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ISSUE:4.1 daml:uniqueProperty PROPOSED RESOLUTION

From: Christopher Welty <welty@us.ibm.com>
Date: Thu, 18 Jul 2002 13:27:25 -0400
To: webont <www-webont-wg@w3.org>
Message-ID: <OF8051C6B8.B5195CB0-ON85256BFA.005F6F71@pok.ibm.com>

ISSUE 3.4: UniqueProp is a bad name

Note: this issue is expanded to include, pending the resolution of issue 
3.4, 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. the range of the 
relation for any given domain is unique.

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 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 does not specify that a relation is "many to one", only that it is
"x to 1" where x may, in fact, be one.


An UnambiguousProp is a relation whose extension is restricted such that 
no object may appear more than once in the range, i.e. the domain of the 
relation for any given range is unique.

If       R is an unambiguousProp
then     R(a,x) ^ R(b,x) -> a=b

Example: BiologicalFatherOf(x,y)

"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 does not specify that a relation is "one to many", only that it is
"1 to x" where x may, in fact, be one. 


To specify a one:one relation, simply make a relation both unambigous and 
unique.


-ChrisW
Received on Thursday, 18 July 2002 13:27:58 GMT

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