Dear Wolfgang,
I regard that the statement P7(x,y) ∧ P89(y,z) ⇒ P7(x,z) was never true,
and following the decision of the last SIG it does no more appear.
The oral explanation in the SIG that is causes a useless recursion
through the world was just an indication that it was nonsensical from
the beginning. In my understanding, it was a confusion taking an
inverse shortcut for a shortcut.
In my understanding, and actual scholarly practice, P7 expresses a
reasonable, NOT arbitrarily large, outer /approximation/ of the place
where something happened. The narrower the better.
Indeed, "we now say that we need to have an explicit statement that x
was within a place y and regard only the statements P7(x,z) to be true
or inferrable for all z between the spatial projection and y"
That is in the new FOL, isn't it?
Indeed,
"If I have a statement in my information system that, lacking more
precise information, a period such as the move of an object took place
somewhere in Europe, is P7 then automatically true for all places
between the spatial projection of the move and Europe but my information
system couldn't actually infer any additional P7 statement because it
doesn't know where the declarative place of the spatial projection is"
We should be aware that "approximation" has no equivalent in FOL. It has
a quality, which can be formalized by /metrics/. If you have some
background knowledge in topology, you may be familiar with the
respective concepts.
Automatically, the intersection of all yi, i=1...n of P7(x,yi)
constitutes the best approximation.
Best,
Martin
On 10/20/2022 3:12 PM, Wolfgang Schmidle via Crm-sig wrote:
Sorry, second attempt:
According to Christian-Emil's homework for issue 606, the reason to avoid the
statement P7(x,y) ∧ P89(y,z) ⇒ P7(x,z) was that it might create problems in
hypothetical information systems that are clever enough to traverse the graph
created by all P89 statements but not clever enough to not fill themselves up
with large amounts of deduced P7 statements.
If we accept this argument, do we still regard P7(x,y) ∧ P89(y,z) ⇒ P7(x,z) as
true based on the semantics of P7 and P89? Or do we now say that we need to
have an explicit statement that x was within a place y and regard only the
statements P7(x,z) to be true or inferrable for all z between the spatial
projection and y?
If the latter: If I have a statement in my information system that, lacking
more precise information, a period such as the move of an object took place
somewhere in Europe, is P7 then automatically true for all places between the
spatial projection of the move and Europe but my information system couldn't
actually infer any additional P7 statement because it doesn't know where the
declarative place of the spatial projection is?
Am 20.10.2022 um 13:56 schrieb Wolfgang Schmidle via
Crm-sig<crm-sig@ics.forth.gr>:
Quick question: According to Christian-Emil's homework for issue 606, the
reason to avoid the statement P7(x,y) ∧ P89(y,z) ⇒ P7(x,z) was that it might
create problems in hypothetical information systems that are clever enough to
traverse the graph created by all P89 statements but not clever enough to not
fill themselves up with large amounts of deduced P7 statements.
If we accept this argument, do we still assume that P7(x,y) ∧ P89(y,z) ⇒
P7(x,z) is true based on the semantics of P7 and P89? Or do we now say that we
need to have an explicit statement that x was within a place y and regard only
the statements P7(x,z) to be inferrable for all z the spatial projection and y?
If the latter: If I have a statement in my information system that, lacking
more precise information, an object is located (or the move of an object took
place) somewhere in Europe, is P7 then automatically true for all places
between the spatial projection and Europe but my information system couldn't
actually infer any additional P7 statement because it doesn't know where the
declarative place of the spatial projection is?
Best,
Wolfgang
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Honorary Head of the
Center for Cultural Informatics
Information Systems Laboratory
Institute of Computer Science
Foundation for Research and Technology - Hellas (FORTH)
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GR70013 Heraklion,Crete,Greece
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