Re: Action 299 - removing sorts

> 
> > http://www.w3.org/2005/rules/wg/track/actions/299 has been completed.  Part
> > of the title of this action says: "handle datatypes as in RDF."  This was
> > *not* what was resolved at the F2F and was put in there by mistake (I
> > hope).  Certainly, I would not have agreed to such an action, since I do
> > not know what this might mean in logic.
> 
> As I recall, by that point of the meeting we were in something of a
> hurry, and people were talking over each other, so I guess I can
> understand how you missed this.  In general, there should be a pause and
> people should double check on IRC to make sure their action is recorded
> in a way they are comfortable with.  It sounds like there was a process
> error in not making sure we did that.
> 
> There was not a clerical error in drafting that action, however -- I
> proposed that wording to match my understanding of group consensus.
> 
> Specifically, I heard people saying we still needed some kind of "sort"
> thing for data values, and general murmurs that what RDF has is fine.
> 
> As I understand it, RDF Semantics just formalizes the notion in XML
> Schema that a string like "3" or "2001-01-01" is a lexical
> representation of some individual in a "value space" (the number three,
> or the day Jan 1, 2001), and that a datatype URI identifies a mapping
> from these lexical representations to values.


I am not sure what does it have to do with RDF, but it all you meant "data
types" then yes, it is there.


> The actual spec is:
>       http://www.w3.org/TR/rdf-mt/#dtype_interp
> 
> > Other than that, the main changes are in 
> > http://www.w3.org/2005/rules/wg/wiki/Core/Positive_Conditions
> > http://www.w3.org/2005/rules/wg/wiki/Core/Slotted_Conditions (to a much
> > lesser extent).
> > 
> > Although sorts have been removed, signatures remain. I do not know how
> > to ensure extensibility without signatures. When you read it, you might
> > notice the term "signature name". This has nothing to do with "sort names".
> > Just so that you'd know :-)
> 
> I can't picture what you mean here.   Can you give me an example of how
> signatures help with extensibility?


I should ask you a counter-question: can you specify a series of dialects
(let's say, just two) such that the bottom will be the horn core, as we
agreed, and at the top will be something like HiLog or even common logic?
Do not use signatures, but start with the FOL sharp distinction between the
different kinds of symbols.

Then outline a general way of converting from BNF to XML and then prove that
for every spec S in the horn core FH(S) = FC(S), where FH is the function
that converts the horn core to XML and FC is the same function for the
Common Logic/HiLog dialect.

After thinking about this same problem for a few weeks after the F2F I came
to the conclusion that we need to keep signatures. In fact, signatures
was the original proposal for extensibility. Sorts came in only after
people started talking about data types. We still have sorts * 0.5, by the way,
without calling them such. We just call them XML data types. We just do not
have variables over these sorts (so it is just 1/2 of that concept).


	--michael

Received on Monday, 16 July 2007 18:57:17 UTC