Proposal for Requiring Save/Restore of Sets and Tags

[Tim Tautges]

With the current definition of set parent/child relations, you can embed not only directed graphs in the data model, but 
also general graphs.  In this case you'd use only one of the parent/child types of links, and two nodes in the graph 
linked by an edge would each have a parent link to the other.  Granted you'd need to be careful when traversing these, 
because of the inherent cycles, but at least you'd be able to represent them, in a part of the data model that is 
already fairly natural for many of the other queries on graph nodes, and for representing other types of (i.e. directed) 
graphs.

As to what you'd use them for, choose any application of undirected graphs on a mesh, e.g. maximal independent set, 
graph coloring, etc.

I agree that embedding these types of graphs into a data model that seems more geared to directed graphs is a stretch. 
But, in my view, we should keep the possibility of embedding general graphs in the data model, even if accessing those 
types of graphs is somewhat unnatural.

- tim

On 10/05/2010 12:56 AM, Carl Ollivier-Gooch wrote:
>
> To get a cycle, you've got to have this looping back on itself.
> Semantically, it makes sense, but it's (a) silly and (b) unlikely to
> occur except on purpose, in which case, why bother?
>
> Carl
>

-- 
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              Tim Tautges            Argonne National Laboratory
          (tautges at mcs.anl.gov)      (telecommuting from UW-Madison)
          phone: (608) 263-8485      1500 Engineering Dr.
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