mirrors/z3
3
0
Fork 0
mirror of https://github.com/Z3Prover/z3 synced 2025-08-23 03:27:52 +00:00
Code Activity

pareto2

Browse source 
Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2014-01-01 22:32:27 -08:00
parent af27efbf4a
commit 8883234647
3 changed files with 98 additions and 23 deletions
Download patch file Download diff file Expand all files Collapse all files

49
src/opt/optsmt.cpp
View file

@ -273,6 +273,55 @@ namespace opt {
return l_true;
}
lbool optsmt::pareto(unsigned obj_index) {
lbool is_sat = l_true;
expr_ref block(m);
for (unsigned i = 0; i < m_lower.size(); ++i) {
m_lower[i] = inf_eps(rational(-1),inf_rational(0));
m_upper[i] = inf_eps(rational(1), inf_rational(0));
}
bool was_sat = false;
while (is_sat == l_true && !m_cancel) {
is_sat = m_s->check_sat(0, 0);
if (is_sat != l_true) break;
was_sat = true;
m_s->maximize_objective(obj_index);
m_s->get_model(m_model);
inf_eps obj = m_s->get_objective_value(obj_index);
if (obj > m_lower[obj_index]) {
m_lower[obj_index] = obj;
IF_VERBOSE(1, verbose_stream() << "(optsmt lower bound: " << obj << ")\n";);
}
block = m_s->mk_gt(obj_index, obj);
m_s->assert_expr(block);
}
if (m_cancel || is_sat == l_undef) {
return l_undef;
}
if (!was_sat) {
return l_false;
}
// set the solution tight.
// and set lower bounds on other values.
m_upper[obj_index] = m_lower[obj_index];
expr_ref val(m);
rational r;
arith_util a(m);
for (unsigned i = 0; i < m_lower.size(); ++i) {
if (i != obj_index) {
VERIFY(m_model->eval(m_objs[i].get(), val) && a.is_numeral(val, r));
m_lower[i] = inf_eps(r);
}
}
return l_true;
}
/**
Takes solver with hard constraints added.
Returns an optimal assignment to objective functions.