Re: issues with BLD0921 (part 1 of n)

> 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.


	--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 19:23:27 UTC