# Re: RDF Graphs

From: Hugh Glaser <hugh@glasers.org>
Date: Mon, 27 Oct 2014 23:04:03 +0000
Cc: Melvin Carvalho <melvincarvalho@gmail.com>, Pat Hayes <phayes@ihmc.us>, Semantic Web <semantic-web@w3.org>
Message-Id: <330D6DA9-6F32-4F39-AC12-24F290705A3F@glasers.org>
To: "Peter F. Patel-Schneider" <pfpschneider@gmail.com>
```Thanks Peter, that’s so helpful and succinct I can get rid of the history!

> On 27 Oct 2014, at 22:52, Peter F. Patel-Schneider <pfpschneider@gmail.com> wrote:
>
> I don't see why you should worry about an RDF graph not being exactly a simple graph.  There are lots of situations where modifiers are not subsective.
There are two reasons in Maths to use a term, I think.
One of them is to appeal to some pre-defined idea of the structure of things, so that the structure under discussion can be communicated quickly.
The other is to then appeal to a pre-existing body go knowledge about such structures.

> For example, a directed graph is not exactly a graph.
True, but all directed graphs are graphs; so using the term “graph in “directed graph” is helpful - it conveys structure by referring to previously understood things, and also allows me to lean on other Graph Theory results.
> What counts is that an RDF graph can be considered to like a sort of a graph, and it is.
Ah, so what “sort of graph”?
>
> The normal definition of a graph is a pair consisting of a set of nodes and a set of edges, so there is no problem with saying that an RDF graph is defined as a set of triples.
Only if you can establish the correspondence between a set of triples and a graph.
>
> Mathematics is full of cases where new notions are defined by modifying or extending old ones.
Yes, but usually only when helpful, as above.

Does it help to communicate what RDF looks like?
Well sometimes, but it also misleads, as I said.
Can it use existing results from Graph Theory? - well (I think?) only if it has certain, characteristics, which I think are actually quite unsual.
>
> peter
Cheers
Hugh
```
Received on Monday, 27 October 2014 23:04:28 UTC

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