Re: issues with BLD0921 (part 1 of n)

kifer@cs.sunysb.edu (Michael Kifer) writes:
> 
> > Jeez, I'm sure glad I didn't have Michael for a professor.
> 
> This is a misunderstanding.
> 
> Sandro said that the signature vs name stuff is hard to follow and I am
> eager to make improvements. But I cannot understand what exactly does he
> find to be hard to follow there---hence my question quoted below.
> 
> I was not looking for an explanation of the difference (from you or from
> Sandro). Instead I asked for more concrete info from Sandro to help
> me understand what is wrong with the current text so that it could be
> improved.

It turned out to much easier for me answer your question once I had
Chris' explanation.   What was hard for me was that the terminology kept
conflicting with my intuition about what the terminology meant.

      -- Sandro

> 
> 	--michael  
> 
> 
> > The differences are pretty simple, though:
> > 
> > A signature has a name and a set of expressions.
> > A signature name is just a symbol used to reference the set of expressions.
> > A signature expression is the standard sort of thing you might think of as a 
> > signature, like "(i) => bool", which should be a signature expression for unary 
> > predicates (unary predicates take one argument that is a symbol, and have a 
> > boolean "value") .  So, again, a signature is just a set of valid signature 
> > expressions with a name.
> > 
> > The idea of signatures being sets of signature expressions is because we want 
> > the  basic framework to have the flexibility to define polymorphism, so that you 
> > can express the fact that some constants have different signatures in different 
> > syntactic contexts.
> > 
> > -Chris
> > 
> > 
> > 
> > Michael Kifer wrote:
> > >>   One of the parts that's really hard for me is the distinction between
> > >>   signature names, signatures, and signature expressions.  I can't really
> > >>   keep them straight.
> > > 
> > > Maybe you can explain what you find to be the problem in more detail?
> > > 
> > > I do not quite understand why is it hard to see the difference between a
> > > set and a name given to that set. You do not find it hard to understand the
> > > distinction between the term 'integer' and the set {0, 1, -1, 2, -2, ...}.
> > > So what is so hard about the difference between, say, the symbol 'foobar'
> > > and a set like {i*i->i, i*i*i->bool}, which it might be denoting?
> > > 
> > > 
> > > 	--michael  
> > > 
> > > 
> > > 
> > 
> > -- 
> > Dr. Christopher A. Welty                    IBM Watson Research Center
> > +1.914.784.7055                             19 Skyline Dr.
> > cawelty@gmail.com                           Hawthorne, NY 10532
> > http://www.research.ibm.com/people/w/welty
> > 
> > 
> 
>

Received on Tuesday, 25 September 2007 19:53:09 UTC