Simplify bf:geographicCoverage and bf:temporalCoverage, to bf:covers

[sfolsom]

Justification: The class and predicate pairs are redundant; specifically, a work covers an object, and the type of object does not need to be repeated in the predicate. We recommend a single predicate, bf:covers, and inverse bf:coveredIn.

Also, we recommend removing the domain Work, since other types of resources, such as ExhibitionEvents, can have coverage.

This recommendation helps address current inconsistencies with the way the two existing coverage properties behave. The range of bf:geographicCoverage is bf:GeographicCoverage, even though bf:Place should be sufficient. bf:temporalCoverage is a datatype property even though bf:Temporal exists as an entity. If bf:covers is created, the range should be open to allow for use with bf:Place (bf:GeographicCoverage isn't needed) and bf:Temporal.

[This recommendation was made on behalf of the LD4P Art & Rare Materials BIBFRAME Ontology Extension (https://github.com/LD4P/arm).]

[melanieWacker]

The PCC Task Group on Sinopia Application Profiles made a recommendation in its final report (https://www.loc.gov/aba/pcc/taskgroup/Sinopia-Profiles-TG-Final-Report.pdf -- See page 15) that also relates to this issue:

Change bf:temporalCoverage from a Data Property to an Object Property

The data property bf:temporalCoverage should be changed to an object property (range
of rdfs:literal should be removed from bf:temporalCoverage, and add a class for
bf:TemporalCoverage)
The creators of BF originally made this a literal, probably because of a seeming lack of a
controlled vocabulary. Such vocabularies do exist however, at least in part (e.g., FAST,
Wikidata), and BF should allow for their use while still permitting use of strings.
Based on the report, PoCo voted on Dec. 18, 2020 to support this recommendation.