[PPL-devel] Complement of a logical Equation

[Enea Zaffanella]

Hello.

The PPL encodes some forms of logical statements as constraints. "a = 5" 
can be encoded as a Constraint object as follows (in the appropriate 
context, assuming you are using the C++ interface):

Variable a(0);
Constraint c(a == 5);

There is no way to compute the complement of an equality constraint, 
because it is not a hyper/half space (it is the union of two open 
half-spaces).

You can compute the two half-spaces separately: the constraint above is 
encoded as "a - 5 == 0".
You can tale the underlying linear expression (a - 5) and use it to 
construct the two open half-spaces
(a - 5 < 0 and a - 5 > 0).

Hope my answer is clear enough.

Enea.


On 02/25/2016 07:17 PM, Rao,Nakul I wrote:
> Hi
> I am using Parma Polyhedra library in a Formal Verification project. I 
> was unable to find a function that computes the complement of a 
> logical equation.
> For example, complement of a=5 will be a!=5.
> Could you tell me how I could do this.
> Thanks and Regards
> Nakul
>
>
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> PPL-devel at cs.unipr.it
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