Re: Blank nodes must DIE! [ was Re: Blank nodes semantics - existential variables?]

>
> just because the same literal value is assigned to
> two nodes does not make them the same.  Is that literal value itself the
> "same" for both?
>

Isn't the answer *literally* yes 😂  Couldn't resist, sorry.
I'm really not an RDF expert though, so please just take my joke
lightheartedly. I appreciate all the dialogue.

Anthony

On Wed, Jul 8, 2020 at 9:00 AM Thomas Passin <tpassin@tompassin.net> wrote:

> On 7/8/2020 10:51 AM, Nicolas Chauvat wrote:
> > On Wed, Jul 08, 2020 at 08:28:05AM -0400, Thomas Passin wrote:
> >> the same points if they are not (and yes, I know that it could be
> considered
> >> a nice philosophical question whether they are "really" the same, but
> let's
> >> not enter in that here).
> >
> > Isn't it the whole point of the current (sub)discussion ?
> > Would you say that in the real world there are several different
> > literals that can have the value "hello" or would you say that two
> > literals that have the same value can be considered to be the same ?
>
> Here's what I am thinking of, and I'll talk about points, since that was
> the example I responded to (well, I think it was actually about the
> center of the circle, but never mind).  Think of a data point with a
> specific (x,y) value for the central location, one point of a set of
> data points, and let's say that that value is (1, 2).  The point might
> have had a value of (1.001, 1.999), but perhaps because of round-off
> error or some quantization procedure, the value recorded data tuple is
> (1.0, 2.0). or even (1, 2), by which I mean (int(1), int(2)).
>
> Now consider another data set, one of whose data points also has the
> data tuple (1, 2).  I am going to claim that those two data points,
> members of two different data sets, are not necessarily the same points
> even if they end up being represented by the same data tuple - (1, 2) in
> this case.  In physics, maybe the tuple values represent energy levels
> that change when a magnetic field is applied, but are degenerate when
> there is no field.  In this case they happen to be the same as each
> other because no field was applied to the one case, and in the other
> case the field would not have changed the value.
>
> You may say that this is a contrived case because the points in question
> originally were mathematical points, and they are characterized by pair
> of 2-D coordinates.  My point, though, is that in the context of an RDF
> graph (not to mention "real life"), any particular thing (or call it a
> resource, subject, or what have you) may have any number of additional
> complexities associate with it even if you don't happen to have included
> them in your graph.  That's the good old open world assumption.
>
> So unless you truly know that two point nodes with the same coordinate
> tuple of (1, 2) are the representing the very same thing, they may very
> well be different - in the context of RDF and the open world assumption.
>   It's not about a philosophical difference.
>
> Or put another way, just because the same literal value is assigned to
> two nodes does not make them the same.  Is that literal value itself the
> "same" for both?  In some software it might be - if it's been memoized,
> for example - but that's normally an implementation detail, not
> something fundamental.
>
> TomP
>
>
> > https://en.wikipedia.org/wiki/String_interning shows that some
> > programming languages store only one copy of immutable strings (or
> > immutable composite values/immutable structs in some cases) even when
> > these strings that have the same value are created at different places
> > and times in the program.
> >
> > Why would you call that question "philosophical" ? Do you mean it is
> > irrelevant ? If you think it is irrelevant, could you explain why ?
> >
>
>
>