Search All of the Math Forum:

Views expressed in these public forums are not endorsed by Drexel University or The Math Forum.

Replies: 26   Last Post: May 11, 2011 6:43 PM

 Messages: [ Previous | Next ]
 Daryl McCullough Posts: 2,871 Registered: 1/29/05
Posted: May 9, 2011 2:50 PM

Michael Stemper says...
>
>In article <iq3jjd0665@drn.newsguy.com>, stevendaryl3016@yahoo.com (Daryl
>McCullough) writes:

>>I think this might be a case of divergence between
>>intuitionistic logic and constructive logic.
>>Intuitionistic logic can (I think) prove that
>>every function from R to N must be constant.

>
>What? How about |ceil(x)| or floor(|y|) or
>f(x) = 17 if x<0 and 19 if x>0 or literally numberless other examples?

You can't prove that those define functions, intuitionistically.
For example, if you define a function f(x) = 17 if x < 0, and
f(x) = 19 if x >= 0, for you to be able to say that these two
clauses together define a function, you would need to be able
to prove:

forall reals x, x < 0 or x >= 0

which is not provable, intuitionistically.

--
Daryl McCullough
Ithaca, NY

Date Subject Author
5/7/11 Daryl McCullough
5/7/11 W. Dale Hall
5/7/11 Jack Markan
5/7/11 Daryl McCullough
5/7/11 W. Dale Hall
5/8/11 tommyrjensen@gmail.com
5/8/11 Jack Markan
5/8/11 W. Dale Hall
5/9/11 Jack Markan
5/8/11 Daryl McCullough
5/9/11 Daryl McCullough
5/9/11 Jack Markan
5/7/11 David Yen
5/7/11 David Yen
5/8/11 Jack Markan
5/9/11 Bill Taylor
5/9/11 Daryl McCullough
5/10/11 Daryl McCullough
5/9/11 Michael Stemper
5/9/11 Daryl McCullough
5/11/11 Michael Stemper
5/11/11 Daryl McCullough
5/11/11 hagman
5/11/11 Daryl McCullough
5/11/11 Daryl McCullough
5/9/11 David Yen
5/9/11 David Yen