RE: Two bugs in the OWL 2 Direct Semantics and the SS&FSS documents

Hi!

Sorry, I'm a bit late, but trying to catch up on this topic... 

Concerning the 2nd issue: 

>2. A bug in Section 11.2 of the Syntax document
>
>The global restrictions in Section 11.2 of Structural Specification and
>Functional-Style Syntax are designed to ensure that (amongst other
>things) in OWL 2 DL "property assertions connect anonymous individuals
>in a tree-like way"; this is needed in order to ensure decidability.
>Unfortunately, we forgot to disallow anonymous individuals from
>occurring in ObjectHasValue and ObjectOneOf class expressions, which
>means that anonymous individuals *can* be connected in a non-tree-like
>way, and hence fails to ensure decidability.
>
>This problem can be fixed simply by adding the relevant restriction in
>Section 11.2 of Structural Specification and Functional-Style Syntax.

Agreed to disallow anonymous individuals in these constructs.

I can see from the original OWL 1 Abstract Syntax (Sections 2.3.2.2. and
2.3.2.3) that only "individualID"s were allowed to appear in the
corresponding constructs, with "individualID ::= URIreference". So this
alone should be sufficient to justify disallowing anonymous individuals in
these constructs of the OWL 2 Structural Spec., namely by arguing that we
did not intend to create any new ways to use anonymous individuals in
comparison to OWL 1 (at least, this is what I believe to remember was our
intention).

Wrt the "tree-like" and the corresponding decidability argument: I am
curious what you mean by "non-tree-like" here? Something like

    ClassAssertion(ObjectOneOf(_:x) _:x)
    ClassAssertion(ObjectHasValue(ex:p _:x) _:x)

? I am only asking since the "Restrictions on the Usage of Anonymous
Individuals" in Sec. 11.2 of the Structural Spec. does not talk about class
expressions or class assertions at all (at the moment).

Concerning the first issue, all I can say at the moment is that in Sec. 2.3
of the Direct Semantics the sentence that currently defines the ISNAMED
function misses a period at its end. :-)

Cheers,
Michael

--
Dipl.-Inform. Michael Schneider
Research Scientist, Information Process Engineering (IPE)
Tel  : +49-721-9654-726
Fax  : +49-721-9654-727
Email: michael.schneider@fzi.de
WWW  : http://www.fzi.de/michael.schneider

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Received on Monday, 12 April 2010 16:54:20 UTC