Thanks Marko, That's not exactly what I am looking for. I'd like to know what the name is of a relationship where there is only one unique combination of x and y in xRy for every relationship type R. Neo4j allows the creation of 2^64 relationships of the same type between the same two nodes. I'd like to define a type where there can be only one relationship of the same type between the same two nodes (eg. to limit the number of "FRIEND" relations between two Persons, since it is no use being friends with the same person multiple times, yet I'd like to allow a Person to have multiple "WINNER" relationships to a certain game (the count of the number of relationships indicating how often a person has been the winner of that game)). Is there any official name for a relationship type where the tuple (x, R, y) must be unique? Niels
> From: [email protected] > Date: Tue, 12 Jul 2011 10:27:04 -0600 > To: [email protected] > Subject: Re: [Neo4j] math question > > Hi, > > That is called a functional relationship. > > A functional relationship states that there is only one unique y in (xRy) for > every x. > - e.g. Social Security Number, Father, BornIn > > Inverse functional relationships are that there is a unique x in (xRy), for > every y. > > See ya, > Marko. > > http://markorodriguez.com > > On Jul 12, 2011, at 9:39 AM, Niels Hoogeveen wrote: > > > > > Does anyone know the proper mathematical name for a relationship with the > > following properties: > > For all x in X and y in Y it holds that if xRy and xR'y then R = R'. > > Example: > > There can be only one IS_PARENT relation from one person to another. > > Someone cannot be twice parent to the same person. > > There can be several IS_PRESIDENT_OF relations from one person to an > > organization. Someone can be president of an organizations from 1992-1997 > > and again from 2004-2008. > > Niels > > _______________________________________________ > > Neo4j mailing list > > [email protected] > > https://lists.neo4j.org/mailman/listinfo/user > > _______________________________________________ > Neo4j mailing list > [email protected] > https://lists.neo4j.org/mailman/listinfo/user _______________________________________________ Neo4j mailing list [email protected] https://lists.neo4j.org/mailman/listinfo/user
