assume:problems with fractions or multiples of %pi and %e

I think I have found a solution for the problem that the extra facts are
visible to the user.

We write the additional facts from learn-numer and learn-abs in a new
context which I have called '$learndata. We can activate this context.
All facts are present, but not seen by the user with the command
facts();.

This is an example how it works:

(%i2) assume(x<%pi/2);
(%o2) [%pi/2 > x]

The user only sees the fact from the assume statement:

(%i3) facts();
(%o3) [%pi/2 > x]

But the following works now too, because Maxima has put an additional
fact into the database:

(%i4) is(x<%pi);
(%o4) true

These are the contexts. The facts from learn-numer are put into the
context learndata:

(%i5) contexts;
(%o5) [learndata,initial,global]
(%i6) activecontexts;
(%o6) [learndata]

When we use kill(all) the additional facts in learndata will vanish too:

(%i7) kill(all);
(%o0) done
(%i1) contexts;
(%o1) [initial,global]
(%i2) activecontexts;
(%o2) []

Maxima no longer knows that x < %pi:

(%i3) is(x<%pi);
(%o3) unknown

It is possible to have a look at the additional facts. We have to change
the context:

(%i4) assume(x<%pi/2);
(%o4) [%pi/2 > x]
(%i5) context:learndata;
(%o5) learndata
(%i6) facts();
(%o6) [1.570796326794897 > x]

The command forget will work as expected. A fact is removed from both
contexts:

(%i1) assume(x<%pi/2);
(%o1) [%pi/2 > x]
(%i2) forget(x<%pi/2);
(%o2) [%pi/2 > x]
(%i3) facts();
(%o3) []
(%i4) context:learndata;
(%o4) learndata
(%i5) facts();
(%o5) []


First I had to correct a small bug in the routine killcontext. When a
context is killed it is not removed from the list of active contexts.
This causes problems.

This is the code which collects the additional information in the
context learndata:

(when (not (alike (cdr pat) (cdr patnew)))
  (let ((oldcontext $context))

    ;; Switch to the context '$learndata
    ;; If '$learndata does not exist, it is created.
    (asscontext nil '$learndata)

    ;; Put the numerically evaluated fact into the database
    (learn patnew flag)

    ;; Switch back to the context on entry
    (asscontext nil oldcontext)

    ;; Make sure that the context '$learndata is active
    ($activate '$learndata)))

There is one open problem. One example of the testsuite in rtestint.mac
fails. I have to understand why this happens.

Dieter Kaiser