[PPL-devel] Write constraints in JAVA interface as in C++ ?
Zell
zell08v at orange.fr
Tue Jul 31 11:47:46 CEST 2012
Dear all,
If I understand correctly, the input for a PPL solver is a linear
constraint system $C$, and the output is a (not always) optimal polyhedron
represented as linear constraints that cover the points satisfying the
original constraint system $C$.
My question is, to use the library in practice, what are we supposed to do
to convert Cousot's propagation-rule into a PPL's input which is a linear
constraint system. ( Sankaranarayanan gave an algorithm using dualization
and Farkas's lemma to compile a linear transition system into a constraint
system, however I think there should be other prefered ways to do that
because Sankaranarayanan's paper appeared later than PPL. )
Here is an example:
1 x=0;
2: while (x<10){
3: x = x+1;
4 }
5
Denote X[i] to be the set of possible values of 'x' at the program point
'i'. Then, the propagation-rule à la Cousot should be direct
X[1] = \emptyset
X[2] \supset {0} \union X[4]
X[3] \supset X2 \intersect (-\infinity, 10)
X[4] \supset {x+1 | x\in X[4]}
X[5] \supset X2 \intersect [10,\infinity)
How can we convert these set-constraints into PPL's input ?
Thanks for your ideas.
Zell.
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