[PPL-devel] PPL and simplification of polyhedra

[Roberto Bagnara]

Albert Cohen wrote:
>> Sorry, but I am not following.  When you obtain a minimized constraint
>> or generator system for a polyhedron from the PPL, you don't get
>> any redundancy.  In particular, you do not get constraints that
>> are subsumed by others.  Can you specify precisely the operation
>> that you would like the PPL to provide?
>> Cheers,
> 
> The concept is called "gist" in Omega, and simplification under a
> context in PolyLib. You'd like to run the simplification with the
> assumption that some constraints are already enforced, and only retain
> the additional constraints (minimized) to define a given sub-polyhedron.

Hi Albert,

we need to have a more precise specification of the required operation.
In particular, for the simplification of  { A <= 0 } under the context
{ A >= 0 }, what do you consider simpler?

Possibility 1:  { A <= 0 }
Possibility 2:  { A = 0 }.

Thanks,

    Roberto

-- 
Prof. Roberto Bagnara
Computer Science Group
Department of Mathematics, University of Parma, Italy
http://www.cs.unipr.it/~bagnara/
mailto:bagnara at cs.unipr.it