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RE: Units (inches and centimetres, etc)

From: Graham Klyne <gk@ninebynine.org>
Date: Mon, 16 Jun 2003 18:21:01 +0100
Message-Id: <5.1.0.14.2.20030616180007.02f4a9e0@127.0.0.1>
To: <danny666@virgilio.it>, "RDF interest group" <www-rdf-interest@w3.org>

I think we're in considerable agreement -- I maybe wasn't clear enough.

My suggestion was that just that the arithmetic *vocabulary* as implemented 
by CWM be written up so that it's easier for a community of use to build 
up.  Any problems would then get identified and could be folded into a 
subsequent standardization process.

I suggested the CWM vocabulary because it exists, and see no point in 
inventing another one.  If there's another candidate, then by all means 
consider that.  Or if there's a real problem with CWM's vocabulary, let's 
know about it.  I think a fair number of people will copy CWM's vocabulary 
anyway, as has happened with predicates like log:implies and friends.

(In general, I wouldn't especially advocate standardizing vocabularies, but 
arithmetic seems to be sufficiently fundamental... it's difficult to do 
anything seriously without getting some level of arithmetic involvement.)

As for the service aspect, I think that smacks too much of computation, 
where RDF is about expressing truths.

Ultimately, as far as RDF is concerned, property/ies indicates 
relationship/s between values.  Whether those relationships are 
defined/presented in terms of the result of a well-known service 
(multiplication), or in terms of a mathematical description of the 
properties of such a service (e.g. 0*x=0, 1*x=x, x*y=y*x, succ(x)*y=x*y+y, 
etc) doesn't matter for that purpose, as long as the semantic 
interpretation applied yields the expected truths and non-truths.  When 
these relationships are used in an inference process, then you may need 
some "service" to actually perform evaluations.

The property URIs simply identify the relations;  in performing inference, 
it's the inference engine's responsibility to apply processes (services) 
that are consistent with those relations.

#g
--

At 18:18 16/06/03 +0200, Danny Ayers wrote:
> > This suggests to me that we don't really need anything new that isn't
> > already being done.  There's a lot of activity devoted to the development
> > of rules [2] [3].  It seems that there already exists a design for RDF
> > properties dealing with relations based on arithmetic operations [1],
> > though I could see a case for making that work a little more
> > "forceful" --
> > e.g. by publication as a W3C Note, with a view to taking it to the
> > recommendation track in future RDF working groups.
>
>I think cwm is wonderful, but I'm not sure how far it should be considered a
>role model. Being able to plugin a procedure at the drop of the hat is
>sweet, but unless that procedure is made explicit then everything could get
>very shaky. Being able to call on a reproducible algorithm/process/service
>to carry out a conversion is one thing, having it be a black box is another.
>Personally I'd favour drawing a line in the sand around simple comparisons
>(==, > etc) applied to typed literals which could form a little package of
>quasi-builtins for use with rules. Where any f beyond this is needed then I
>think this would be best viewed as a service, even if it is carried out
>locally as Chaals suggested.

-------------------
Graham Klyne
<GK@NineByNine.org>
PGP: 0FAA 69FF C083 000B A2E9  A131 01B9 1C7A DBCA CB5E
Received on Tuesday, 17 June 2003 04:48:26 GMT

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