Wikidata:WikiProject Ontology/Cleaning Task Force

This page serves as the main page for the ontology cleaning task force's efforts to clean up the Wikidata ontology.

The task force arose from a presentation (https://commons.wikimedia.org/wiki/File:Wikidata_Challenges_in_Semantic_Web_Community.pdf) by Andrea Westerinen at the 2023 Wikidata Data Quality Days (https://www.wikidata.org/wiki/Wikidata:Events/Data_Modelling_Days_2023)

Anyone interested in working to improve the Wikidata ontology is welcome to join the task force.

Scope

Just about any effort to improve the Wikidata ontology is considered in scope, ranging from theoretical analyses of the ontology, to techniques for reasoning in Wikidata, to implementation of tools that help improve the ontology, to documentation of problems with the ontology, to direct editing of the ontology. There is a welcome page that gives some background on the Wikidata ontology and the task force.

Areas of Interest

The task force has investigated several areas of the Wikidata ontology. Here are some of them and their current status:

• Disjointness: Ege and Peter looked at disjointness violations and made some changes that had very large effects. See Disjointness for more information.
• Class Order: Peter and Ege looked at class order and found a lot of problems. Peter is currently looking at class order problems triggered by an item being both an instance and a subclass of the same class. See Class Order for more information.
• Verb senses: A group has been figuring out how to best include more information about verb senses in Wikidata.
• Books: Kalliopi and Ege have been looking at the representation of books.
• Libraries: There have been comments on problems representing libraries. The task force may look at these problems, potentially in a broader sense.

If you are interested in anything related to cleaning the Wikidata ontology, feel free to add your interest above.

Meetings

The task force uses Google Meet for meetings, as described in the task force's calendar. Currently meetings are Tuesday at 11:30 am ET (currently UTC-4). Members of the task force are active in the Wikiproject Ontology telegram group.

Next meeting agenda

Interested parties should add agenda items for topics they wish to discuss. The default agenda has places for questions about the Wikidata ontology and reports on the current efforts. If there is significant work on any effort please add something to the agenda.

Tuesday, 6 October 2026, 11:30 EDT (UTC-4)

• Our meeting length is limited to 60 minutes by Google so meetings may be terminated abruptly.
  • This week the meeting will only be 30 minutes due to the Wikidata Platform team office hour.
  • Next week Peter will not be available.

• Welcome new members
  • If you can't make meetings please add information to this page about your interests and activities.

• Does anyone have activities to report?
  • If you have something you want to discuss you can edit this section

• Ongoing Topics
  • Wikidata birthday celebration
    • Is someone from the group interested in doing anything at a celebration?
  • Class order
    • Still lots of problems
    • Looking at product - lots of problems there
  • Mappings to other ontologies
    • Best practices
  • Organzation metaclasses cleanup

• Other topics

Tuesday, 13 October 2026, 11:30 EDT (UTC-4)

• Our meeting length is limited to 60 minutes by Google so meetings may be terminated abruptly.
  • This week Peter is not available.

Tuesday, 20 October 2026, 11:30 EDT (UTC-4)

• Our meeting length is limited to 60 minutes by Google so meetings may be terminated abruptly.

• DOLCE (Emilio)

Previous meeting notes

See Wikidata:WikiProject Ontology/Cleaning Task Force/Meetings for notes from prior meetings.

Participation

Anyone interested in working to improve the Wikidata ontology is welcome. Add your user identification below to join the group. Add issues that you are interested in or currently work on to the sections below.

Current and Past Participants

1. Peter Patel-Schneider
2. Lectrician1
3. Andrea Westerinen
4. PKM (talk)
5. Chris Mungall
6. Mahir256
7. Egezort
8. Alessandro Marchetti
9. Rosario Uceda-Sosa
10. Kind data
11. Margaret Warren
12. DutchTreat
13. Stefan Zipproth
14. Daniel Antal
15. User:PacmanD
16. Arlo Barnes (talk)
17. Epìdosis
18. JackKausch
19. Hanna Abi Akl

Wikidata Ontology Course

Peter and Ege ran a course on the Wikidata Ontology in May and June 2025.

The second offering of the course will be given in May and June 2026. For more information see the course page, above.

Current efforts and Information

See the Activities Page for information on some activities that have been done within the task force.

Related Information

There is a page on what might be done to improve the Wikidata ontology at https://www.wikidata.org/wiki/Wikidata:Ontology_issues_prioritization. This was a result of a survey of Wikidata users on what problems they encountered when using the Wikidata ontology.

https://www.wikidata.org/wiki/Wikidata:Tools/Enhance_user_interface#Classification.js is a useful tool to show parts of the Wikidata ontology.