Wiki-page on EL++ and ISSUE-79

Dear all,

as proposed by Jim, I have set up a Wiki page with details on the EL++
tractable fragment of OWL 1.1 DL. You can find it at

The version of EL++ given there is, in my opinion, the natural version
of EL++ that comes up as a fragment of OWL 1.1 DL. It differs from the
one given in Bernardo's "tractable fragments" document in a number of
(mostly minor) ways. Notably,

- some additional expressive power is added, such as reflexive properties,
   facts, and datatypes

- a nonstructural restriction is adopted to achieve tractability (the
   fragment reported in Bernardo's document doesn't have it, and turns
   out to be at least PSpace-hard).

>From my perspective, this settles ISSUE-79 (raised by myself), which asks
for the appropriate version of EL++ that we should consider within this

As an aside: note that my wiki page is quite long. If EL++ should
become part of the standard, I feel that the document should be even
more detailed. This indicates that standardizing a larger number of
tractable fragments will be quite a bit of work, and produce quite
long documents.


PS: Bernardo, if you want to integrate all or some of this in your
     document, please go ahead.

*      Carsten Lutz, Institut f"ur Theoretische Informatik, TU Dresden       *
*     Office phone:++49 351 46339171     *

Received on Wednesday, 12 December 2007 14:07:55 UTC