Re: Expressivity of sub property chains

From: Ian Horrocks <horrocks@cs.man.ac.uk>
Date: Sat, 8 Sep 2007 14:46:04 +0100
Message-Id: <93A8B260-3EEC-415E-82AA-E41155EC5876@cs.man.ac.uk>
Cc: <public-owl-dev@w3.org>, <EZolin@cs.man.ac.uk>
To: "Michael Schneider" <schneid@fzi.de>
```
Yes, you get your uncle -- in later versions of our work on complex
role inclusion axioms (on which this aspect of OWL 1.1 is based) we
were able to relax the restrictions that ensure decidability. It has
recently been shown that even further relaxation of these
restrictions is possible [1].

Ian

[1] Yevgeny Kazakov, Ulrike Sattler, Evgeny Zolin. How many legs do I
have? Non-simple roles in number restrictions revisited. In Proc. of
the 14th Int. Conf. on Logic for Programming, Artificial
Intelligence, and Reasoning (LPAR'2007). http://www.cs.man.ac.uk/
~ezolin/pub/zolin_2007_LPAR.pdf

On 8 Sep 2007, at 13:53, Michael Schneider wrote:

>
> Hi, list!
>
> I wonder if it will be possible in OWL-1.1 to express (the one
> direction of)
> the "uncle" relation
>
>     (?x hasParent ?y), (?y hasBrother ?z) -> (?x hasUncle ?z)
>
> or not?
>
> Until now, I always had the restrictions in mind as given by Evgeny
> Zolin's
> DL Complexity Simulator [1]: There, "complex role inclusions" (the
> "R" in
> "SROIQ" aka OWL-1.1), are shown in two variants:
>
>     R - Complex role inclusions:
>         RoS \subseteq R,
>         RoS \subseteq S
>
> So from this it seems that the upper role does always have to be
> one of the
> roles in the chain. And with this restriction, the "uncle" relation
> would be
> out of play.
>
> But the OWL-1.1 draft [2] does not seem to make this restriction:
>
>     SubObjectPropertyOf(
>         SubObjectPropertyChain(R1 ... Rn) S )
>
> AFAICS, there seems to be no requirement that one of the chain
> properties
> R_i have to equal the upper property S.
>
> So, will I get my uncle, or not?
>
> Cheers,
> Michael
>
> [1] http://www.cs.man.ac.uk/~ezolin/dl/
> [2] http://webont.org/owl/1.1/semantics.html#2
>
> --
> 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
>
> FZI Forschungszentrum Informatik an der Universität Karlsruhe
> Haid-und-Neu-Str. 10-14, D-76131 Karlsruhe
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>
```
Received on Saturday, 8 September 2007 13:46:34 UTC

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