- From: Christopher Welty <welty@us.ibm.com>
- Date: Thu, 18 Jul 2002 14:18:29 -0400
- To: webont <www-webont-wg@w3.org>

[Ignore the previous post from me with the same subject, I pasted the wrong version of this document -CW] ISSUE 4.1: UniqueProp is a bad name Note: this issue is expanded to include, pending the resolution of issue 3.4, the name of daml:UnambiguousProp. Proposed Resolution: Change the name of DAML:UniqueProperty to OWL:FunctionalProperty Change the name of DAML:UnambiguousProperty to OWL:InverseFunctionalProperty Discussion/Explanation: A UniqueProp is a relation whose extension is restricted such that no object may appear more than once in the domain, i.e. for any given element of the domain there is only one value for the range. If R is a UniqueProp then R(a,x) ^ R(a,y) -> x=y Example: Birthdate(x,date) "Any entity with a birthday has only one." Notes: -This is equivalent to expressing a global MaxCardinality restriction (of one) on the relation. -The inverse of a uniqueProperty is an unambiguousProperty. -Birthdate(a,x) and Birthdate(b,x) does not imply anything beyond what the clauses alone imply, other than that a and b share a birthday. -This is more general than but not equivalent to the notion of "many to one", all "many to one" relations are uniqueProperties, but not all uniqueProperties are "many to one", since "one to one" relations are uniqueProperties. An UnambiguousProp is a relation whose extension is restricted such that no object may appear more than once in the range, i.e. for any given element of the range, there is only one value for the domain. If R is an unambiguousProp then R(a,x) ^ R(b,x) -> a=b Example: BiologicalFatherOf(Father,Child) "Every biological father of an entity is the only biological father of that entity" Notes: -This is equivalent to saying that the inverse of a relation is a daml:uniqueProperty. -BiologicalFatherOf(x,a) and BiologicalFatherOf(x,b) does not imply anything beyond what the clauses alone imply, other than that a and b share a father. -This is more general than but not equivalent to the notion of "one to many", all "one to many" relations are unambiguousProperties, but not all unambiguousProperties are "many to one", since "one to one" relations are unambiguousProperties. To specify a one:one relation, simply make a relation both unambigous and unique.

Received on Thursday, 18 July 2002 14:19:02 UTC