The factor function is a little bit silly.

On 2008/4/8, Richard Fateman <fateman at cs.berkeley.edu> wrote:
>
>
>  > -----Original Message-----
>  > From: maxima-bounces at math.utexas.edu
>  > [mailto:maxima-bounces at math.utexas.edu] On Behalf Of J.C. Pizarro
>  > Sent: Monday, April 07, 2008 4:45 AM
>  > To: maxima at math.utexas.edu
>  > Subject: The factor function is a little bit silly.
>  >
>  > I've 2 issues here:
>  >
>  > FIRST: Halting problem in TM
>  > ------
>  > The below symbolic example doesn't terminate after many minutes in
>  > maxima-5.14.0 although the human solution is f(x)-g(x)-h(x):
>  >
>  > factor(expand((f(x)-g(x)-h(x))^500));
>  >
>  > To fix this problem in the future: better artificial
>  > sustitution in the
>  > solving of factor or intelligent lazy computation as
>  > factor(expand(Alpha)) => Alpha.
>
>
> There are many interesting issues that could be characterized as making
>  Maxima more intelligent.
>  This does not look like one. It might be intelligent to say "this is taking
>  a long time. do you want
>  to continue?"
>
>  For a starter, as Alex pointed out,
>   factor(expand(Alpha))  is not generally exactly the same as Alpha.
>
>  Secondly, if you write f(g(alpha)),  that command means apply g to alpha,
>  then apply f to the result.
>
>  If f and g are not programs, or if they are "quoted",  you could define
>  simplifications so that
>  f.g  is the identity ...  that is,   f(g(x)) = x.
>
>  But factor and expand are programs.
>
>  >
>  > SECOND: Non-deterministic Memoization
>  > -------
>  >.....
>
> > I think that the maxima system uses memoization that remember
>  > some internal
>  > answers of previous computations but it's non-deterministic.
>
>
> No, there is nothing non-deterministic about Maxima, even its random
>  function.

I'm sorry, i did answer my mistake to Alexey Beshenov and to Maxima, but
Maxima didn't publish my posted messages because the mines were stopped
in the process of moderation of pipermail, yet not published hours ago.

Please, call to the moderators of pipermail to publish my messages.