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Re: Where are the semantics in the semantic Web?

From: Bijan Parsia <bparsia@isr.umd.edu>
Date: Fri, 25 Nov 2005 15:29:09 -0500
Message-Id: <b03c514744d1452abfac15c294016422@isr.umd.edu>
Cc: public-sws-ig@w3.org
To: Harry Halpin <hhalpin@ibiblio.org>

On Nov 25, 2005, at 2:29 PM, Harry Halpin wrote:

> Quick response and then no more - and I end on what I think people are
> trying to say in a constructive manner...
>
> As for Bijan's confusing denotational/operational semantics,
[snip]

Excuse me, I didn't confuse them (at least in general). I thought 
that's what they were doing based on my memory of other work in this 
area. When I asked if it were operational, I was asking a factual, not 
a conceptual question. It's not entirely obvious from a quick 
skim...er... unless you skim all the way down to 3.2, in which case it 
looks quite operational. (The bottom up evaluations of expressions were 
confusing me.) Oh well.

[snip]
> Operational semantica (from Plotkin) has evaluation and
> execution relations specified by rules directed by syntax, the
> denotational semantics (from Scott) uses rich mathematical models ala
> partial orders, least fixed points

Sigh. Doesn't it depend on the complexity of the language? The main 
point of difference is that operational semantics explicate meaning in 
terms of the operations of an "abstract machine", whereas denotational 
semantics provide an interpretation function (as with "normal" model 
theory). Note that denotational semantics is quite syntax driven 
(valuations for expressions depend on the valuations of their parts), 
so your contrast is a bit confused.

Of course, this doesn't matter since originally we were just looking 
for a "formal semantics". If you wanted a denotational semantics 
(rather than any sort of formal semantics), ask for it. I don't see it 
helps you, though.

I notice that you didn't address the main point, either. Regardless of 
the *style* of semantics given, the expressiveness of the language 
either lets you do certain things or not. The rest of your post make no 
headway in rejoining to that, so I think it's mere bluster. Might be 
more gracious to concede that point rather than hurling insult and a 
whirlwind of irrelevancy.

Cheers,
Bijan.
Received on Friday, 25 November 2005 20:29:15 GMT

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