Am 04.08.2011 17:40, schrieb Marko Rodriguez: > Yo, > >> I'm simply confronted with the question 'why do you use such a graph >> model and not another one based on graph classes'? >> Hence, I'm gathering pros and cons for the 'property graph' model. >> Why is an interface like the one of Neo4j provided this way and not in >> another (e.g. using graph classes). Is there any design or architectural >> decision we don't know, yet? >> The longer I think the more I come to the conclusion that important >> points are: object-oriented representation of a network, and related >> with that, an 'external' representation of the graph structure that is >> not bound to a graph class managing the access to the graph structure >> and the data stored in properties. >> All other points like performance, or representation of the graph >> structure, seem to be equivalent to text-book graphs (directed, >> undirected, etc.), like you already stated out. > Ah. I remember now -- you are interested in vertex typing (classes). I read > your paper on the topic. > > Here are my thoughts on the matter. In the world of RDF (which is has nice > clear separations), there is the data model (multi-relational graph), the > schema language (RDF schema), and the ontology language (OWL). Mixing these > layers into a single framework is deadly because you pigeonhole the > interpretation of the graph. For example, if you are into classes and type > hierarchies (and OO-based instantiations), then you are pigeonholing yourself > into close-world semantics and a taxonomical mind-set. Thats great for you if > you like that sort of thing---but what about others who wish, lets say to > explore evidential logics in which such strongly typed models are not > desired. This is also one of my problems with the RDF stack---while keeping > the layers separate, RDF/RDFS/OWL is seen as the only layer. And frankly, > description logics are not the only useful logics ( > http://arxiv.org/abs/0905.3378 ). Now map that to what you are saying about > property graphs and vertex typing. > > A property graph is a multi-relational graph data model. You can build logic > layers atop to implement your worldview as you see fit. It is the job of the > database to persist the structure and make it fast to traverse/query. It is > the job of the layers above to model and create meaning. Thanks for the information. I conclude: the property graph model is like it is due to the wish of flexibility and separation of concerns. >> Perhaps it is also a problem that the term 'property graph' isn't >> formally declared in some kind of scientific work and therefore widely >> unknown, isn't it? > Science is an industry claiming to be the ruler by which ideas are measured. > Ideas do not need science. However, science needs ideas. Do not be sucked > into the trap -- you will end up wearing a dusty suit, unhealthy, in some > stodgy dinning hall at some conference talking to others who think > publications make truth. And worst of all, you will be wearing a name tag. You're right! ;-) > Outz, > Marko. > > http://markorodriguez.com > _______________________________________________ > Neo4j mailing list > [email protected] > https://lists.neo4j.org/mailman/listinfo/user
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