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reorg resolution loop

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2021-04-01 14:46:18 -07:00
parent 303c41395d
commit 018835f1db
2 changed files with 34 additions and 20 deletions
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47
src/math/polysat/polysat.cpp
View file

@ -366,25 +366,23 @@ namespace polysat {
v = m_search[i];
if (!is_marked(v))
continue;
justification& j = m_justification[v];
if (j.level() <= base_level()) {
report_unsat();
return;
}
pdd r = resolve(v, p);
pdd rval = r.subst_val(sub);
if (!rval.is_non_zero()) {
backtrack();
backtrack(i);
return;
}
if (r.is_val()) {
// TBD: UNSAT, set conflict
SASSERT(!r.is_zero());
// learn_lemma(r, deps);
report_unsat();
return;
}
justification& j = m_justification[v];
if (j.is_decision()) {
// TBD: revert value and add constraint
// propagate if new value is given uniquely
// set conflict if viable set is empty
// adding r and reverting last decision.
// m_search.size() - i;
revert_decision(i);
return;
}
SASSERT(j.is_propagation());
@ -393,14 +391,15 @@ namespace polysat {
set_mark(w);
p = r;
}
UNREACHABLE();
report_unsat();
}
void solver::backtrack() {
unsigned i = m_search.size();
void solver::backtrack(unsigned i) {
do {
auto v = m_search[i];
justification& j = m_justification[v];
if (j.level() <= base_level())
break;
if (j.is_decision()) {
// TBD: flip last decision.
// subtract value from viable
@ -414,17 +413,25 @@ namespace polysat {
}
}
while (i-- > 0);
// unsat
// r = 1;
// learn_and_backjump(r, m_search.size());
report_unsat();
}
void solver::report_unsat() {
// dependencies for variables that are currently marked and below base level
// are in the unsat core that is produced as a side-effect
}
void solver::revert_decision(unsigned i) {
}
void solver::learn_and_backjump(pdd const& lemma, unsigned new_level) {
unsigned num_levels = m_level - new_level;
SASSERT(num_levels > 0);
pop_levels(num_levels);
m_trail.pop_scope(num_levels);
// TBD: add new constraints & lemmas.
}
@ -489,7 +496,11 @@ namespace polysat {
}
bool solver::at_base_level() const {
return m_level == 0 || (!m_scopes.empty() && m_level == m_scopes.back());
return m_level == base_level();
}
unsigned solver::base_level() const {
return m_scopes.empty() ? 0 : m_scopes.back();
}
std::ostream& solver::display(std::ostream& out) const {

7
src/math/polysat/polysat.h
View file

@ -120,7 +120,7 @@ namespace polysat {
unsigned m_qhead { 0 };
unsigned m_level { 0 };
unsigned_vector m_scopes; // user-scopes. External clients can push/pop scope
unsigned_vector m_scopes; // user-scopes. External clients can push/pop scope.
// conflict state
@ -174,9 +174,12 @@ namespace polysat {
bool is_conflict() const { return nullptr != m_conflict; }
bool at_base_level() const;
unsigned base_level() const;
void resolve_conflict();
void backtrack();
void backtrack(unsigned i);
void report_unsat();
void revert_decision(unsigned i);
void learn_and_backjump(pdd const& lemma, unsigned new_level);
bool can_decide() const { return !m_free_vars.empty(); }