[Crm-sig] Symmetry of P130 and P139

Martin Scholz martin.scholz at informatik.uni-erlangen.de
Thu Mar 31 20:13:24 EEST 2011


Dear All,

the scope notes of P130 and P139 are as follows:

P130:
This property generalises the notions of "copy of" and "similar to" into a
dynamic, asymmetric relationship, where the domain expresses the derivative, if
such a direction can be established. Otherwise, the relationship is symmetric.
It is a short-cut of P15 was influenced by (influenced) in a creation or
production, if such a reason for the similarity can be verified. Moreover it
expresses similarity in cases that can be stated between two objects only,
without historical knowledge about its reasons.

P139:
This property establishes a relationship of equivalence between two instances of
E41 Appellation independent from any item identified by them. It is a dynamic
asymmetric relationship, where the range expresses the derivative, if such a
direction can be established. Otherwise, the relationship is symmetric. The
relationship is not transitive. The equivalence applies to all cases of use of
an instance of E41 Appellation. Multiple names assigned to an object, which are
not equivalent for all things identified with a specific instance of E41
Appellation, should be modelled as repeated values of P1 is identified by
identifies). P139.1 has type allows the type of derivation, such as
"transliteration from Latin 1 to ASCII” be refined..


Both scope notes state that the properties are dynamic asymmetric, i.e. may be 
both symmetric and asymmetric, depending on the type of relation the property
instances resemble.
This is misleading and calls for clarification, as
a) the term dynamic asymmetric relation is not defined
b) from a mathematical/logical point of view, a relation may not be both
symmetric and asymmetric. (but it may be neither sym. nor asym.!)

Furthermore, P130 defines an inverse property while P139 does not. This is
inconsistent. If both properties are regarded as symmetric, the inverse of P130
should be removed. If both are not symmetric, an inverse should be added to P139.
A solution could be to define P130 and P139 as not symmetric and include inverse 
properties for both. If symmetric properties are needed, new (sub)properties of 
P130 and P139 need to be introduced which are then marked as symmetric and 
without inverses.


Kind regards
Martin Scholz

-- 
Martin Scholz, Dipl-Inf.
Artificial Intelligence Division
Department of Computer Science
University of Erlangen-Nuremberg
Haberstr. 2
91058 Erlangen

martin.scholz at informatik.uni-erlangen.de



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