The SIG decide 8-10 years ago to use E74 Group to model relations between persons. From a practical point of view this is very handy. A relation is simply an instance of E74 group of E21 Persons where the persons in question are members. The intention behind E74 Group is that the group as such can act as one unit. As Martin pointed out :"I could quite well imagine having a sort of more general Group describing a social bond that would not involve members potentially "acting as one" or one speaking for them. In that case, that Group would no more be "one Actor". (Martin Doerr 4/8/2014).
In prosopography (see for example http://snapdrgn.net/) and in social anthropology one may be interested in relations between persons not naturally acting as a single actor . For example, my great grandfather aunt (born in the end of 18th century) and I may be related but do not have the potential to acting as one actor. The excerpt from ULAN below, shows besides family relationships a student/teacher relationship. I would claim that it is not necessary so that a student and a teacher should be seen as members of a E74 Group. Still we need to be able to model such relations. It is of course possible to extend CRM with new properties for each relevant relationship. One may also extend CRM with a generic relationship property with a .1 E55 Type property indicating the kind of the relationship. The one need one generic property for binary relationships, one for trinary etc etc. A solution may be to introduce a single relationship group which is not a subclass of E39 Actor, but with the similar membership properties as E74. One may argue that (social) relationships are abstract entities originating in humans' minds. Therefore the class of such "relationship groups" should be a subclass of E28 Conceptual Object. A relationship is not a type but has a type. It is hardly a legal object(?) It could be a subclass of P89 Propositional Object? We need some discussion here. Chr-Emil ******************************** ULAN excerpts Christian Krohg Related People or Corporate Bodies: parent of .... Krohg, Per ................ (Norwegian painter, costume designer, and scenographer, 1889-1965) [500009787] spouse of .... Krohg, Oda ................ (Norwegian painter, 1860-1935) [500069715] student of .... Gude, Hans Fredrik .................. (Norwegian painter, 1825-1903) [500004718] student of .... Gussow, Karl .................. (German painter, 1843-1907) [500031129] student of .... Middelthun, Julius Olavus 1870-1871 .................. (Norwegian sculptor, 1820-1886) [500122010] teacher of .... Eiebakke, August 1886-1887 .................. (Norwegian painter, 1867-1938) [500093351] Oda Krohg Related People or Corporate Bodies: spouse of .... Krohg, Christian ................ (Norwegian painter, draftsman, and author, 1852-1925) [500011632] Per Krohg Related People or Corporate Bodies: child of .... Krohg, Christian .............. (Norwegian painter, draftsman, and author, 1852-1925) [500011632] teacher of .... Storstein, Aage .................. (Norwegian painter, 1900-1983) [500091511]
