikidata: A discussion of how classes work in the Wikidata ontology

Classes: Summary of information on classes

Ontology Problems: A description of some of the problems in the Wikidata ontology. There are multiple pages under this page with more information about some of the problems.
Ontology Problems/instances of instances of physical object: Problems relating to instances of instances of physical object (Q223557) and a suggestion to improve the Wikidata constraint system.

Issues: Overview of the main ontology issues found in Wikidata at a discussion during WikidataCon 2021

Task Force: The Ontology Cleaning Task Force main page

BFO: Wikidata classes corresponding to BFO classes

Biocuration 2016: Information on the Biocuration conference in 2016

Mapping to External Ontologies: Beginnings of information on how to link the Wikidata Ontology to external ontologies

Ontology: A very short, partial description of ontologies

Most-general Classes: A list of the two most-general levels of classes in the Wikidata ontology

Second-order classes: An updating list of the direct instances of third-order class (Q24017465). Of very limited utility.

Third-order classes: An updating list of the direct instances of fourth-order class (Q24027474). Of extremely limited utility.

All Subpages including redirects

Tools

Wikidata Graph Builder: Makes it easy to visualize our ontology.
Classification.js : visualise the parent classes, reports problem on the WikiProject talk page, the classes an item is an instance of, detects loops in the class tree, detects and visualize class disjointedness violations issues.
metaclass-check.js This adds a warning text next to instance of (P31) statements on classes if their values are not metaclasses.

Detect classification issues

a WDQS query to check if two classes violates a disjoint union of statement

Participants

[+] Add yourself to the list

The participants listed below can be notified using the following template in discussions:
{{Ping project|Ontology}}

Melmakko (talk) 17:32, 4 November 2022 (UTC)
Tobias1984 (talk)
TomT0m (talk)
Bovlb (talk) 19:10, 21 October 2015 (UTC)
Peter F. Patel-Schneider (talk) 22:21, 23 October 2015 (UTC)
ArthurPSmith (talk) 15:51, 5 November 2015 (UTC)
Daniel Mietchen (talk) 20:53, 3 January 2016 (UTC)
Harmonia Amanda (talk) 22:00, 27 February 2016 (UTC)
Andrawaag (talk) 14:42, 13 April 2016 (UTC)
ChristianKl (talk) 16:22, 6 July 2016 (UTC)
Cmungall Cmungall (talk) 13:49, 8 July 2016 (UTC)
Cord Wiljes (talk) 16:53, 28 September 2016 (UTC)
Vladimir Alexiev (talk) 07:01, 24 February 2017 (UTC)
Pintoch (talk) 22:42, 5 March 2017 (UTC)
Fuzheado (talk) 14:43, 15 May 2017 (UTC)
YULdigitalpreservation (talk) 14:37, 14 June 2017 (UTC)
PKM (talk) 00:24, 17 June 2017 (UTC)
Andreasmperu
Jsamwrites (talk)
Finn Årup Nielsen (fnielsen) (talk) 12:39, 24 August 2017 (UTC)
Gamaliel (talk)
Horcrux (talk) 11:19, 12 November 2017 (UTC)
MartinPoulter (talk)
Bamyers99 (talk) 16:47, 18 March 2018 (UTC)
Dcflyer (talk) 07:50, 9 September 2018 (UTC)
Buccalon (talk) 14:08, 10 October 2018 (UTC)
Jneubert (talk) 06:02, 21 October 2018 (UTC)
Yair rand (talk) 00:16, 24 October 2018 (UTC)
ElanHR (talk) 22:05, 26 December 2018 (UTC)
Gabrielaltay
Liamjamesperritt (talk) 08:44, 21 June 2019 (UTC)
ZI Jony
Ivanhercaz (Talk) 11:07, 15 July 2019 (UTC)
Gaurav (talk) 22:39, 24 August 2019 (UTC)
SilentSpike (talk)
Tfrancart (talk)
TiagoLubiana (talk) 15:12, 2 December 2019 (UTC)
Albert Villanova del Moral (talk) 15:43, 6 February 2020 (UTC)
Clifflandis (talk) 15:10, 18 February 2020 (UTC)
Tinker Bell ★ ♥ 16:48, 23 March 2020 (UTC)
SM5POR
Toni 001 (talk) 11:03, 11 July 2020 (UTC)
Antoine2711 (talk) 17:22, 25 September 2020 (UTC)
Susanna Giaccai (talk) 07:22, 22 October 2020 (UTC)
So9q (talk) 10:17, 4 January 2021 (UTC)
Simon Cobb (User:Sic19 ; talk page) 18:29, 8 January 2021 (UTC)
Andrew Eells (User:AndrewEells ; talk page) 15:35, 7 April 2021 (UTC)
RShigapov 9:48, 8 April 2021 (UTC)
Mathieu Kappler (talk) 11:26, 6 September 2021 (UTC)
Loz.ross (talk) 13:52, 14 September 2021 (UTC)
Lectrician1 (talk) 19:29, 10 October 2021 (UTC)
Envlh (talk)
Amadalvarez (talk) 06:23, 1 February 2022 (UTC)
wd-Ryan (Talk) 23:13, 18 September 2022 (UTC)
Silver hr (talk) 22:44, 1 October 2022 (UTC)
EmericusPetro (talk) 22:43, 2 November 2022 (UTC)
Cord Wiljes (talk) 07:52, 30 November 2022 (UTC)
Photocyte (talk) 17:25, 17 March 2023 (UTC)
Danysan1 (talk) 13:29, 9 August 2023 (UTC)
Andrea Westerinen (talk) 23:33, 2 December 2023 (UTC)
Kepler Sticka-Jones (talk) 09:29, 25 December 2023 (UTC)
Egezort (talk) 17:23, 16 January 2024 (UTC)
Lepticed7 (talk) 10:41, 11 April 2024 (UTC)
Applsdev (talk) (contribs) 11:38, 31 July 2024 (UTC)
Ainali (talk) 07:34, 26 September 2024 (UTC)
CorraleH (talk) 04:33, 7 December 2024 (UTC)
King ChristLike (talk)
Margaret Warren(talk)
kind data
ErikaGuetti
Sarahmann2023 (talk) 15:55, 11 July 2025 (UTC)Sarahmann2023
Volvox (talk) 11:10, 15 July 2025 (UTC)
AHIOH (talk) 00:56, 14 November 2025 (UTC)

Inactive participants

(More than one year of inactivity)

Former Logo

Properties

Userbox

See: Wikidata:Userboxes

This user is a member of
WikiProject Ontology.

Resources

Giancarlo Guizzardi; João Paulo A. Almeida; Freddy Brasileiro; Victorio A. Carvalho (April 2016). "Applying a Multi-Level Modeling Theory to Assess Taxonomic Hierarchies in Wikidata" (PDF). Proceedings of the 25th International Conference Companion on World Wide Web: 975–980. doi:10.1145/2872518.2891117. Wikidata Q27037396.
Ege Atacan Doğan; Peter F. Patel-Schneider (17 October 2024), Disjointness Violations in Wikidata, 1, arXiv:2410.13707, doi:10.48550/ARXIV.2410.13707, Wikidata Q130629352