Define terms "beginning group" and "ending group"

[nichtich]

The document says: "Ranges of periodical units are described by beginning and ending groups" without further defining this groups. The terms are also referred to later. As I understand, the beginning group of a chronology $X is the set of all literals $Y with $X ecpo:hasBegin $Y, right?

[cKlee]

Yes this is right.I did not define the beginning and ending group. Do you think this is necessary?

[cKlee]

I wonder how to define beginning and ending groups as classes and how to differentiate them from RunningChronology and ClosedChronology?

ecpo:EndingGroup a owl:Class ;
    rdfs:subClassOf [ 
        a owl:Restriction ;
        owl:maxCardinality "1"^^xsd:nonNegativeInteger ;
        owl:onProperty ecpo:hasEnd
    ] ;
    rdfs:subClassOf [
        a owl:Restriction ;
        owl:minCardinality "0"^^xsd:nonNegativeInteger ;
        owl:onProperty ecpo:hasBegin
    ] .

ecpo:BeginningGroup a owl:Class ;
    owl:equivalentClass ecpo:RunningChronology ;
    rdfs:subClassOf [ 
        a owl:Restriction ;
        owl:maxCardinality "0"^^xsd:nonNegativeInteger ;
        owl:onProperty ecpo:hasEnd
    ] ;
    rdfs:subClassOf [
        a owl:Restriction ;
        owl:minCardinality "1"^^xsd:nonNegativeInteger ;
        owl:onProperty ecpo:hasBegin
    ] .

ecpo:RunningChronology a owl:Class ;
    owl:equivalentClass ecpo:BeginningGroup .

ecpo:ClosedChronology a owl:Class ;
    owl:unionOf (ecpo:BeginningGroup ecpo:EndingGroup).

[nichtich]

If a beginning group is just the set of all literals used to define the begin of a particular Chronology, there is no need to define it as class. I'd prefer more informal, human-readable explanation instead of more formal OWL syntax.