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Elliotte Harold wrote:
> Hunsberger, Peter wrote:
>
>> I don't agree. Where are the graph serialization standards? Where are
>> the best practice algorithms for graph traversal? Where are the
>> standardized languages for graph transformation? Where are the "graph
>> databases"?
>
>
>
> I think we're talking past each other on two different levels here. I
> was talking about the generic principles of handling graphs (which are
> well understood, as are those for handling trees) and you were talking
> about common, agreed upon formats for data.
>
> I don't think there are any standardized formats for graphs, similar
> to what XML is for trees. It might be an interesting project to invent
> one. It might even be useful. I suspect it would look a lot like RDF,
> minus all the URI baggage.
>
> The graph databases do exist, though I'm hardly enough of an expert to
> point to one. The best practice algorithms are well-known too within
> the graph theory community, of which I am not a member so again I
> can't point to them for you, but they are out there. Ask a practicing
> mathematician for details, and then be prepared to listen for a while.
when i designed a graph based data base i only set up to specify the
vertices and edges. i noticed a couple of things from this. the graphs
can't be easily represented in 2 dimensions (let alone 1) (there's a
whole body of work on flattening graphs to n dimensions), but they can
be easily traversed. any application actually uses a tree with it's root
as one of the vertices. the edges have a nature of their own that
determines whether or not an edge can take part in a tree. cycle
detection is essential when constructing the tree. machine traversal is
relatively easy even if visualisation is hard (cf a klein bottle). etc.
there's some concept that the object-relational database (sort of an
oxymoron really) is a graph based data base as well. i had to introduce
an "alias" concept in the general sense to make trees out of graphs that
wanted to reference the same vertices, but in different contexts. graphs
can easily represent very complex sets of relationships - something
trees will never do. to me this means xml must struggle as application
or document complexity increases, so there will be a requirement for a
meta-xml (MXML?).
rick
>
> I don't know if there are any standardized languages for graph
> traversal. That might also make an interesting project.
>
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