I was wrong: your code works correctly with redundant assertions.
I'd recommend you throw an error if member('inconsistent,_ans).
By the way, why are you defining simp_given as a macro?
-s
On Sat, Jun 2, 2012 at 3:00 PM, Richard Hennessy
<rich.hennessy at verizon.net>wrote:
> Maybe simp_given() could be modified to throw an exception if the facts
> are inconsistent, I'm not sure. I don't think it is broken. I don?t know
> of any bugs at all. The behavior with inconsistent assumptions is (maybe)
> unpredictable but I am not sure if that is a bug. It looks like the
> behavior when the facts are inconsistent is that is uses the facts given up
> until it reaches an inconsistency and then just throws that one away and
> continues with the next assumption in the list. Maybe the help should just
> say that.
>
> kill(all)$
> load(pwlimit)$
> simp_given(e, [fcts]) ::= buildq([e,fcts], block([_ans],
> unwind_protect((_ans:apply(**assume, fcts), expand(e,0,0)),
> apply(forget,_ans))))$
> display2d:false$
> facts();
> -> []
> simp_given(signum(a)+signum(b)**,a<0,a>0,b<0);
> -> -2
> facts();
> -> []
> simp_given(signum(a)+signum(b)**,a<0,a<=b,b<0);
> -> -2
> facts();
> -> []
> simp_given(signum(a)+signum(b)**,a<0,a<b);
> -> signum(b)-1
> facts();
> -> []
> simp_given(signum(a)+2*signum(**b)+4*signum(c),a>0,b<c,a>c,a<**c);
> -> 4*signum(c)+2*signum(b)+1
> facts();
> -> []
> simp_given(signum(a)+2*signum(**b)+4*signum(c),a>0,b>a,c>a,a<**c);
> -> 7
> facts();
> -> []
> simp_given(signum(a)+2*signum(**b)+4*signum(c),a>0,b>a,c<a,a>**c);
> -> 4*signum(c)+3
> facts();
> -> []
> simp_given(signum(a)+2*signum(**b)+4*signum(c),a>0,b>a,c>a);
> -> 7
> simp_given(signum(a)+2*signum(**b)+4*signum(c),a>0,b>a,c>b);
> -> 7
> facts();
> -> []
> simp_given(signum(a)+2*signum(**b)+4*signum(c),a>0,b>a,c>b,c<**a);
> -> 7
> facts();
> -> []
>
> RVH
>
> -----Original Message----- From: Richard Hennessy
> Sent: Friday, June 01, 2012 8:20 PM
> To: Stavros Macrakis ; Barton Willis
>
> Cc: maxima at math.utexas.edu
> Subject: Re: [Maxima] pw.mac
>
> (%i1) simp_given(signum(a),a>0,a<0);
> (out1) 1
> (%i2) facts();
> (out2) [kind(sinh, one_to_one), kind(log, one_to_one), kind(tanh,
> one_to_one), kind(log, increasing)]
>
> Yes, if the assumptions are inconsistent who knows what you?re going to get
> and Maxima has a weak assume system anyway. If the assumptions are
> redundant then I don?t know if it breaks the code. Can you give an
> example.
> Seems okay to me.
>
> Rich
>
> From: Stavros Macrakis
> Sent: Friday, June 01, 2012 7:04 PM
> To: Richard Hennessy ; Barton Willis
> Cc: maxima at math.utexas.edu
> Subject: Re: [Maxima] pw.mac
>
> Richard,
>
>
> I don't know about other issues, but your simp_given won't work right if
> some of the assumptions are redundant. You should use the context
> mechanism, as Barton now is (see mail below).
>
>
> I've also encouraged him to rewrite his simp_assuming and with_assumptions
> functions using contexts.
>
>
> -s
>
>
> ---------- Forwarded message ----------
> From: Barton Willis <willisb at unk.edu>
> Date: Wed, May 16, 2012 at 1:57 PM
> Subject: context based version of abs_integrate--no more
> simp_assuming
> To: "maxima at math.utexas.edu" <maxima at math.utexas.edu>
>
>
> I committed a new version of abs_integrate that uses contexts instead of
> the
> buggy simp_assuming macro. The new code doesn't have a general purpose
> with_assumptions function (or macro) replacement for simp_assuming.
>
> The new version also fixes some other bugs (rtest_abs_integrate bugs 148
> and
> 149).
>
> --bw
>
> ______________________________**_________________
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> Maxima at math.utexas.edu
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>
>
> On Fri, Jun 1, 2012 at 6:13 PM, Richard Hennessy <
> rich.hennessy at verizon.net>
> wrote:
>
> "I don't know what your simp_given function looks like, but
>
> (%i27) ctsp(expr,x,c) := limit(expr, x, c, plus) - limit(expr, x, c,
> minus);
> (%o27) ctsp(expr, x, c) := limit(expr, x, c, plus) - limit(expr, x, c,
> minus)
> (%i28) ctsp(x^2*signum(x-4), x, c);
> 2 2
> (%o28) limit x signum(x - 4) - limit x signum(x - 4)
> x -> c+ x -> c-
>
> However, of course:
>
> (%i29) ctsp(u^2*signum(u-4), x, c);
> (%o29) 0
>
> Could you have a problem with what the dummy variable is or something?"
>
> I forgot to say kill(all). pw.mac was loaded, it changes the answer for
> some reason. If I start with kill(all) then I get what you get. I don't
> know why, maybe because of diff and integrate being modified by pw.mac or
> abs_integrate.mac. Does limit ever call integrate or diff? Either way
> this
> method does not work.
>
> Rich
>
> PS
> simp_given(e, [fcts]) ::= buildq([e,fcts], block([_ans],
> unwind_protect((_ans:apply(**assume, fcts), expand(e,0,0)),
> apply(forget,_ans))));
>
>
>
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>
>
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