[SCL] Re: Report on Common Logic

[Tanel Tammet]

Hi,

pat hayes wrote:
>>>> Murray Altheim wrote:
>>>
>>>
>>>>> After that's done, an XML syntax still isn't completely
>>>>> straightforward. Like any language, you need to decide exactly
>>>>> what you're trying to do with it. Just *one* of the questions
>>>>> I brought up early on was "web-enabled" or not? Use of URIs or
>>>>> not? Any extensibility, so it can be the basis of other languages?
>>>>
>>
>> I'm not concerned any more than you with this being "boring". I am
>> concerned with its usability and whether or not it meets a set of
>> requirements. Those two things are of course inextricably tied. I
>> would still prefer a set of specific requirements for this work; I'm
>> guessing this isn't going to happen, so perhaps I can just field
>> questions and see if nobody screams when I answer them as best I can
>> based on what I see on the list, rather than in a requirements document.
> 
> 
> OK, since time is short let me suggest answers to your questions. Anyone 
> else disagree, chime in ASAP.

I have a few comments.

The basic issue is that it would be worrisome if XML
syntax in the SCL spec would give SCL-in-XML
_more expressive power_ than say, SCL in KIF or
"traditional" or N3 syntax or whatever.

In other words, anything having any _meaning_ in
SCL-XML spec should be expressible in other SCL syntaxes
(at least for the purposes of our spec!)

Hence, the nice stuff Murray was thinking about for
the XML syntax should be in our report also for
the ABSTRACT syntax, or not at all.

The way do to this is to reserve some function
and predicate symbols in SCL full, plus have
strings in SCL full.

Then we would have a capability in syntax to
somehow express in semantics that
something like

URL(STRING("http://www.w3c.org"))

is an URL, whatever this means (I see no
other way to give meaning for such things
than to say that there is simply a subset of strings,
which is called URL-s, without saying anything about
how these URL-s etc are used).

>>   Web Enabled:
>>      1. Do we want XCL documents to be able to refer to other XCL
>>         documents over the web? This would be how modules could be used
>>         to construct larger statements/formulae/ontologies/etc.
> 
> 
> If this can be managed easily, yes. I think there is only  a need to do 
> this at the 'top level', ie for one ontology to consist of several XCL 
> documents. One way to do this would be to include a kind of 'importing' 
> mechanism, meaning: include all the SCL axioms from that document in here.
> 
> I think it would be good if XCL could be mixed with other content in an 
> XML document without that affecting the SCL content.

I agree. But this should be ANOTHER layer, not the
SCL layer, which does this.

For example (to go to extremes) we will not make SCL
"http-enabled" and  start describing http issues
in the SCL spec.

Ie, it is http-enabled without any efforts from our
side :-)

>>      3. are there meant to be internal link targets within an XCL 
>> document?
> 
> 
> Not it the first instance, I think.

We could have them nicely, by using annotations:
put a special-syntax string in the annotation and
refer to that.

But, again, this is ANOTHER LAYER, not SCL spec.

Regards,
        Tanel Tammet