One of the issues I discussed at my recent talk in the Art in Context: Identity, Ethics, and Insight symposium was the problem of representing anonymous artists in knowledge graphs. The solution that the Wikidata community has accepted is to associate a P170 (creator) claim with a somevalue
snak having a P3831 (object has role) qualifier value of Q4233718 (anonymous). In RDF, this corresponds to a blank node and Wikidata claims using somevalue
are represented by blank nodes in the Query Service.