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ISSUE:4.1 daml:uniqueProperty PROPOSED RESOLUTION

From: Christopher Welty <welty@us.ibm.com>
Date: Thu, 18 Jul 2002 14:18:29 -0400
To: webont <www-webont-wg@w3.org>
Message-ID: <OFFCF5957B.CC85EFC5-ON85256BFA.006360C6@pok.ibm.com>

[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 GMT

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