[RuleML-all] RE: RE: [Jdrew-all] Questions regarding RuleML status

[Boley, Harold]

Hi Bart and All,

Thanks for pointing at nested modalities and at modal operators with
a single (propositional) argument. Let me decouple both concerns.

This variation on your nested example shows nested multiple arguments,
namely one for 'Mary' and one for the 'oblige' proposition:

<Atom>
  <Rel modal="yes">suspect</Rel>
  <Ind>Mary</Ind>
  <Atom>
    <Rel modal="yes">oblige</Rel>
    <Ind>John</Ind>
    <Ind>Mary</Ind>
    <Atom>
      <Rel in="no">do</Rel>
      <Ind>something</Ind>
     </Atom>
  </Atom>
</Atom>

I think a future RuleML version's content model for

Atom's having modal Rel's could allow (nested inside) both
  Atom's having uninterpreted Rel's
    and
  Atom's (again) having modal Rel's.

The XML Schema for such attribute-value-dependent content is another
matter.

Perhaps the attributes 'in' (yes, no) and 'modal' (yes, no) could
be merged into a single attribute.

Once we use such nestings for multiple arguments, we can also permit
them for a single (propositional) argument, getting your example:

<Atom>
  <Rel modal="yes">possible</Rel>
  <Atom>
     <Rel modal="yes">oblige</Rel>
     <Ind>John</Ind>
     <Ind>Mary</Ind>
     <Atom>
        <Rel in="no">do</Rel>
        <Ind>something</Ind>
      </Atom>
  </Atom>
</Atom>

My example uses another natural-language inspired modal operator,
'suspect', to show the potential proliferation of modal operators,
which calls for some generic markup, <Rel modal="yes">suspect</Rel>,
rather than non-generic markup, <suspect>.

Your example uses one of the two basic modal operator, 'possible'.
For it and its complement, special tags, <Possible> and <Necessary>,
could be introduced, but this would still entail the risk of a
proliferation of too many tags for various communities' standard
modal operator, including, say, the temporal ones.

Best,
Harold


-----Original Message-----
From: Bart Orriens [mailto:B.Orriens at uvt.nl] 
Sent: April 6, 2006 4:04 AM
To: Boley, Harold
Cc: ruleml-all at ruleml.org
Subject: Re: RE: [Jdrew-all] Questions regarding RuleML status


Hello all,

>Thanks for your persistence!
Also, please accept my apologies here if/when I'm slow >at times.

don't thank me for my persistence yet, might become irritating at some
point :-)

concerning the suggestion Harold made for representing modals, being:

<Atom>
  <Rel modal="yes">oblige</Rel>
  <Ind>John</Ind>
  <Ind>Mary</Ind>
  <Atom>
    <Rel in="no">do</Rel>
    <Ind>something</Ind>
  </Atom>
</Atom>

I have no direct problem with this, except for the following: what to do
if we wish to combine modalities, for example to express that it is
necessary that something will always be the case (combining a modal and
temporal logic modality); or to specify something like 'it is possible
that something is an obligation'?

The above implies the need for some form of nesting where modal
statements can contain other modal statements. It is unclear to me how
we could do this in the above like notation. The only way I see is to
take the above and do something like

<Atom>
  <Rel modal="yes">possible</Rel>
  <Atom>
     <Rel modal="yes">oblige</Rel>
     <Ind>John</Ind>
     <Ind>Mary</Ind>
     <Atom>
        <Rel in="no">do</Rel>
        <Ind>something</Ind>
      </Atom>
  </Atom>
</Atom>

This is most likely not correct RuleML syntax, but hopefully you get the
idea I'm suggesting. Better alternatives are much appreciated of course.

As a side note, when I'm talking about modality I mean the modality of
an atom as a whole. For example, I would like to say something like
'Task A is necessary', in RuleML:

<Atom>
  <Rel modal="yes">necessary</Rel>
  <Atom>
    <oid>
     <Ind>myTask</Ind>
    </oid>
    <Ind>task</Ind>
  </Atom>
</Atom>

Hence why I first suggested using a notation like 

<Necessary>
  <Atom>...</Atom>
</Necessary>

Thoughts, suggestions, remarks always welcome of course.

Cheers,
Bart
=======================================
Drs. Bart Orriens          
B704, Tilburg University 	
PO Box 90153, 5000 LE Tilburg, 	 
The Netherlands
Phone : +31 13 4662779 
Fax   : +31 13 4663069                 
Email : b.orriens at uvt.nl
Web   : http://infolab.uvt.nl/~borriens   
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