On Thu, Feb 19, 2015 at 02:43:51PM -0700, Ondřej Čertík wrote:
> On Thu, Feb 19, 2015 at 5:35 AM, Petr Baudis <[email protected]> wrote:
> > On Wed, Feb 18, 2015 at 11:01:54AM -0600, Aaron Meurer wrote:
> >> On Tue, Feb 17, 2015 at 10:41 PM, Petr Baudis <[email protected]> wrote:
> >> > So one curious observation I have is that even if sym.solve() is given
> >> > multiple equations and only a single variable, it does yield a solution
> >> > in this case. I'm still confused about what the exact API contract of
> >> > sym.solve() is. Working "sometimes" leaves me unsure about what I can
> >> > or cannot rely on...
> >>
> >> Sadly, there is none. Part of this is due to algorithmic limitations
> >> (solve() is basically a bunch of heuristics, there are few guarantees
> >> that it will find a solution if it exists). But a lot of it is just
> >> poor design. We are trying to make the design better with the new
> >> solveset module.
> >
> > Thanks! Knowing this is quite valuable for me.
> >
> >> >> Right now I'm inclined to conclude that what I want to do *is* rather
> >> >> hard and I'd have to come up with some new algorithms to deal with this.
> >> >> (Or likely take a look at some other CASes first if any handle this case
> >> >> for me already.)
> >>
> >> If you find some other CAS that can do this better, please let us know
> >> and post here your solution. As Aaron said, we would like to improve
> >> our solver module.
> >
> > I will for sure - my plan is to take a hard look at Maple and a brief
> > look at Mathematica. If I won't be successful, I might come back to
> > SymPy and try to help improve the solveset module (I can't promise
> > I will have the time though, this was supposed to be just a small piece
> > of puzzle in a larger project - http://21robot.org/).
>
> Are you trying to do all of this:
>
> http://21robot.org/research_activities/math/
>
> ?
Actually, I'm working on physics questions (not sure why these aren't
listed on the homepage). The nature of the questions is not always
the same, but SAT questions are reasonable examples of what we are
trying to solve, e.g.:
http://papers.xtremepapers.com/SAT/SAT%20II%20Success%20Physics.pdf.pdf
The pipeline should convert text to logical form (set of predicates
that describe the situation and the question) and currently the logical
form is transformed to Modelica statements and the situation is
simulated. I'm trying to explore an alternate avenue of converting the
predicates to a system of equations and solving them symbolically.
--
Petr Baudis
If you do not work on an important problem, it's unlikely
you'll do important work. -- R. Hamming
http://www.cs.virginia.edu/~robins/YouAndYourResearch.html
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