Dear both,
I think the discussion was that the "current" status cannot be inferred,
but it is based on a local "closed world" knowledge, and can only be
"true" until the time of the last respective update. So, I think the "no
other move" since time X, or "no other move without back move" since
time X exceeds the scope of logic.
Isn't it?
I fear the "if and only if" statements are wrong anyway. Better you
raise an issue. I fear we have not understood circumstances that can
lead to a custody or loosing etc., including death, heirs etc.
Best,
Martin
On 10/18/2022 7:44 PM, Christian-Emil Smith Ore via Crm-sig wrote:
I tried to say that
P55(x,y) ⇐ (∃z) [ [E9(z) ˄ P25i(x,z) ˄ P26(z,y)]
˄ ¬ (∃w) [E9(w) ˄ P25i(x,w) ˄ P27(w,y)˄
P182(z,w)]]
is not sufficient since the above implication is true if the premise
is false. So if there exist a newer move ( (∃w) [E9(w) ˄ P25i(x,w) ˄
P27(w,y)˄ P182(z,w)]] is true) it is consistent with P55(x,y). The
question is what should the additional axiom be ?
The following is too strong since we do not require knowledge about a
move
P55(x,y) ⇒ (∃z) [ [E9(z) ˄ P25i(x,z) ˄ P26(z,y)]
˄ ¬ (∃w) [E9(w) ˄ P25i(x,w) ˄ P27(w,y)˄
P182(z,w)]]
That was what I thought.
Best,
Christian-Emil
------------------------------------------------------------------------
*From:* Wolfgang Schmidle <[email protected]>
*Sent:* 18 October 2022 17:47
*To:* Christian-Emil Smith Ore
*Cc:* [email protected]
*Subject:* Re: [Crm-sig] Deducing the current custody / ownership /
location
Dear Christian-Emil,
I am not sure I understand your additional axiom. How would it be
expressed in normal language? Are you saying "if the knowledge base
knows that x has current location y and that were was at least one
Move of x, then there must be a Move of x to y after which there is no
more Move of x away from y"?
Best,
Wolfgang
> Am 17.10.2022 um 16:04 schrieb Christian-Emil Smith Ore via Crm-sig
<[email protected]>:
>
> Dear Wolfgang,
> It is clear (at least to me) that the FOLs in the 'current'
properties are too weak. A complicating factor is that the FOL
describes what we explicitly know, that is, the status in the
knowledge system. In a closed world system, all shortcuts will imply
at least one instance of the corresponding long path. This is not the
case in an open world view, I think.
>
> P55(x,y) ⇐ (∃z) [ [E9(z) ˄ P25i(x,z) ˄ P26(z,y)]
> ˄ ¬ (∃w) [E9(w) ˄ P25i(x,w) ˄ P27(w,y)˄
P182(z,w)]]
>
> If the premise in the FOL above is false, then P55(x,y) is trivially
true. This is ok if [E9(z) ˄ P25i(x,z) ˄ P26(z,y)] is false, but it is
not ok if
> (∃z) [ [E9(z) ˄ P25i(x,z) ˄ P26(z,y)] ˄ (∃w) [E9(w) ˄ P25i(x,w) ˄
P27(w,y)˄ P182(z,w)]]
> is true.
>
> We need an additional axiom, something like
> (∃z) [P55(x,y) ˄ [E9(z) ˄ P25i(x,z) ˄ P26(z,y)] ⇒ ¬ (∃w) [E9(w)
˄P25i(x,w) ˄ P27(w,y)˄ P182(z,w)]]]
> ?
> Best,
> Christian-Emil
>
> From: Crm-sig <[email protected]> on behalf of Wolfgang
Schmidle via Crm-sig <[email protected]>
> Sent: 16 October 2022 14:37
> To: [email protected]
> Subject: [Crm-sig] Deducing the current custody / ownership / location
>
> Dear All,
>
> I am trying to understand how one can infer the current custody /
ownership / location of a Physical Thing / Object.
>
> Let's assume that there has been a E10 Transfer of Custody / E8
Acquisition / E9 Move to an Actor or Place y. If there was no later
event at all, it is inferred in the scope notes of P50 has current
keeper / P52 has current owner / P55 has current location that y is,
in fact, the current keeper / owner / location. For example, the scope
note of "P52 has current owner" says: "This property is a shortcut for
the more detailed path from E18 Physical Thing through P24i changed
ownership through, E8 Acquisition, P22 transferred title to to E39
Actor, if and only if this acquisition event is the most recent."
>
> There is a stronger-sounding but actually weaker requirement that
there was no later event that included a "P28 custody surrendered by /
P23 transferred title from / P27 moved from" y. The owner / location
scope notes use the stronger requirement, the keeper scope note uses
the weaker requirement. It would be good to explain in the respective
scope notes the reasoning behind this difference.
>
> The FOL encodes the weaker requirement in all three cases. I assume
the discrepancy between scope notes and FOL is an oversight. (This was
actually my starting point.)
>
> The scope notes not only say "if" but "if and only if". Is there a
way to encode the "only if" part in FOL? This seems to be quite
tricky. For example, if there were three Moves: 1. from somewhere to
A, 2. from A to B, 3. from B back to A, then one can infer that A is
the current location, but only Move 3 (and not Move 1) is actually the
long form of the shortcut "P55 has current location". On the other
hand, it does not follow from Move 1 and 2 that A is not the current
location.
>
> Should we worry about negative statements and incomplete knowledge
in our knowledge base? Or do we assume here that if there has been
such an event, then the knowledge base knows about it? (Or
equivalently, if the knowledge base does not know of any such event,
then there was indeed none?) Of course one can infer e.g. the current
location based on a possibly incomplete list of Moves in a given
knowledge base, but whose opinion would it represent? Can one still
claim that the inferred statement is the opinion of the knowledge base
maintainers?
>
> In particular, what happens if an object disappears or gets
destroyed? One may infer the last keeper / owner / location before the
destruction, but both the scope notes and the FOL will happily argue
that the destroyed object nonetheless has a current owner / keeper /
location. Perhaps the destruction implies an implicit Transfer Of
Custody where the custody has been surrendered, but there is probably
no implicit Acquisition or Move. E64 End of Existence and E6
Destruction offer no concrete help, although E64 says: "It may be used
for temporal reasoning about things … ceasing to exist".
>
> I assume this has already been discussed somewhere, but the
discussion didn't find its way into the scope notes.
>
> Best,
> Wolfgang
>
>
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Information Systems Laboratory
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