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maxlexN

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2019-01-25 20:01:38 -08:00
parent 1ed68906fa
commit 121211a51c
1 changed files with 70 additions and 19 deletions
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89
src/opt/maxlex.cpp
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@ -80,21 +80,23 @@ namespace opt {
}
void update_assignment(model_ref & mdl) {
bool prefix_defined = true;
bool first_undef = true, second_undef = false;
for (auto & soft : m_soft) {
if (!prefix_defined) {
set_value(soft, l_undef);
if (first_undef && soft.value != l_undef) {
continue;
}
switch (soft.value) {
case l_undef:
prefix_defined = mdl->is_true(soft.s);
set_value(soft, prefix_defined ? l_true : l_undef);
break;
case l_true:
break;
case l_false:
break;
first_undef = false;
if (soft.value != l_false) {
lbool v = mdl->is_true(soft.s) ? l_true : l_undef;;
if (v == l_undef) {
second_undef = true;
}
if (second_undef) {
soft.set_value(v);
}
else {
set_value(soft, v); // also update constraints
}
}
}
update_bounds();
@ -103,15 +105,9 @@ namespace opt {
void update_bounds() {
m_lower.reset();
m_upper.reset();
bool prefix_defined = true;
for (auto & soft : m_soft) {
if (!prefix_defined) {
m_upper += soft.weight;
continue;
}
switch (soft.value) {
case l_undef:
prefix_defined = false;
m_upper += soft.weight;
break;
case l_true:
@ -126,6 +122,9 @@ namespace opt {
}
void init() {
for (auto & soft : m_soft) {
soft.set_value(l_undef);
}
model_ref mdl;
s().get_model(mdl);
update_assignment(mdl);
@ -211,9 +210,20 @@ namespace opt {
// a, b is unsat, a, not b is unsat -> a is unsat
// b is unsat, a, not b is unsat -> not a, not b
set_value(soft, l_false);
// core1 = { b }
// core2 = { a, not b }
if (!core.contains(a)) {
set_value(soft2, l_false);
}
else {
// core1 = { a, b}
// core2 = { not_b }
core.reset();
s().get_unsat_core(core);
if (!core.contains(a)) {
set_value(soft2, l_true);
}
}
update_bounds();
break;
case l_undef:
@ -233,6 +243,47 @@ namespace opt {
return l_true;
}
// every time probing whether to include soft_i,
// include suffix that is known to be assignable to T
lbool maxlexN() {
unsigned sz = m_soft.size();
for (unsigned i = 0; i < sz; ++i) {
auto& soft = m_soft[i];
if (soft.value != l_undef) {
continue;
}
expr_ref_vector asms(m);
asms.push_back(soft.s);
for (unsigned j = i + 1; j < sz; ++j) {
auto& soft2 = m_soft[j];
if (soft2.value == l_true) {
asms.push_back(soft2.s);
}
}
lbool is_sat = s().check_sat(asms);
switch (is_sat) {
case l_true:
update_assignment();
SASSERT(soft.value == l_true);
break;
case l_false:
set_value(soft, l_false);
for (unsigned j = i + 1; j < sz; ++j) {
auto& soft2 = m_soft[j];
if (soft2.value != l_true) {
break;
}
assert_value(soft2);
}
update_bounds();
break;
case l_undef:
return l_undef;
}
}
return l_true;
}
public:
maxlex(maxsat_context& c, unsigned id, weights_t & ws, expr_ref_vector const& s):
@ -246,7 +297,7 @@ namespace opt {
lbool operator()() override {
init();
return maxlex1();
return maxlexN();
}