Good points and worth adding. Let me first finish the work I am doing now, which implements the current API and adds some methods that mirror the current API, then we can start looking at making things even niftier. Niels
> From: [email protected] > Date: Thu, 21 Jul 2011 20:37:52 +0200 > To: [email protected] > Subject: Re: [Neo4j] Hyperedges and Objects > > Perhaps we can also add to this enhanced API: > > * creation of nodes and rels with a initial map of properties, with optional > auto-indexing of some of those properties > * a getOrCreate method > * fluent, chained API for creating stuff in a readable language > * getRelationshipCount() > * some more that I forgot :) > > Michael, pulling his wishlist > > Am 21.07.2011 um 20:32 schrieb Niels Hoogeveen: > > > > > i made a start on this. It's not all too difficult to enhance relationships > > such that relationships can be created upon them, which is a first step > > towards supporting hypergraphs. In fact hypergraphs are more constrained > > than an enhanced graph that supports the creation of relationships on > > relationships. > > As it stands now, the enhanced graph can work as a drop-in replacement of > > the standard neo4j API and has enhanced methods that mirror the standard > > methods. > > I also added support for typed properties, such that methods like <T> > > getPropertyValue<PropertyType<T>> are possible where <T> is one of the data > > types supported by PropertyContainer. > > I will upload this within the next few days. > > Niels > > > > > > From: [email protected] > > To: [email protected] > > Subject: RE: [Neo4j] Hyperedges and Objects > > Date: Mon, 18 Jul 2011 17:59:08 +0200 > > > > > > > > > > > > > > > > > > I think a hypergraph would be an interesting collection to support in > > neo-graph-collections. If I find the time, I will make a start with it this > > week, unless there are of course other volunteers :wink: willing to do the > > lifting here. > > Niels > > > >> From: [email protected] > >> Date: Sat, 16 Jul 2011 23:37:48 +0200 > >> To: [email protected] > >> Subject: Re: [Neo4j] Hyperedges and Objects > >> > >> I completely agree, > >> > >> hyperedges and the accompanying traversers should be handled in a library. > >> As you probably know the traversal framework currently also uses the core > >> API under the hood to perform the traversals (and no black magic (yet)). > >> > >> So it should be fairly easy to take that approach/code and create a > >> library that abstracts the hyper-edge issues (creation, deletion, > >> traversal). The position semantics based approach sounds interesting. > >> > >> Would love to see that as community contribution. > >> > >> Cheers > >> > >> Michael > >> > >> Am 16.07.2011 um 23:08 schrieb Niels Hoogeveen: > >> > >>> > >>> The question is how much easier a traverser can become when there were > >>> dedicated hyper edges. In a binary relation it is fairly easy to define > >>> one end of the relation as the source and the other as the target (start > >>> and end node), > >>> but in n-ary relationships the roles of the attached nodes become more > >>> complicated. > >>> > >>> Suppose we have the GIVES relationship, where one attached node takes the > >>> role of subject (the giver), > >>> one node takes the role of direct object (the gift), and another node > >>> takes the role of indirect object (the recipient). > >>> To traverse such a graph, we need to know these different roles, > >>> otherwise we may end up traversing the wrong nodes. > >>> > >>> Suppose we the following statements: > >>> > >>> John gives Paul a servant. > >>> Paul visited Albania. > >>> Paul's servant visited Albania. > >>> > >>> We now want to know all people that received a gift from John and who > >>> visited Albania. > >>> > >>> Without properly denoting the roles in the ternary relationship stated by > >>> "John gives Paul a servant", > >>> the answer to the query may well be: Paul and Paul's servant. > >>> Both are persons, both have visited Albania and both are part of the > >>> GIVES relationship defined. > >>> > >>> When we have to define the exact roles of each part of an n-ary > >>> relationship for each traversal, > >>> it is just as complicated as defining a traversal based on binary > >>> relationships, > >>> where different relationship types denote the roles of each part of the > >>> n-ary relationship. > >>> > >>> If hyperedges were to be introduced, either as a library or in core, > >>> the entire notion of the graph and how traversals are performed need to > >>> be rethought. > >>> > >>> The concept of an edge as having a start and an end node doesn't > >>> translate well into the world of hyper edges. > >>> There is not necessarily a start node and an end node, > >>> instead there are various nodes that are distinctly attached to the hyper > >>> edge. > >>> > >>> One way to think about an edge in both the graph and in the hypergraph > >>> world is as a tuple. > >>> > >>> A binary relationship can be thought of as the tuple: > >>> > >>> (node1, node2, RelationshipType, Set(property)) > >>> > >>> A ternary relationship can be thought of as the tuple: > >>> > >>> (node1, node2, node3, RelationshipType, Set(property)) > >>> > >>> etc... > >>> > >>> Instead of marking a binary relationship as outgoing or incoming, we can > >>> use the position in the tuple to denote its role. > >>> We can say the first node in the tuple corresponds to the start node, and > >>> the second node in the tuple corresponds to the end node. > >>> Having two possible permutations relates to the two possible directions > >>> an edge can have. > >>> > >>> Position based definitions of relationships translate well into the > >>> domain of n-ary relationships, > >>> though the semantics of such relationships can easily become difficult. > >>> A ternary relationship already has 6 permutations for the attached nodes, > >>> while a 10-ary relationship has 3,628,800 possible permutations. > >>> > >>> It would be an interesting project to design a tuple-position-based > >>> traverser. > >>> For binary relationships it should have the exact same features as the > >>> current direction based traverser, > >>> but it would be possible to generalize that design to n-ary > >>> relationships. > >>> This can all be done as a libary. > >>> > >>> Only when perfomance can be really improved in core, does it make sense > >>> to request for native support. > >>> > >>> Niels > >>>> Date: Sat, 16 Jul 2011 19:31:22 +0200 > >>>> From: [email protected] > >>>> To: [email protected] > >>>> Subject: Re: [Neo4j] Hyperedges and Objects > >>>> > >>>> That's clear. Such mappings are more difficult to traverse since the > >>>> traverser has to know if there is such a hyper edge vertex. I'm > >>>> wondering if there is no need to provide an embedded solution for such a > >>>> transformation. Each user who is confronted with hyper edges has to > >>>> implement some kind of such mapping. It would be helpful, for example, > >>>> if each Neo4j relationship can manage hyper edges automatically and > >>>> provide an additional 'isHyper' method pointing out that there are > >>>> additional methods allowing to get all further incident nodes. This is > >>>> also a matter of performance. I think such a handling is implemented > >>>> most efficiently within the Neo4j engine. > >>>> > >>>> Best regards > >>>> > >>>> Norbert Tausch > >>>> > >>>> Am 16.07.2011 00:52, schrieb Niels Hoogeveen: > >>>>> Hyper edges can be emulated. > >>>>> Suppose you want to store the fact "John gives Pete a book". > >>>>> This is indeed a ternary relationship, which would call for an hyper > >>>>> edge. > >>>>> This fact can be stored as follows: > >>>>> Some act of giving --Giver-->JohnSome act of giving --Recipient--> > >>>>> PeteSome act of giving --Gift--> book > >>>>> N-ary relationships can generally be decomposed into N binary > >>>>> relationships, where a central node is used to used as a placeholder > >>>>> for the N-ary relationship. > >>>>> Complex types can either be stored into a byte array or if appropriate > >>>>> in multiple properties. > >>>>> > >>>>> > >>>>>> Date: Sat, 16 Jul 2011 00:04:15 +0200 > >>>>>> From: [email protected] > >>>>>> To: [email protected] > >>>>>> Subject: [Neo4j] Hyperedges and Objects > >>>>>> > >>>>>> Hi, > >>>>>> > >>>>>> is there a possibility to store hyper edges in Neo4j? Is there a plan > >>>>>> to > >>>>>> implement this? > >>>>>> > >>>>>> Will Neo4j get the ability to store complex types in addition to > >>>>>> primitve data types for properties of nodes and relationships? > >>>>>> > >>>>>> -- > >>>>>> Best regards > >>>>>> > >>>>>> Norbert Tausch > >>>>>> > >>>>>> _______________________________________________ > >>>>>> 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 > >>> > >>> _______________________________________________ > >>> 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 > > _______________________________________________ > Neo4j mailing list > [email protected] > https://lists.neo4j.org/mailman/listinfo/user _______________________________________________ Neo4j mailing list [email protected] https://lists.neo4j.org/mailman/listinfo/user
