On Tue, Apr 8, 2008 at 10:24 PM, Gabriel Dos Reis wrote:
>
> | On Tue, Apr 8, 2008 at 8:59 PM, Gabriel Dos Reis wrote:
>  | > Bill Page writes:
>  | >
>  | > | I can not agree. Because something cannot always be computed
>  | > | does not mean that it is therefore ill-defined. This is especially
>  | > | true in mathematics.
>  | >
>  | >  I believe you're putting confusing the issues.  Function equality
>  | >  is well-defined in classic mathematics (set theoretical).  But
>  | >  that definition is almost useless from algorithmic perspective.
>  | >
>  |
>  | I do not think "almost unless" is synonymous with ill-defined even
>  | from an algorithmic perspective.
>
>  So?

So, I was waiting for you to present the reason why earlier you said:
"From computational (there algorithmic) perspective, function equality
is ill-defined." But so far I have been disappointed.

>
>  | In reply to a similar comment by
>  | Waldek in this thread I characterized the current fully computable
>  | syntactic definition of equality for functions as an "approximation"
>  | to the actual equality.
>
>  The problem I have with that `characterization' is that it does not
>  make any sense from principled computations point of view.  If the
>  game is to just hack up something, we know how to do that.  But I
>  cannot marry your `charaterization' with the nearly worship in
>  category theory.
>

You have injected the words "hack" and "worship" here but I do not
think they are appropriate. What reason do you have to believe that I
worship anything in particular? When have I ever proposed a simple
"hack" just to make something work without asking why it works the way
that it does?

>
>  | I think what it means to be approximate can in
>  | principle be rigorously defined.
>
>  I'm awaiting an *actual* rigorously defined one -- not one that
>  `can be in principle'.  Bcause, after all, I have feed the machine
>  with an actual algorithm.
>
>
>  | >  | For example, the assumed equality of functions, i.e. the
>  | >  | concept of a commutative diagram, is essential for category theory.
>  | >
>  | >  `category theory' is a medium, not the message.  By itself it is void
>  | >  of content.
>  | >
>  |
>  | You would have a hard time convincing me of this
>
>  Then we just have to agree to disagree.  I don't believe in worship in
>  category theory.  I do believe category is an extremely sophisticated
>  and powerful tool... when one has actual *matter* to work with.
>

I do not believe in "worship" of category theory either but I do not
understand what you mean by "actual matter". What counts as *matter*
to you?

>  [...]
>
>  | Would you say that classical set theory is similarly "devoid of
>  | content"?
>
>  The problem with `set theory' is not that it is devoid of content.  It
>  is that it has a overweight non-constructive content.  In essence, it
>  concludes that `bubble sort' and `heap sort' are the same function.
>  That is why it is so inadequate from (algorithmic) computational
>  perspectives.
>

I agree.

Regards,
Bill Page.

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