Hi,
Also, R is bijective.
http://en.wikipedia.org/wiki/Bijection,_injection_and_surjection
Marko.
http://markorodriguez.com
On Jul 12, 2011, at 12:36 PM, Niels Hoogeveen wrote:
>
> 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
>>
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