FW: Annotations in 1.0-DL and 1.1-DL [RE: ACTION-102: The situation of deprecation in OWL-1.0-DL and OWL-1.0-Full]

This is conversation between Alan and me about the semantics of annotations
in 1.0-DL. 

Cheers,
Michael


-----Original Message-----
From: Michael Schneider 
Sent: Thursday, March 20, 2008 12:09 PM
To: 'Alan Ruttenberg'
Subject: Annotations in 1.0-DL and 1.1-DL [RE: ACTION-102: The situation of
deprecation in OWL-1.0-DL and OWL-1.0-Full]

Hi Alan!

>-----Original Message-----
>From: Alan Ruttenberg [mailto:alanruttenberg@gmail.com] 
>Sent: Thursday, March 20, 2008 5:14 AM
>To: Michael Schneider
>Subject: Re: ACTION-102: The situation of deprecation in 
>OWL-1.0-DL and OWL-1.0-Full
>
>[not cc]
>
>On Mar 19, 2008, at 9:41 AM, Michael Schneider wrote:
>
>	(So this is very weak semantics. However, it actually 
>*is* semantics. Annotation properties are *not* semantic-free 
>in OWL-1.0-DL!).
>
>
>Yes,
>
>AnnotationProperty(a)
>Individual(i1 annotation(a "be"))
>Individual(i2)
>SameIndividuals(i1,i2)
>
>entails
>
>Individual(i2 annotation(a "be"))

I must confess that I have technical difficulties to either confirm or
disprove this claim.

First, the 1.0-DL semantics [1] for 'SameIndividual' in sec. 3.3 of [1] is:

   Directive                 | Conditions on interpretations
   --------------------------+------------------------------
   SameIndividual(i1 . in)   | S(ij) = S(ik) for 1 <= j < k <= n   

No problem here. Now, the table entry for 'Individual(.)' is:

   Directive:
   ----------
     Individual([i] 
 -->   annotation(p1 o1) ... annotation(pk ok)
       type(c1) ... type(cm) 
       pv1 ... pvn
     ) 	
   
   Conditions on interpretations:
   ------------------------------
     EC(Individual([i] 
 -->   annotation(p1 o1) ... annotation(pk ok)
       type(c1) ... type(cm) 
       pv1 ... pvn)
     ) 
     is nonempty

But here I am confused: The function "EC(.)" isn't defined for individuals
at all. And I also am not sure whether I understand what the intended
semantics is here.

Maybe a bug [FIXME], so better let's have a look at the other entities which
can be annotated, e.g. classes:

   Directive:
   ----------
     Class(c
 -->   annotation(p1 o1) ... annotation(pk ok)
       descr1 ... descrn)

   Conditions on interpretations:
   ------------------------------
 --> S(c) in EC(annotation(p1 o1)) ... S(c) in EC(annotation(pk ok))
     EC(c) subset EC(descr1) ^ ... ^ EC(descrn)

Ok, that's clearer now. We see that the entity, which is denoted by class
name 'c', is an instance of "EC(annotation(pi oi))". And the semantics for
the latter expression is defined in sec. 3.2:

   Abstract Syntax:
   --------------- 	
     annotation(p o) for o a URI reference

   Interpretation (value of EC)
   -----------------------------
     {x in R | <x,S(o)> in ER(p) }
     
('R' denotes the universe/domain, and 'ER(p)' is the property extention of
p, i.e. a subset of RxR.) So for the class 'c' above we have for each i:

   <S(c),S(oi)> in ER(pi)

And if

   SameIndividuals(c c2)    # actually not allowed for classes

would be allowed in OWL-DL, then we would receive

   <S(c2),S(oi)> in ER(pi)

which would mean that all the annotations of class 'c' are also annotations
of class 'c2'. 

So you seem to be right in principle, although there seems to be a bug in
the semantics spec for individuals (but perhaps I overlooked/misunderstood
something?).


>How does OWL 1.1 avoid this?

The 1.1-DL semantics simply seem to ignore annotations which occur in the
functional syntax.

>From sec. 1 of the semantics WD [2]: 

  "OWL 1.1 allows for annotations of ontologies and ontology entities 
  (classes, properties, and individuals) and ontology axioms. 
  Annotations, however, have no semantic meaning in OWL 1.1 
  and are ignored in this document."
  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

And, indeed, if you look through the semantics WD, you won't find any
annotations in the functional syntax. For example, in table 4:

   Axiom                     | Condition
   --------------------------+-----------------------------------------
   SameIndividual(a1 ... an) | a_j^Ii = a_k^Ii for each 1 <= j , k <= n

As in 1.0-DL semantics, there is no mentioning of annotations here. But
unlike the 1.0-DL semantics spec, there is no entry for 'Individual(.)' in
the 1.1-DL semantics WD. 1.1-DL uses such expressions only in declarations
such as:

   Declaration(Individual(x))

And declarations do not have semantics in 1.1-DL. I believe this is meant by
the following excerpt from sec. 1 of [2]:

  "Definitions in OWL 1.1 similarly have no semantics. 
  Constructs only used in annotations and definitions, 
  like ObjectProperty, therefore do not show up in this 
  document."

Just replace 'ObjectProperty' by 'Individual' in this citation.

>-Alan

(Ah, well, this mail got again much too long, sorry for this! :-])

Cheers,
Michael

[1] <http://www.w3.org/TR/owl-semantics/direct.html>
[2] <http://www.w3.org/2007/OWL/wiki/Semantics>

--
Dipl.-Inform. Michael Schneider
FZI Forschungszentrum Informatik Karlsruhe
Abtl. Information Process Engineering (IPE)
Tel  : +49-721-9654-726
Fax  : +49-721-9654-727
Email: Michael.Schneider@fzi.de
Web  : http://www.fzi.de/ipe/eng/mitarbeiter.php?id=555

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