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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: Ada & Ontology ( OWL,RDF, JSON, dot)
Date: Sat, 20 Jul 2013 00:56:38 -0500
Organization: Jacob Sparre Andersen Research & Innovation
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Date: 2013-07-20T00:56:38-05:00
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"Yannick Duchêne (Hibou57)" <yannick_duchene@yahoo.fr> wrote in message 
news:op.w0hmrfoqule2fv@cardamome...
Le Tue, 16 Jul 2013 02:35:16 +0200, Randy Brukardt <randy@rrsoftware.com>
a écrit:

> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote in message
> news:pgggo3irufxz$.mbvohwd9o6qd.dlg@40tude.net...
>> On Sun, 14 Jul 2013 23:36:22 -0700 (PDT), Peter Brooks wrote:
>>
>>>> Alternatively, is there a good Ada package for handling directed 
>>>> graphs?
>>>
>>> Well, it is difficult to provide a universal implementation of graphs.
>>> Usually, you would needs a custom implementation.
>>
>> Right. If your graph doesn't have any cycles (that is, it's a tree),[.]
>I believe this was an oops: an acyclic graph is not necessarily a tree.

I guess you're right. I was thinking that a "join" would have to necessarily 
cause a cycle, but that isn't true if both nodes are leafs and there are 
probably more cases as well. What I *was* thinking is that the multi-way 
tree that is contained in Ada.Containers supports a lot more structures than 
just the classic binary tree, and that many (maybe most?) acyclic graphs 
that you'll encounter in practice can be mapped into it. (I've never needed 
a more complex graph than a multi-way tree in any of my programs. YMMV.)

                                        Randy.