Re: [Graphs] g-text equivalence

On Mon, 2011-03-21 at 09:24 +0000, Andy Seaborne wrote:
> 
> On 20/03/11 00:16, Sandro Hawke wrote:
> > On Sat, 2011-03-19 at 19:02 -0500, Pat Hayes wrote:
> >> On Mar 18, 2011, at 3:56 PM, Sandro Hawke wrote:
> >>
> >>> On Fri, 2011-03-18 at 19:22 +0000, Andy Seaborne wrote:
> >>>>
> >>>> Is g-snap->g-text is just a function of the content type?
> >>>
> >>> Well, probably, for our purposes, I think so.
> >>>
> >>> There's a trivial case where it's not: the  arbitrary non-semantic
> >>> variability in serialization, eg whitespace.  So, some notion of
> >>> equivalence class of g-texts may be important.
> >>
> >> Can't we simply *define* g-texts to be equivalent under such trivial variations? It is our notion, after all.
> >
> > I'm not quite sure what you mean.  I think it's important the g-text be
> > a subclass of character or byte strings, so *equality* is string
> > equality.  For equivalence, yes, it seems like there's a simple and
> > obvious meaning of equivalence, but I don't know how to formalize it,
> > and I maybe it's not that quite that simple, for example:
> >
> > g-text t1: '_:x<http://www.w3.org/2000/01/rdf-schema#comment>  "Hello"'
> > g-text t2: '_:x<http://www.w3.org/2000/01/rdf-schema#comment>  "Hello"'
> > g-text t3: '_:y<http://www.w3.org/2000/01/rdf-schema#comment>  "Hello"'
> >
> > I think all of the are equivalent, but the equivalence of t1 and t2
> > (where the difference is just whitespace), seems somewhat different from
> > that between either of them and t3 (where the difference is in blank
> > node labeling).
> >
> > Should we just define a single standard "equivalence" of g-texts, or do
> > we need to allow room for there being several different kinds?
> >
> > Maybe the simple notion is "semantic equivalence" of g-texts, which I
> > might define as:   T1 and T2 are semantically equivalent iff the RDF
> > graphs produced by correct parsing of either of them are
> > indistinguishable.
> 
> Same value (value-equality = bNode-isomorphic set of triples), different 
> lexical forms.

Yes, I like that.

(but almost no one liked my suggestion to make it a real datatype.)

    - Sandro

>  Andy
>

Received on Tuesday, 22 March 2011 01:22:43 UTC