W3C home > Mailing lists > Public > www-rdf-logic@w3.org > October 2000

Re: comparing DAML-ONT and OIL (was Re: semantics of daml)

From: Dan Connolly <connolly@w3.org>
Date: Sat, 14 Oct 2000 22:59:58 -0500
Message-ID: <39E92BBE.9013CB8C@w3.org>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
CC: phayes@ai.uwf.edu, www-rdf-logic@w3.org
"Peter F. Patel-Schneider" wrote:
> 
> I did a quick run to put together a VERY brief outline of the
> characteristics of DAML-ONT and OIL-Standard.  This is only the briefest of
> outlines, and many of the points herein could (and should?) be expanded
> considerably for a true comparison of DAML-ONT and OIL-Standard.

I expect it will be more cost-effective to eliminate
the differences (or at least: the inconsistencies)
between the two than to write up a "true comparison".

> Peter Patel-Schneider
> 
>                                 OIL-Standard            DAML 1.2
> 
> Semantics                       denotational            English
>                                 complete, unambiguous   partial, ambiguous

I expect that eventually we can change that DAML entry
here to "provided by OIL", but I haven't finished
studying the OIL denotational semantics.

TODO: see if OIL denotational semantics agree with
my understanding of DAML.

>   Meaning of a collection       always conjunctive      usually conjuctive
>   of statements                                         sometimes disjunctive
>                                                                 (domain from RDF)

I consider RDF to be always conjunctive; the suggestion
(in the RDF spec) that domain is disjunctive is
disputed; one of the RDF schema spec editors
agrees that it's bogus:

[[[
rdfs:domain and rdfs:range were modelled after the similarly named
concepts
in Cycl and have had very well defined meanings right from the
beginning.

(rdfs:domain ?arc ?domain) ^ (?arc ?source ?target) => (rdf:type ?source
?domain)
and
(rdfs:range ?arc ?range) ^ (?arc ?source ?target) => (rdf:type ?target
?range)

and thats it.

Allowing multiple rdfs:domain/rdfs:range with disjunctive semantics is a
bad idea
because it makes the system non-monotonic. Conjunctive semantics are
fine
and
possibly useful.

guha
]]]
--
http://lists.w3.org/Archives/Public/www-rdf-interest/2000Sep/0140.html
Wed, 13 Sep 2000 23:28:09 GMT

> 
> Capabilities
> 
>   Built in Classes              thing, nothing          thing, nothing

I'm not sure what "built in" classes are... in DAML,
Thing and Nothing are just classes, like Property
and Class and Animal and all the rest.

And I'm not sure how Thing and Nothing are supposed to work
(does Thing include literals? numbers? classes?
properties?). I suspect DAML is broken in
some respects here.

TODO: careful review of the "universe of discourse"
in DAML.

>   Primitive Classes             yes                     yes
>   Defined Classes               yes                     maybe, ugly

yeah... gotta think about that one...

TODO: review capabilities of OIL defined classes;
if DAML-ONT doesn't cover them, consider ways
to make up the difference; might end up
punting to DAML-LOGIC rules, TBD
(cf Hendler Fri, 13 Oct 2000 18:06:28 -0400
http://lists.w3.org/Archives/Public/www-rdf-logic/2000Oct/0043.html)

>   Class Hierarchy               yes                     yes, from RDF
>   Property Hierarchy            yes                     yes
> 
>   Equivalence                   yes (defined classes)   maybe

I hope you consider this one "yes" by now.

>   Disjoint, Disjoint Cover      yes                     yes
> 
>   Inverse/Transitive Properties yes                     yes
> 
>   Union/Intersection            yes, class constructor  yes, class definition
>   Complement                    yes, class constructor  yes, class definition
> 
>   Domain Restriction            yes, conjunctive        yes, disjunctive (from RDF)

as I say, I think this is a bug in the RDF spec.

>   Range Restrictions            global and local        global (from RDF) and local
>   Filler Restrictions           local (and global)      local (and global)
>   Cardinality Restrictions      local (and global)      global only

TODO: domain-dependent-cardinality

> 
>   Sets                          yes                     yes
> 
>   Lists                         no                      yes
> 
>   Defaults                      no                      yes
> 
>   Individuals                   yes                     yes

I'm not sure I understand what Individuals are; cf
"universe of discourse" above.

>   Concrete Types (int, ...)     yes                     yes

daml-num is pretty raw.

TODO: study interaction of XML Schema datatypes (int, date, boolean,
...)
with RDF and hence with DAML. see also: universe-of-discourse above.

> Reasoning
> 
>   Specification                 complete                incomplete
> 
>   Completion Possible           no                      no
>   Least Partial Model           no                      no
> 
>   Difficulty                    EXPtime complete (?)    unknown, at least NP hard

How do you conclude that DAML reasoning is at least NP hard
without a specification for it?

Could you point me toward a specification for Least Partial
Model? I learned about models a few months ago, and I
was able to record my understanding in larch[fs]
so I'm fairly confident I understand it, but
I didn't run across the term "Least Partial Model".

[fs] http://www.w3.org/XML/9711theory/FormalSystem
http://www.w3.org/XML/9711theory/FormalSystem.html
http://www.w3.org/XML/9711theory/FormalSystem.lsl
$Id: FormalSystem.lsl,v 1.2 2000/07/27 21:54:19 connolly Exp $

-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Sunday, 15 October 2000 00:00:52 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Monday, 7 December 2009 10:52:37 GMT