W3C home > Mailing lists > Public > www-webont-wg@w3.org > January 2002

Re: CHAIR-NOTE: Defaults and etc.

From: Dan Connolly <connolly@w3.org>
Date: 24 Jan 2002 22:17:04 -0600
To: Jim Hendler <hendler@cs.umd.edu>
Cc: webont <www-webont-wg@w3.org>
Message-Id: <1011932224.5188.106.camel@dirk>
On Thu, 2002-01-24 at 21:06, Jim Hendler wrote:
> *** To summarize - our mission is to reach consensus on the MINIMUM 
> langauge we feel comfortable "forcing" everyone to use.

on that much I agree, but your example makes me nervous...

> for example:
> :mammal a owl:class;
>     :birthmethod
>        [def:DefaultValue :LiveBear].
> :platypus a :mammal;
>    :birthmethod :EggLaying.
> :cow a :mammal;
>   That is what I do at the LANGUAGE level.
> Now what does that mean?
> This means any user who reads this is entitled to conclude all and 
> only those facts above and entailed by them.  This (according to D+O 
> semantics) means
> it would be legitimate to conclude
>   :platypus :birthmethod :EggLaying.

er... that much is stated in the input, yes, but...

>   :platypus :birthmethod [def:DefaultValue :LiveBear].

now where do you get this?

>   :cow :birthmethod [def:DefaultValue :LiveBear].

and this? where does it come from?

> and if you want to claim to be an OWL reasoner, you should be able to 
> conclude those things.
> However, I being a smart fellow who wants to make more money than the 
> people who don't have defaults, add some code to MY OWL processor 

your OWL processor? er... maybe your processor, but if it
makes more conclusions than the OWL spec licenses, it's
not an OWL processor any more. i.e. its conclusions can't
be backed by the OWL spec.

You can offer any sort of heuristic service you want that
returns any sort of interesting (or otherwise) conclusions
you want... but if you call it a W3C-OWL processor, I'll probably
send the W3C-trademark/QA cronies after you.

> 1) I am free to add to the langyage and did so with defaults.

no, your extension isn't consistent with the rest of the
language, the way I see it.

> 2) DefaultValue was NOT a requirement of the language
> 3) Those who don't like default reasoning are happy,

Not when folks use your service for a while, then come
to my service, which follows the spec, and they
don't get their default conclusions any more.

> they are not 
> forced to do messy non-logical things.   I have a mechanism that 
> works just fine for my applications, and I can even team up w/Guus 
> and others to get more people to agree to a "standard" way to do this 
> -- so consensus is maintained
> 4) All of us are free to continue research into the best way to do 
> defaults on the web, and if something that is more powerful and 
> everyone likes can be arranged, then we are able to come back to W3C 
> when we do WebOnt 2.0 and add it at that point.
> Further, if a sizable minority of us like a particular solution we 
> can put it on a FAQ page or the like (i.e. "Why doesn't OWL have 
> defaults?"  -- Consensus could not be reached on how best to provide 
> defaults in a manner consistent with the OWL semantics.  However, we 
> suggest that def:DefaultValue be used as follows ... ")
> *** To summarize - our mission is to reach consensus on the MINIMUM 
> langauge we feel comfortable "forcing" everyone to use.  If some 
> solution requires more study, we kludge it and go on.   In short, if 
> you are fighting for a langauge feature to be a requirement, you 
> should not think of it as one YOU cannot live without, you should 
> think of it as one which NO ONE can live without -- it is a different 
> mindset, but important.
>   So, given this - I think we should be very careful with respect to 
> what we decide to do with regard to
>   1) Layering
>   2) Defaults
>   3) Procedural Attachments
> and a number of other things we think are desirable, but don't 
> necessarily have consensus on.  If we cannot reach consensus 
> reasonably soon, my decision will be forced to be that we go with 
> what DAML+OIL does (mandated by our charter) and move on.

W3C process doesn't work that way. The chair can't decide
the design.

The chair could tell The Director that the WG isn't likely
to reach consensus on a design that meets the charter
in the scheduled timeframe...
i.e. advise The Director to close the WG.

But he can't say "this is the spec, even though folks in the WG
don't like it."

>  If that 
> means we are semantically "bad" - so be it, our successors will 
> research this issue and fix it!
> Remember your goal is CONSENSUS, not winning every battle.
>   -JH
> p.s. Yes, I realize that if taken to extreme it means we don't need 
> to do anything and leave the world as it is -- obviously, we have to 
> make some decisions, which is what makes this such fun!

Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Thursday, 24 January 2002 23:17:00 UTC

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