mirror of
https://github.com/Z3Prover/z3
synced 2025-04-29 03:45:51 +00:00
Polysat: forbidden intervals updates (#5230)
* Pop assign_eh * Fix scoped_ptr_vector constructors, add detach() * Need to copy the returned lemma * Add test * Basic inequality tests * Return disjunctive lemma to caller
This commit is contained in:
Jakob Rath
GitHub
parent
d6e41de344
commit
0c4824f194
9 changed files with 189 additions and 24 deletions
|
|
@ -62,6 +62,7 @@ namespace polysat {
|
|||
bool_var bvar() const { return m_bool_var; }
|
||||
bool sign() const { return m_sign; }
|
||||
void assign_eh(bool is_true) { m_status = (is_true ^ !m_sign) ? l_true : l_false; }
|
||||
void unassign_eh() { m_status = l_undef; }
|
||||
bool is_positive() const { return m_status == l_true; }
|
||||
bool is_negative() const { return m_status == l_false; }
|
||||
bool is_undef() const { return m_status == l_undef; }
|
||||
|
|
@ -69,6 +70,27 @@ namespace polysat {
|
|||
};
|
||||
|
||||
inline std::ostream& operator<<(std::ostream& out, constraint const& c) { return c.display(out); }
|
||||
|
||||
|
||||
class clause {
|
||||
scoped_ptr_vector<constraint> m_literals;
|
||||
public:
|
||||
clause() {}
|
||||
clause(scoped_ptr_vector<constraint>&& literals): m_literals(std::move(literals)) {
|
||||
SASSERT(std::all_of(m_literals.begin(), m_literals.end(), [](constraint* c) { return c != nullptr; }));
|
||||
SASSERT(empty() || std::all_of(m_literals.begin(), m_literals.end(), [this](constraint* c) { return c->level() == level(); }));
|
||||
}
|
||||
|
||||
bool empty() const { return m_literals.empty(); }
|
||||
unsigned size() const { return m_literals.size(); }
|
||||
constraint* operator[](unsigned idx) const { return m_literals[idx]; }
|
||||
|
||||
using const_iterator = typename scoped_ptr_vector<constraint>::const_iterator;
|
||||
const_iterator begin() const { return m_literals.begin(); }
|
||||
const_iterator end() const { return m_literals.end(); }
|
||||
|
||||
ptr_vector<constraint> detach() { return m_literals.detach(); }
|
||||
|
||||
unsigned level() const { SASSERT(!empty()); return m_literals[0]->level(); }
|
||||
};
|
||||
|
||||
}
|
||||
|
|
|
|||
|
|
@ -62,7 +62,7 @@ namespace polysat {
|
|||
return true;
|
||||
}
|
||||
|
||||
bool forbidden_intervals::explain(solver& s, ptr_vector<constraint> const& conflict, pvar v, scoped_ptr_vector<constraint>& out_lemma) {
|
||||
bool forbidden_intervals::explain(solver& s, ptr_vector<constraint> const& conflict, pvar v, clause& out_lemma) {
|
||||
|
||||
// Extract forbidden intervals from conflicting constraints
|
||||
vector<fi_record> records;
|
||||
|
|
@ -137,6 +137,7 @@ namespace polysat {
|
|||
// - the upper bound of each interval is contained in the next interval,
|
||||
// then the forbidden intervals cover the whole domain and we have a conflict.
|
||||
// We learn the negation of this conjunction.
|
||||
scoped_ptr_vector<constraint> literals;
|
||||
for (unsigned seq_i = seq.size(); seq_i-- > 0; ) {
|
||||
unsigned const i = seq[seq_i];
|
||||
unsigned const next_i = seq[(seq_i+1) % seq.size()];
|
||||
|
|
@ -149,14 +150,15 @@ namespace polysat {
|
|||
auto const& rhs = next_hi - next_lo;
|
||||
constraint* c = constraint::ult(lemma_lvl, s.m_next_bvar++, neg_t, lhs, rhs, lemma_dep);
|
||||
LOG("constraint: " << *c);
|
||||
out_lemma.push_back(c);
|
||||
literals.push_back(c);
|
||||
// Side conditions
|
||||
// TODO: check whether the condition is subsumed by c? maybe at the end do a "lemma reduction" step, to try and reduce branching?
|
||||
scoped_ptr<constraint>& cond = records[i].cond;
|
||||
if (cond)
|
||||
out_lemma.push_back(cond.detach());
|
||||
literals.push_back(cond.detach());
|
||||
}
|
||||
|
||||
out_lemma = std::move(literals);
|
||||
return true;
|
||||
}
|
||||
|
||||
|
|
|
|||
|
|
@ -23,7 +23,7 @@ namespace polysat {
|
|||
class forbidden_intervals {
|
||||
|
||||
public:
|
||||
static bool explain(solver& s, ptr_vector<constraint> const& conflict, pvar v, scoped_ptr_vector<constraint>& out_lemma);
|
||||
static bool explain(solver& s, ptr_vector<constraint> const& conflict, pvar v, clause& out_lemma);
|
||||
|
||||
};
|
||||
}
|
||||
|
|
|
|||
|
|
@ -102,7 +102,8 @@ namespace polysat {
|
|||
}
|
||||
|
||||
lbool solver::check_sat() {
|
||||
TRACE("polysat", tout << "check\n";);
|
||||
LOG("Starting");
|
||||
m_disjunctive_lemma.reset();
|
||||
while (m_lim.inc()) {
|
||||
LOG_H1("Next solving loop iteration");
|
||||
LOG("Free variables: " << m_free_vars);
|
||||
|
|
@ -114,7 +115,8 @@ namespace polysat {
|
|||
}
|
||||
});
|
||||
|
||||
if (is_conflict() && at_base_level()) { LOG_H2("UNSAT"); return l_false; }
|
||||
if (pending_disjunctive_lemma()) { LOG_H2("UNDEF (handle lemma externally)"); return l_undef; }
|
||||
else if (is_conflict() && at_base_level()) { LOG_H2("UNSAT"); return l_false; }
|
||||
else if (is_conflict()) resolve_conflict();
|
||||
else if (can_propagate()) propagate();
|
||||
else if (!can_decide()) { LOG_H2("SAT"); return l_true; }
|
||||
|
|
@ -141,7 +143,6 @@ namespace polysat {
|
|||
void solver::del_var() {
|
||||
// TODO also remove v from all learned constraints.
|
||||
pvar v = m_viable.size() - 1;
|
||||
m_free_vars.del_var_eh(v);
|
||||
m_viable.pop_back();
|
||||
m_cjust.pop_back();
|
||||
m_value.pop_back();
|
||||
|
|
@ -222,6 +223,8 @@ namespace polysat {
|
|||
}
|
||||
c->assign_eh(is_true);
|
||||
add_watch(*c);
|
||||
m_assign_eh_history.push_back(v);
|
||||
m_trail.push_back(trail_instr_t::assign_eh_i);
|
||||
c->narrow(*this);
|
||||
}
|
||||
|
||||
|
|
@ -263,6 +266,7 @@ namespace polysat {
|
|||
}
|
||||
|
||||
void solver::pop_levels(unsigned num_levels) {
|
||||
LOG("Pop " << num_levels << " levels; current level is " << m_level);
|
||||
while (num_levels > 0) {
|
||||
switch (m_trail.back()) {
|
||||
case trail_instr_t::qhead_i: {
|
||||
|
|
@ -297,6 +301,14 @@ namespace polysat {
|
|||
m_cjust_trail.pop_back();
|
||||
break;
|
||||
}
|
||||
case trail_instr_t::assign_eh_i: {
|
||||
auto bvar = m_assign_eh_history.back();
|
||||
constraint* c = get_bv2c(bvar);
|
||||
erase_watch(*c);
|
||||
c->unassign_eh();
|
||||
m_assign_eh_history.pop_back();
|
||||
break;
|
||||
}
|
||||
default:
|
||||
UNREACHABLE();
|
||||
}
|
||||
|
|
@ -375,7 +387,6 @@ namespace polysat {
|
|||
++m_stats.m_num_decisions;
|
||||
else
|
||||
++m_stats.m_num_propagations;
|
||||
TRACE("polysat", tout << "v" << v << " := " << val << " " << j << "\n";);
|
||||
LOG("pvar " << v << " := " << val << " by " << j);
|
||||
SASSERT(is_viable(v, val));
|
||||
m_value[v] = val;
|
||||
|
|
@ -385,15 +396,15 @@ namespace polysat {
|
|||
}
|
||||
|
||||
void solver::set_conflict(constraint& c) {
|
||||
LOG("conflict: " << c);
|
||||
SASSERT(m_conflict.empty());
|
||||
TRACE("polysat", tout << "conflict " << c << "\n";);
|
||||
m_conflict.push_back(&c);
|
||||
}
|
||||
|
||||
void solver::set_conflict(pvar v) {
|
||||
SASSERT(m_conflict.empty());
|
||||
m_conflict.append(m_cjust[v]);
|
||||
TRACE("polysat", tout << "conflict "; for (auto* c : m_conflict) tout << *c << "\n";);
|
||||
LOG("conflict for pvar " << v << ": " << m_conflict);
|
||||
if (m_cjust[v].empty())
|
||||
m_conflict.push_back(nullptr);
|
||||
}
|
||||
|
|
@ -440,14 +451,27 @@ namespace polysat {
|
|||
|
||||
if (conflict_var != null_var) {
|
||||
LOG_H2("Conflict due to empty viable set for pvar " << conflict_var);
|
||||
scoped_ptr_vector<constraint> disjunctive_lemma;
|
||||
if (forbidden_intervals::explain(*this, m_conflict, conflict_var, disjunctive_lemma)) {
|
||||
LOG_H3("Learning disjunctive lemma"); // << disjunctive_lemma);
|
||||
SASSERT(disjunctive_lemma.size() > 0);
|
||||
if (disjunctive_lemma.size() == 1) {
|
||||
clause new_lemma;
|
||||
if (forbidden_intervals::explain(*this, m_conflict, conflict_var, new_lemma)) {
|
||||
LOG_H3("Learning disjunctive lemma");
|
||||
SASSERT(new_lemma.size() > 0);
|
||||
if (new_lemma.size() == 1) {
|
||||
lemma = new_lemma.detach()[0];
|
||||
// TODO: continue normally?
|
||||
} else {
|
||||
// TODO: solver needs to return l_undef and allow external handling of disjunctive lemma
|
||||
SASSERT(m_disjunctive_lemma.empty());
|
||||
reset_marks();
|
||||
for (constraint* c : new_lemma) {
|
||||
m_disjunctive_lemma.push_back(c->bvar());
|
||||
insert_bv2c(c->bvar(), c);
|
||||
for (auto v : c->vars())
|
||||
set_mark(v);
|
||||
}
|
||||
m_redundant_clauses.push_back(std::move(new_lemma));
|
||||
backtrack(m_search.size()-1, lemma);
|
||||
SASSERT(pending_disjunctive_lemma());
|
||||
m_conflict.reset();
|
||||
return;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
|
@ -635,13 +659,15 @@ namespace polysat {
|
|||
}
|
||||
|
||||
void solver::push() {
|
||||
LOG("Push user scope");
|
||||
push_level();
|
||||
m_base_levels.push_back(m_level);
|
||||
}
|
||||
|
||||
void solver::pop(unsigned num_scopes) {
|
||||
unsigned base_level = m_base_levels[m_base_levels.size() - num_scopes];
|
||||
pop_levels(m_level - base_level - 1);
|
||||
LOG("Pop " << num_scopes << " user scopes; lowest popped level = " << base_level << "; current level = " << m_level);
|
||||
pop_levels(m_level - base_level + 1);
|
||||
}
|
||||
|
||||
bool solver::at_base_level() const {
|
||||
|
|
|
|||
|
|
@ -65,6 +65,10 @@ namespace polysat {
|
|||
// Per constraint state
|
||||
scoped_ptr_vector<constraint> m_constraints;
|
||||
scoped_ptr_vector<constraint> m_redundant;
|
||||
vector<clause> m_redundant_clauses;
|
||||
|
||||
bool_var_vector m_disjunctive_lemma;
|
||||
bool_var_vector m_assign_eh_history;
|
||||
|
||||
// Map boolean variables to constraints
|
||||
bool_var m_next_bvar = 2; // TODO: later, bool vars come from external supply
|
||||
|
|
@ -249,7 +253,8 @@ namespace polysat {
|
|||
* Returns the disjunctive lemma that should be learned,
|
||||
* or an empty vector if check_sat() terminated for a different reason.
|
||||
*/
|
||||
bool_var_vector get_lemma() { NOT_IMPLEMENTED_YET(); return {}; };
|
||||
bool_var_vector get_lemma() { return m_disjunctive_lemma; }
|
||||
bool pending_disjunctive_lemma() { return !m_disjunctive_lemma.empty(); }
|
||||
|
||||
/**
|
||||
* retrieve unsat core dependencies
|
||||
|
|
|
|||
|
|
@ -22,7 +22,8 @@ namespace polysat {
|
|||
inc_level_i,
|
||||
viable_i,
|
||||
assign_i,
|
||||
just_i
|
||||
just_i,
|
||||
assign_eh_i,
|
||||
};
|
||||
|
||||
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue