[Maxima] Assume behavior

Karl-Dieter Crisman kcrisman at gmail.com
Mon Sep 28 12:49:09 CDT 2009


Dear Maxima list,

Thanks for taking a newbie question.  I have used Maxima through Sage
a fair amount, but only recently started using it stand-alone as well
(some of you know this already).  I have a question about the use of
assume.

http://maxima.sourceforge.net/docs/manual/en/maxima_11.html says that
the deduction mechanism is "not very strong".

Maxima 5.19.1 http://maxima.sourceforge.net
Using Lisp SBCL 1.0.30
Distributed under the GNU Public License. See the file COPYING.
Dedicated to the memory of William Schelter.
The function bug_report() provides bug reporting information.
(%i1) assume(x>=y,y>=z,z>=x);
(%o1)                      [x >= y, y >= z, z >= x]
(%i2) is(x=z);
(%o2)                                false
(%i3) maybe(x=z);
(%o3)                                false

Maxima 5.19.1 http://maxima.sourceforge.net
Using Lisp SBCL 1.0.30
Distributed under the GNU Public License. See the file COPYING.
Dedicated to the memory of William Schelter.
The function bug_report() provides bug reporting information.
(%i1) assume(x<=1);
(%o1)                              [x <= 1]
(%i2) assume(x>=1);
(%o2)                              [x >= 1]
(%i3) is(x=1);
(%o3)                                false
(%i4) maybe(x=1);
(%o4)                                false

Maxima 5.19.1 http://maxima.sourceforge.net
Using Lisp SBCL 1.0.30
Distributed under the GNU Public License. See the file COPYING.
Dedicated to the memory of William Schelter.
The function bug_report() provides bug reporting information.
(%i1) assume(x>0);
(%o1)                               [x > 0]
(%i2) is(x#1);
(%o2)                                true
(%i3) maybe(x#1);
(%o3)                                true

My question is whether there is more explicit documentation on the
behavior of is() than at
http://maxima.sourceforge.net/docs/manual/en/maxima_5.html#Item_003a-is.
 It mentions that it essentially calls ev(), but the documentation for
that function only say, "pred causes predicates (expressions which
evaluate to true or false) to be evaluated," but doesn't seem to
indicate if that occurs in some other Maxima module or elsewhere.

Thank you for any help; I greatly appreciate it.


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