[PPL-devel] simplifying a constraint system?

[Roberto Bagnara]

Basile STARYNKEVITCH wrote:
> Hello All
> 
> [Sorry for the very naive & basic question]
> 
> I have constructed some constraint system using the C API. I know I'm 
> done constructing it.
> 
> Is there some function to "simplify" it or represent it more efficiently?
> - perhaps onverting it to NNC_Polyhedron and backwards, using 
> ppl_new_NNC_Polyhedron_from_Constraint_System 
> <http://www.cs.unipr.it/ppl/Documentation/user/ppl-user-c-interface-0.10-html/interfaceppl__Polyhedron__tag.html#304dd0846a62cb4a9f79806ea82cee5d> 
> & ppl_Polyhedron_get_minimuzed_constraints 
> <http://www.cs.unipr.it/ppl/Documentation/user/ppl-user-c-interface-0.10-html/interfaceppl__Polyhedron__tag.html#85417db0eb420d402acee4ef0d842efc> 
> ?
> Is there some function to test that it is empty?
> - perhaps  using 
> <http://www.cs.unipr.it/ppl/Documentation/user/ppl-user-c-interface-0.10-html/interfaceppl__Polyhedron__tag.html#50d5c68064e215d3f2cf3ee69896e676>ppl_new_NNC_Polyhedron_from_Constraint_System 
> <http://www.cs.unipr.it/ppl/Documentation/user/ppl-user-c-interface-0.10-html/interfaceppl__Polyhedron__tag.html#304dd0846a62cb4a9f79806ea82cee5d> 
> & ppl_Polyhedron_affine_dimension 
> <http://www.cs.unipr.it/ppl/Documentation/user/ppl-user-c-interface-0.10-html/interfaceppl__Polyhedron__tag.html#50d5c68064e215d3f2cf3ee69896e676> 
> 
> A concrete case occuring to me is the constraint system of two variables 
> n and y with constraints {n = 10, y = 17, -n >= 0} I need to compute 
> that it is empty.
> 
> Is there some function to test that it has integer elements, in the 
> sense that there exist an integer setting of the variables such as the 
> constraint are satisfied?
> - perhaps using grids?
> 
> Sorry for such basic questions!
> 
> Regards.
> 
> PS I'm only using the C API!
> 


-- 
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