Martin Doerr (pc) 7 Feb 2024
(...)
I also encountered that we can solve an old problem elegantly, the "restricted IsA":
Frequently, we specialize a class and its property, meaning that this superproperty may not explicitly be instantiated for the subclass. The FOL is easy: Just write that subclass and superproperty implies subproperty.
Best,
Martin
Christian-Emil Ore (pc) 15 February 2025
[...]
Here you need to be more explicit:
" I also encountered that we can solve an old problem elegantly, the "restricted IsA":
Frequently, we specialize a class and its property, meaning that this superproperty may not explicitly be instantiated for the subclass. The FOL is easy: Just write that subclass and superproperty implies subproperty.
This is an old question: For classes A, B and A' where A' is a subclass of A, P, A -> B, P': A' -> B where P' is a subproperty of P is P identical to P' when P us restricted to P'? It is clear that P'(x,y) implies P(x,y) from the rules for FOL formulations. The question is if P(x,y) and A'(x) implies P'(x,y) or not. My impression is that this issue has been discussion once a while in the last 20 years but no explicit decision has been taken. The cleanest and most common practice in object oriented modelling and programming is that the superproperty is identical to the subproperty when restricted to the domain and range of the subproperty. I suggest we introduce this formally in CRM.
Best,
Christian-Emil
Christian-Emil Ore (pc) 1 March 2024
The discussion was a little diverted to a discussion about strict inheritance. This may be another issue, but I suggest we add under the entry for subproperty in the terminology section (between point 5 and 6 in the list):
the superproperty is identical to the subproperty when restricted to the domain and range of the subproperty
The will require the following adjustment of the FOL exemplified by P32 below.
E7(x) ∧ E55(y) ∧ P2(x,y) ⇒ P32(x,y)
or better (?)
E7(x) ∧ E55(y) ⇒ [P2(x,y) ⇔ P32(x,y)]
Wolfgang, opinions?
[...]
Best,
Christian-Emil
Martin Doerr (pc) 1 March 2024
Dear Christian-Emil,
A) Yes, the issue of restricting superproperties to a subproperty is a different issue.
I will present a series of such statements for harmonizing reification with Named Graphs of factual statements(!).
I agree with the dformulation of the constraint:
E7(x) ∧ E55(y) ⇒ [P2(x,y) ⇔ P32(x,y)],
but not that any type of activity is a general technique.
Obviously, restricting a superproperty implies that the superproperty is not necessary. I further maintain that restricting a superproperty to a subproperty is case-specific semantics.
See also: https://www.sciencedirect.com/science/article/abs/pii/S0306437998000015
[...]
What do you think?
All the best,
Martin
Christian-Emil Ore (pc), 2 March 2024
Dear Martin,
Firstly, "Obviously, restricting a superproperty implies that the superproperty is not necessary" The other way round?
I am happy with the fact that a subproperty is not identical to its superproperty restricted to the domain and range of the subproperty in our model. Participate does not imply perform but the other way round is as it is decribed in CRM.
[...]
Best,
Christian-Emil
Martin Doerr (pc) 4 March 2024
The definition of a property of a subclass as subproperty of a property of a superclass may require to exclude other interpretations of the said superproperty for instances of the subclass. This issue should clarify the way this constraint is expressed in FOL, in the scope note, or even in the superproperty declaration, and what other logical constraints such a declaration may imply.
A possible FOL version may be:
B(x) ⇒ A(x) "subclass of"
pb(x,y) ⇒ B(x)
pa(x,y) ⇒ A(x)
pb(x,y) ⇒ pa(x,y) "subproperty of"
B(x) ∧ pa(x,y) ⇒ pb(x,y) "the restriction of pa for all instances of B"
Christian-Emil Ore (pc) 4 March 2024:
For clarity, may be it is best to include both domain and range?
C-E
Martin Doerr (pc) 4 Mar 2024
Interesting question. Before studying the subject more, I assume that even the same range can be sufficient to justify a restriction, once the meaning of pb/pa is in the scope note, isn't it?
In the 61st joint meeting of the CIDOC CRM and ISO/TC46/SC4/WG9 & 54th FRBR/LRMoo SIG, the group reviewed issue 677 to determine what needs to be done (in terms of scope of the issue, HW assignment, etc.).
CEO thinks that the proposal by MD on how to restrict defining a property of a subclass as subproperty of a property of a superclass through additional FOL constraints, is valid and should be used as such. Following implementng that, the issue can be closed.
However, given that the issue was not properly contextualized, HW was assigned to ETs to locate the email exchanges and provide some more background. Also, to contact MD for a follow-up on the issue.
Heraklion, October 2025