mirrors/z3
3
0
Fork 0
mirror of https://github.com/Z3Prover/z3 synced 2025-04-29 03:45:51 +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

70
src/opt/opt_context.cpp
View file

@ -173,33 +173,48 @@ namespace opt {
lbool context::execute_pareto() {
opt_solver& s = get_solver();
arith_util a(m);
lbool is_sat = execute_box();
if (is_sat != l_true) return is_sat;
// check if solution is bounded
bounds_t bound;
expr_ref val(m);
rational r;
lbool is_sat = l_true;
vector<bounds_t> bounds;
for (unsigned i = 0; i < m_objectives.size(); ++i) {
objective const& obj = m_objectives[i];
if (obj.m_type == O_MAXSMT) {
IF_VERBOSE(0, verbose_stream() << "Pareto optimization is not supported for MAXSMT\n";);
return l_undef;
}
inf_eps lo = get_lower_as_num(i);
inf_eps hi = get_upper_as_num(i);
if (!hi.is_finite()) {
IF_VERBOSE(0, verbose_stream() << "Objective " << i << " has no upper bound\n";);
solver::scoped_push _sp(s);
is_sat = m_optsmt.pareto(obj.m_index);
if (is_sat != l_true) {
return is_sat;
}
if (!m_optsmt.get_upper(obj.m_index).is_finite()) {
return l_undef;
}
if (!lo.is_finite()) {
IF_VERBOSE(0, verbose_stream() << "Objective " << i << " has no lower bound\n";);
return l_undef;
}
bound.push_back(std::make_pair(lo, hi));
bounds_t bound;
for (unsigned j = 0; j < m_objectives.size(); ++j) {
objective const& obj_j = m_objectives[j];
inf_eps lo = m_optsmt.get_lower(obj_j.m_index);
inf_eps hi = m_optsmt.get_upper(obj_j.m_index);
bound.push_back(std::make_pair(lo, hi));
}
bounds.push_back(bound);
}
vector<bounds_t> bounds;
bounds.push_back(bound);
display_bounds(verbose_stream(), bound);
opt_solver& s = get_solver();
for (unsigned i = 0; i < bounds.size(); ++i) {
for (unsigned j = 0; j < bounds.size(); ++j) {
objective const& obj = m_objectives[j];
if (obj.m_type == O_MAXIMIZE) {
bounds[i][j].second = bounds[j][j].second;
}
else {
bounds[i][j].first = bounds[j][j].first;
}
}
display_bounds(verbose_stream() << "new bound\n", bounds[i]);
}
for (unsigned i = 0; i < bounds.size(); ++i) {
bounds_t b = bounds[i];
vector<inf_eps> mids;
@ -211,17 +226,26 @@ namespace opt {
expr_ref ge = s.mk_ge(obj.m_index, mid);
s.assert_expr(ge);
}
is_sat = s.check_sat_core(0, 0);
is_sat = execute_box();
switch(is_sat) {
case l_undef:
return is_sat;
case l_true:
case l_true: {
bool at_bound = true;
for (unsigned j = 0; j < b.size(); ++j) {
b[j] = std::make_pair(b[j].first, mids[j]);
objective const& obj = m_objectives[j];
if (m_model->eval(obj.m_term, val) && a.is_numeral(val, r)) {
mids[j] = inf_eps(r);
}
at_bound = at_bound && mids[j] == b[j].second;
b[j].second = mids[j];
}
display_bounds(verbose_stream() << "new bound\n", b);
if (!at_bound) {
bounds.push_back(b);
}
display_bounds(verbose_stream(), b);
bounds.push_back(b);
break;
}
case l_false: {
bounds_t b2(b);
for (unsigned j = 0; j < b.size(); ++j) {
@ -229,7 +253,7 @@ namespace opt {
if (j > 0) {
b2[j-1].second = b[j-1].second;
}
display_bounds(verbose_stream(), b2);
display_bounds(verbose_stream() << "new bound\n", b2);
bounds.push_back(b2);
}
break;

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.

2
src/opt/optsmt.h
View file

@ -47,6 +47,8 @@ namespace opt {
lbool lex(unsigned obj_index);
lbool pareto(unsigned obj_index);
unsigned add(app* t, bool is_max);
void set_cancel(bool f);