mirrors/z3
3
0
Fork 0
mirror of https://github.com/Z3Prover/z3 synced 2025-04-30 20:35:51 +00:00
Code Activity

forbidden interval update

Browse source 
Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2021-09-07 17:00:46 +02:00
parent e6c4ae19c6
commit a6643955e6
7 changed files with 192 additions and 242 deletions
Download patch file Download diff file Expand all files Collapse all files

60
src/math/polysat/eq_constraint.cpp
View file

@ -120,66 +120,6 @@ namespace polysat {
// }
/// Compute forbidden interval for equality constraint by considering it as p <=u 0 (or p >u 0 for disequality)
bool eq_constraint::forbidden_interval(solver& s, bool is_positive, pvar v, eval_interval& out_interval, signed_constraint& out_neg_cond)
{
// Current only works when degree(v) is at most one
unsigned const deg = p().degree(v);
if (deg > 1)
return false;
if (deg == 0) {
return false;
UNREACHABLE(); // this case is not useful for conflict resolution (but it could be handled in principle)
// i is empty or full, condition would be this constraint itself?
return true;
}
unsigned const sz = s.size(v);
dd::pdd_manager& m = s.sz2pdd(sz);
pdd p1 = m.zero();
pdd e1 = m.zero();
p().factor(v, 1, p1, e1);
pdd e2 = m.zero();
// Currently only works if coefficient is a power of two
if (!p1.is_val())
return false;
rational a1 = p1.val();
// TODO: to express the interval for coefficient 2^i symbolically, we need right-shift/upper-bits-extract in the language.
// So currently we can only do it if the coefficient is 1.
if (!a1.is_zero() && !a1.is_one())
return false;
/*
unsigned j1 = 0;
if (!a1.is_zero() && !a1.is_power_of_two(j1))
return false;
*/
// Concrete values of evaluable terms
auto e1s = e1.subst_val(s.assignment());
if (!e1s.is_val())
return false;
SASSERT(e1s.is_val());
// e1 + t <= 0, with t = 2^j1*y
// condition for empty/full: 0 == -1, never satisfied, so we always have a proper interval!
SASSERT(!a1.is_zero());
pdd lo = 1 - e1;
rational lo_val = (1 - e1s).val();
pdd hi = -e1;
rational hi_val = (-e1s).val();
if (!is_positive) {
swap(lo, hi);
lo_val.swap(hi_val);
}
out_interval = eval_interval::proper(lo, lo_val, hi, hi_val);
out_neg_cond = nullptr;
return true;
}
inequality eq_constraint::as_inequality(bool is_positive) const {
pdd zero = p() - p();
if (is_positive)