My notes from 2020 about mappings to Wikidata:

It seems that in Wikidata, "exact match" is preferred, though in SKOS, exact match is transitive: if A is an exact match to B and B is an exact match to C then A and C are exact matches. It didn't seem to us that exact match was fitting for our mappings so we searched for alternate properties.

The possible mapping predicates:

• P2888 Exact Match https://www.wikidata.org/wiki/Property:P2888 . For example, see generic query and Joachim's query for Wikidata properties mapped to Schema.org

• P1709 Equivalent Class https://www.wikidata.org/wiki/Property:P1709 . For example, see Query:WDItems_mapped:DcClass.

• P2235 External Superproperty https://www.wikidata.org/wiki/Property:P2235 .

• P2236 External Subproperty https://www.wikidata.org/wiki/Property:P2236 .

• P1628 Equivalent Property https://www.wikidata.org/wiki/Property:P1628 . See also Query:WDProperties_MappedDCProperty.

  • labels in multiple languages for DC properties, alongside Wikidata equivalents
  • definitions in multiple languages for DC properties, classes, and datatypes, alongside Wikidata equivalents
  • definitions in multiple languages for (in this case just one) /elements/1.1/ property: dc:publisher, alongside Wikidata equivalent
  • definitions for /terms/ properties and classes, alongside Wikidata equivalents

Joachim suggested that mappings be reviewed by Usage Board but Liam Wyatt, a program manager for the Wikimedia Foundation, pointed out that this would formally not be necessary given that the purpose of Wikidata is to allow everyone to help and make changes.

We had some discussion of how Wikidata should be presented, eg, as a query (as listed above) or as a (three- or four-column) static table, such as a list of DC Properties Mapped to Wikidata Properties prepared by Grace Johnson. A query would show the current reality on Wikidata, while a static table would allow for notes and comments and would show what the Usage Board has determined the mappings to be.

If we were to build off of the queries listed above, we might want to make some improvements. For example, the query that lists Wikidata properties mapped to DC properties includes items as well as properties; a filter could be added to correct this mistake.

A table could be hosted on the page Wikidata:Dublin_Core.

More fundamentally, would the mappings live on Wikidata as property values, where the community can edit, or would we put them onto a page where only DCMI could edit?

Note that in July 2020, we decided to prioritize mappings to Schema.org over mappings to Wikidata.