Re: MISC: Internet Media Type registration: proposed TAG finding

[Graham Klyne]

> At 04:13 PM 5/24/02 -0500, Dan Connolly wrote:
> >That seems counter to common sense. That seems like saying
> >an IOU document
> >
> >         "I owe you one dollar"
> >
> >doesn't mean that I could pay you with 4 quarters, since
> >the relationship between a dollar and quarters isn't
> >specified in the IOU.
>
> I think that's exactly right, even if it is counter to common sense.
>
> In the absence of some *additional* information that 4 quarters are
> equivalent to a dollar for the purposes of settling a debt, I'd say a
> settlement with 4 quarters is not justified by the above statement.
>
> (So we have some common background facts, contexts maybe, ... but that's
> another discussion.)
>
> ...
>
> [later]
>
> I see you've already responded to a similar comment:
>
> >Hmm... that's one way to think of 'RDF inferences'.
> >It's not one that appeals to me.
>
> It seems to me you're introducing some new concept here that has not been
> discussed, and is certainly not part of RDF as currently defined.
>
> I've seen this kind of debate before, but I really had no idea that folks
> would seriously want to claim that without some explicit expression from
> some source that four quarters are equivalent to a dollar, that an RDF
> reasoner could conclude that a payment of four quarters would discharge
the
> IOU.
>

Oh-oh.  An unwarranted assumption has surfaced- the kind that slips in
easily.  There seems to be an assumption that the "dollar" means a dollar
bill (and therefore not four quarters). But that was never stated anywhere.
In fact, we don't really know what "one dollar" is, given just the IOU
statement in the example.  Presumably it would be defined somewhere else.
If it means "a monetary amount equal to $1.00", then four quarters would be
fine (if we knew enough about quarters somehow).

Without the "common background facts", we have no idea what to do with the
"one dollar", except possibly to compare it to some other balance (provided
we know that we can separate "dollar" from the "one" for numeric purposes.
We certainly cannot conclude that payment of one dollar bill will be
accepted but payment of four quarters will not.  Nor can we conclude that
both will be accepted, nor yet that a dollar bill will be.

This level of background knowledge goes beyond the capabilities of RDFS to
express, I think.

Cheers,

Tom P

Received on Saturday, 25 May 2002 17:17:35 UTC