[PPL-devel] Re: PPL and parameters

[Sven Verdoolaege]

On Fri, Feb 06, 2004 at 07:48:42PM +0100, Roberto Bagnara wrote:
> I am not sure I understand what you mean.  The current version of the
> PPL is also based on GMP (even though we have a development branch to
> implement support for native integers and other kinds of coefficients, see
> http://www.cs.unipr.it/pipermail/ppl-devel/2004-February/004115.html).

Interesting.  Have you performed any run time comparison ?
A GMP-PolyLib is a lot slower than an integer-Polylib.

> required).  I realize I am probably not answering your question: if
> you can be more specific we will do our best.

Maybe it's just not that much of a problem for PPL.
I notice you perform most operation inline (i.e., _assign),
whereas PolyLib always creates a new polyhedron.

> > A quick glance at the documentation suggests that PPL only
> > supports what Omega would call "set variables".
> > Are there any plans for supporting parameters and/or
> > existential variables ?
> 
> What do you mean by "existential variables"?

The usual.  Existentially quantified variables.
E.g., { x : \exists a : 4 a + 1 <= x <= 4a + 2 }

> I think we will support parameterized polyhedra in the future.
> But this is something that will not happen tomorrow.  

I'll see if I can get a student on it next year.
I'm not holding my breath, though.
Apparently, the word "polytope" scares people off.

skimo