[OWL compatibility] #, ## in OWL compatibility

In RIF-RDF combinations, there is a one-to-one correspondence between
rdf:type statements and # statements, and ## statements imply
rdfs:subClassOf statements, so:

a#b  iff a[rdf:type -> b]   and
a##b implies a[rdf:subClassOf -> b]


These correspondences also hold in RIF-OWL Full combinations, since
their semantics simply extends the semantics of RIF-RDF combinations.

Now, since the semantics of RIF-OWL DL combinations is completely
different, these correspondences do not automatically carry over.  In
fact, in such combinations there is no relationship between # and ##
statements in RIF, on the one hand, and typing and subclass statements
in OWL DL, on the other.  A minimalistic approach was taken in the
specification of the semantics of RIF-OWL DL combinations:
-OWL class membership statements A(?x) correspond to RIF statements
?x[rdf:type -> A]
-property value statements R(?x,?y) correspond to RIF statements ?x[R -> ?y]

There are no further correspondences between statements in OWL DL and in
RIF.  However, some users may expect to be able to use # and ##
statements to access OWL class membership; the document currently does
not explain that this is not possible.
We could do one of three things:
1- leave things as they are, assuming that # and ## are not of interest
to users of RIF-OWL DL combinations
2- explain the use of # and ## in the document (this would certainly not
be a substantive change, so we should not run into procedural problems)
3- define the semantics of # and ## in RIF-OWL DL combinations in a
similar fashion as in RIF-RDF combinations: a one-to-one correspondence
between # and OWL class membership statements and implication between ##
and OWL subclassing.  Technically, this is not a problem.  In principle,
it would be a substantive change, but we might be able to argue that it
was a bug in the specification.

I am fine with any of the options.  Clearly, option 1 would be least
work for me, followed by option 3.
Opinions?

Best, Jos
-- 
Jos de Bruijn            debruijn@inf.unibz.it
+390471016224         http://www.debruijn.net/