I believe Barton has succeeded with it. Take a look at his code.
-s
On Sun, Jun 3, 2012 at 9:02 PM, Richard Hennessy
<rich.hennessy at verizon.net>wrote:
> I played around with the context stuff and got frustrated because I
> could not get it to work. I am not sure why, the error message I got was
> useless, something like ?error in errmsg1? or something similar. So I
> thought, I don?t know if the context mechanism works or not. I once posted
> a question to this list asking if anyone knew if the context system was
> broken. I got no reply. That was probably well over a year ago. I was
> trying this method back then and I was having problems. So I decided to
> bypass that subsystem and came up with simp_given() instead. If anyone can
> get it to work then I would use it. I have doubts, no one replied, makes
> you wonder. I have doubts about the new simp_given() but it will do for
> now. If someone can do better with contexts then kudos to them.
>
> Rich
>
>
> *From:* Stavros Macrakis <macrakis at alum.mit.edu>
> *Sent:* Sunday, June 03, 2012 6:22 PM
> *To:* Richard Hennessy <rich.hennessy at verizon.net>
> *Cc:* Barton Willis <willisb at unk.edu> ; maxima at math.utexas.edu
> *Subject:* Re: [Maxima] pw.mac
>
> Richard,
>
> I don't understand why you're building messy wheels within wheels to work
> around the quirks of assume/forget when the context mechanism was designed
> precisely to solve the problem you have -- simply and straightforwardly
> (and if it doesn't, it's a bug in the context system, not your code).
>
> As for
>
>
> there is no way to fix Maxima if it allows inconsistent facts to be
> present at the same time, which it does.
>
>
> Are you referring to your sequence (assume(c>1), c:-1)? Yes, it is true
> that Maxima does not object to this. Not sure how it could. Checking the
> compatibility of every assignment with the assumption database would make
> assignments prohibitively expensive. Anyway, even leaving aside
> theoretical limits on inference, Maxima's assumption inference engine is
> pretty weak .
>
> -s
>
> On Sun, Jun 3, 2012 at 11:38 AM, Richard Hennessy <
> rich.hennessy at verizon.net> wrote:
>
>> I have come up with a fix to the leaking problem in simp_given() that
>> fixes these two bugs and I don't think it can get any better than this even
>> if you use contexts, but I am not sure of that.
>>
>> (%i19) kill(all);
>> (out0) done
>> (%i1) load(pw);
>> (out1) C:/Maxima-5.27.0/share/maxima/**5.27.0/share/contrib/pw.mac
>> (%i2) assume(c>0);
>> (out2) [c > 0]
>> (%i3) facts();
>> (out3) [kind(sinh, one_to_one), kind(log, one_to_one), kind(tanh,
>> one_to_one), kind(log, increasing), c > 0]
>> (%i4) c:-1;
>> (out4) - 1
>> (%i5) facts();
>> (out5) [kind(sinh, one_to_one), kind(log, one_to_one), kind(tanh,
>> one_to_one), kind(log, increasing), c > 0]
>> (%i6) simp_given(c,c>1);
>> (out6) - 1
>> (%i7) facts();
>> (out7) [kind(sinh, one_to_one), kind(log, one_to_one), kind(tanh,
>> one_to_one), kind(log, increasing), c > 0]
>> (%i8) simp_given(signum(c),c>1);
>> (out8) 1
>> (%i9) facts();
>> (out9) [kind(sinh, one_to_one), kind(log, one_to_one), kind(tanh,
>> one_to_one), kind(log, increasing), c > 0]
>> (%i10) d:c;
>> (out10) - 1
>> (%i11) facts();
>> (out11) [kind(sinh, one_to_one), kind(log, one_to_one), kind(tanh,
>> one_to_one), kind(log, increasing), c > 0]
>> (%i12) simp_given(signum(c),c>d);
>> (out12) 1
>> (%i13) simp_given(signum(c),d>0);
>> (out13) 1
>> (%i14) facts();
>> (out14) [kind(sinh, one_to_one), kind(log, one_to_one), kind(tanh,
>> one_to_one), kind(log, increasing), c > 0]
>> (%i15) simp_given(signum(d),d>0);
>> (out15) - 1
>> (%i16) facts();
>> (out16) [kind(sinh, one_to_one), kind(log, one_to_one), kind(tanh,
>> one_to_one), kind(log, increasing), c > 0]
>> (%i17)
>>
>> This is better but still wrong in some ways but there is no way to fix
>> Maxima if it allows inconsistent facts to be present at the same time,
>> which it does.
>>
>> Rich
>>
>> PS Here is the new improved and better simp_given().
>>
>> simp_given(__e, [__fcts]) ::=
>> buildq
>> (
>> [__e,__fcts],
>> block
>> (
>> [_fct, _otherfacts:facts()],
>> unwind_protect
>> (
>> (
>> apply(assume, __fcts),
>> expand(__e, 0, 0)
>> ),
>> for _fct in facts() do
>> (
>> if not member(_fct, _otherfacts) then
>> apply('forget, ['_fct])
>> )
>> )
>> )
>> );
>>
>> I have updated pw.mac on www.sourceforge.net with this fix. I changed
>> the version number to 6.5.
>>
>>
>>
>> -----Original Message----- From: Richard Hennessy
>> Sent: Saturday, June 02, 2012 7:34 PM
>> To: Barton Willis ; Stavros Macrakis
>>
>> Cc: maxima at math.utexas.edu
>> Subject: Re: [Maxima] pw.mac
>>
>> Oops, your both right. I didn't catch these cases. It is a bug.
>> Contexts
>> should fix that.
>>
>>
>> -----Original Message----- From: Barton Willis
>> Sent: Saturday, June 02, 2012 5:25 PM
>> To: Stavros Macrakis ; Richard Hennessy
>> Cc: maxima at math.utexas.edu
>> Subject: RE: [Maxima] pw.mac
>>
>>
>> A crazy chained assignment:
>>
>> (%i3) (a : b, b : c, c : d, d : e)$
>>
>> No facts:
>>
>> (%i4) facts();
>> (%o4) []
>>
>> Call simp_given on 1 with one fact a < b
>>
>> (%i5) simp_given(1,a<b);
>> (%o5) 1
>>
>> And oops--a fact leaked out:
>>
>> (%i6) facts();
>> (%o6) [d>c]
>>
>> Isn't this a bug?
>>
>>
>>
>> --Barton
>>
>>
>>
>> ______________________________**_________________
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>> Maxima at math.utexas.edu
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>>
>
>