Dear All,
The "white elephant example" and the "pinguin" are the two standard
examples discussed very extensively in the literature of the late
1980ies and beginning of 1990ies for illustrating theories of IsA
accepting and propagating exceptions. For some time, IsA with exceptions
was even regarded as a sort of standard. In particular, multiple IsA in
a theory accepting exceptions was shown to be NP hard, i.e. not
computable. When defending multiple inheritance, we were often attacked
that it were not computable. These papers are typically not available on
the Internet, but in printed journals. At that time, all computer
scientists dealing with IsA semantics were very familiar with them.
As such, the paragraph aludes to a more or less vanished opposing
theory. It is however not mixing particulars: "a white elephant" is not
a specific instance.
I see the following solution:
Someone to find in a library a good example of a journal article about
white elephants, citing it, and rephasing the paragraph more clearly
like: "let us assume that the class Elephant has a property : "skin
colour grey"....etc. (I found the example always particularly boring,
because the "white elephant" has only marginally white areas of skin).
The strict inheritance was and is an important objective nomalization
principle for the SIG. Many disputes about alternative arrangements of
IsA hierarchies could be resolved by it.
Further, I think the texts should be clearer that strict inheritance is
also applied to subproperties.
Your point (3) is incomplete. The respctive paragraph appears under:
"Alternatively, a property may be subproperty of the *inverse of*
another property, i.e., reading the property from range to domain. In
that case:
....
"5 the subproperty inherits the definition of all of the properties
declared for the other property without exceptions (strict inheritance),
in addition to having none, one or more properties of its own. The
definitions of inherited properties have to be interpreted in the
inverse sense of direction of the subproperty, i.e., from range to domain."
All proposals for imrovement most welcome!
Cheers,
Martin
On 5/19/2026 5:09 PM, athinak via Crm-sig wrote:
Dear all,
maybe it is not so clear, I don't know; from my understanding, this
is about the position of CIDOC CRM using a logic rule - CIDOC CRM
defines, as you rightly note, strict inheritance in these terms and
the example you mention refers to the fact that to be grey is not part
of the definition of the concept and in that sense we can check the
inheritance rule and the logic and how it can be applied . Cidoc uses
strict inheritance as a normative principle, as a rule to ensure
validity based on the traits found and in combination with the open
world assumption, ensure that data remains valid and logical, even
when information is missing or added later. I think that this example
is used to show how other conclusions on non defining properties
(optional) can produce different classifications based on exceptions
that actually are not part of the definition and are optional
descriptions (the model clarifies that the subclass must inherit the
definition of all its properties, so the example is about a property
that is optional - so, maybe the specific example needs an extra
clarification regarding this exception). Just a thought
BRs,
Athina
On 2026-05-19 15:12, Christian-Emil Smith Ore via Crm-sig wrote:
Hi Øyvind,
4 is not clear, I agree. Could you try to formulate a better
definition or maybe your students could try? (I know this is the
standard trick)
Best,
Christian-Emil
-------------------------
Fra: Crm-sig <[email protected]> på vegne av Øyvind Eide
via Crm-sig <[email protected]>
Sendt: tirsdag 19. mai 2026 12:45
Til: CRM SIG <[email protected]>
Emne: [Crm-sig] Version 7.1.3: Open case on explanation of strict
inheritance
Dear all,
as part of teaching preparation I came across a concept being
described in a way I find confusing in the introduction: strict
inheritance
(1) Page 12, def. subclass: "3 the subclass inherits the definition of
all of the properties declared for its superclass without exceptions
(strict inheritance), in addition to having none, one or more
properties of its own.”
(2) Page 14, def. subproperty: ”the subproperty inherits the
definition of all of the properties declared for its
superproperty without exceptions (strict inheritance), in addition to
having none, one or more properties of its own.”
(3) Page 15, def subproperty (ctd.): ”the subproperty inherits the
definition of all of the properties declared for the other property
without exceptions (strict inheritance), in addition to having none,
one or more properties of its own. The definitions of inherited
properties have to be interpreted in the inverse sense of direction of
the subproperty, i.e., from range to domain.”
(4) Page 15–16, def strict inheritance: ”Strict inheritance means
that there are no exceptions to the inheritance of properties from
superclasses to subclasses. For instance, some systems may declare
that elephants are grey, and regard a white elephant as an exception.
Under strict inheritance it would hold that: if all elephants were
grey, then a white elephant could not be an elephant. Obviously not
all elephants are grey. To be grey is not part of the intension of the
concept elephant but an optional property. The CIDOC CRM applies
strict inheritance as a normalization principle.”
I find the example in (4) confusing due to the mix between
classes/properties and particulars.
All the best,
Øyvind
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--
------------------------------------
Dr. Martin Doerr
Honorary Head of the
Center for Cultural Informatics
Information Systems Laboratory
Institute of Computer Science
Foundation for Research and Technology - Hellas (FORTH)
N.Plastira 100, Vassilika Vouton,
GR70013 Heraklion,Crete,Greece
Email:[email protected]
Web-site:http://www.ics.forth.gr/isl
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