Add P81a, P81b, P82a and P82b data properties about ecrm HOT 3 OPEN

I would like to support this request.

Some humanities projects are already referencing the Erlangen CRM when using these properties, even though they are not implemented in the Erlangen CRM.

In a CIDOC CRM technical paper Implementing the CIDOC Conceptual Reference Model in RDF (2020) Doerr and Light further specify the guidelines for P81a, P81b, P82a and P82b:

The range of the properties "P81 ongoing throughout" and "P82 at some time within" are
defined in the CRM as E61 Time Primitive. Instances of E61 Time Primitive are defined as
closed, contiguous intervals on the natural time dimension in which we live. “Closed” means
that the endpoints belong to the interval. “Contiguous” means that there are no gaps between
the endpoints in the interval (which holds for “intervals” in general).
The reason to describe time spans with inner and outer intervals is the existence of a very
efficient algebra for calculating resulting areas of determinacy and indeterminacy (Cowley &
Plexousakis 2000). Further, they are motivated by the British MIDAS Heritage standards
[https://en.wikipedia.org/wiki/MIDAS_Heritage] and easy to define in Relational databases.
Since the E61 Time Primitive of the CRM cannot be expressed in RDF directly, in the official
RDF implementation of the CIDOC CRM, we define four properties replacing P81 and P82
adequately using xsd:dateTime.

from ecrm.

The Russian labels are screwed, except for P81a. I reported that to the CRM SIG 5y ago.

from ecrm.

You're welcome to provide a domain ontology adding these. :)

from ecrm.