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updates to try_div_monotonicity

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2023-02-04 15:55:14 -08:00
parent 539a4e4eae
commit b45f42133d
4 changed files with 77 additions and 41 deletions
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3
src/math/polysat/constraint_manager.h
View file

@ -132,8 +132,7 @@ namespace polysat {
constraint* const* begin() const { return m_constraints.data(); }
constraint* const* end() const { return m_constraints.data() + m_constraints.size(); }
std::tuple<pdd, pdd, pvar, pvar> const* begin_div() const { return m_dedup.m_div_rem_list.data(); }
std::tuple<pdd, pdd, pvar, pvar> const* end_div() const { return m_dedup.m_div_rem_list.data() + m_dedup.m_div_rem_list.size(); }
vector<std::tuple<pdd, pdd, pvar, pvar>> const& div_constraints() const { return m_dedup.m_div_rem_list; }
class clause_iterator {
friend class constraint_manager;

104
src/math/polysat/saturation.cpp
View file

@ -1956,12 +1956,69 @@ namespace polysat {
/**
* let q1 = x1 / y1, q2 = x2 / y2
* x1 <= x2 /\ y1 >= y2 => q1 <= q2
* x1 <= x2 & y1 >= y2 => q1 <= q2
* y1 <= y2 & q1 < q2 => (x2 - x1) >= (q2 - q1 - 1) * y1
*
* Limitation/assumption:
* Values of x1, y1, q1 have to be available for the rule to apply.
* If not all values are present, the rule isn't going to be used.
* The arithmetic solver uses complete assignments because it
* builds on top of an integer feasiable state (or feasible over rationals)
* Lemmas are false under that assignment. They don't necessarily propagate, though.
* PolySAT isn't (yet) set up to work with complete assignments and thereforce misses such lemmas.
* - should we force complete assignments by computing first a model that is feasible modulo linear constraints
* (ignore non-linear constraints in linear mode)?
* - should we detect forcing relations x1 <= x2, y2 <= y1 based on the constraints (not on assignments)?
* other saturation rules already do this, but it is highly syntactic whether they apply.
*
*
* Other rules:
* x < y div z => x * z < y
*
* Or just:
* (y div z) * z <= y,
* ~overfl((y div z) * z)
*
* ~overfl(x * y), z <= y => x * z <= x * y
*
*/
bool saturation::try_div_monotonicity(conflict& core) {
bool propagated = false;
for (auto it1 = s.m_constraints.begin_div(); it1 < s.m_constraints.end_div(); it1++) {
auto [x1, y1, q1, r1] = *it1;
auto log = [&](auto& x1, auto& x1_val, auto& y1, auto& y1_val, auto& q1, auto& q1_val,
auto& x2, auto& x2_val, auto& y2, auto& y2_val, auto& q2, auto& q2_val) {
IF_VERBOSE(1, verbose_stream() << "Division monotonicity: [" << x1 << "] (" << x1_val << ") / [" << y1 << "] (" << y1_val << ") = "
<< s.var(q1) << "\n");
};
auto monotonicity1 = [&](auto& x1, auto& x1_val, auto& y1, auto& y1_val, auto& q1, auto& q1_val,
auto& x2, auto& x2_val, auto& y2, auto& y2_val, auto& q2, auto& q2_val) {
if (!(x1_val <= x2_val && y1_val >= y2_val && q1_val > q2_val))
return;
propagated = true;
set_rule("[x1, y1, x2, y2] x1 <= x2 & y2 <= y1 => x1 / y1 <= x2 / y2");
log(x1, x1_val, y1, y1_val, q1, q1_val, x2, x2_val, y2, y2_val, q2, q2_val);
m_lemma.reset();
m_lemma.insert_eval(~s.ule(x1, x2));
m_lemma.insert_eval(~s.ule(y2, y1));
propagate(q1, core, s.ule(s.var(q1), s.var(q2)));
};
auto monotonicity2 = [&](auto& x1, auto& x1_val, auto& y1, auto& y1_val, auto& q1, auto& q1_val,
auto& x2, auto& x2_val, auto& y2, auto& y2_val, auto& q2, auto& q2_val) {
if (!(y1_val <= y2_val && q1_val < q2_val && (x2_val - x1_val < (q2_val - q1_val - 1) * y1_val)))
return;
propagated = true;
set_rule("[x1, y1, x2, y2] y2 >= y1 & q2 > q1 => x2 - x1 >= ((x2 / y2) - (x1 / y1) - 1) * y1");
log(x1, x1_val, y1, y1_val, q1, q1_val, x2, x2_val, y2, y2_val, q2, q2_val);
m_lemma.reset();
m_lemma.insert_eval(~s.uge(y2, y1));
m_lemma.insert_eval(~s.ult(s.var(q1), s.var(q2)));
propagate(q1, core, s.uge(x2 - x1, (s.var(q2) - s.var(q1) - 1) * y1));
};
for (auto const& [x1, y1, q1, r1] : s.m_constraints.div_constraints()) {
rational x1_val, y1_val, q1_val;
if (!s.try_eval(x1, x1_val) || !s.try_eval(y1, y1_val) || !s.is_assigned(q1))
continue;
@ -1970,45 +2027,18 @@ namespace polysat {
if (q1_val == expected1)
continue;
for (auto it2 = s.m_constraints.begin_div(); it2 < s.m_constraints.end_div(); it2++) {
if (it1 == it2)
for (auto const& [x2, y2, q2, r2] : s.m_constraints.div_constraints()) {
if (x1 == x2 && y1 == y2)
continue;
auto [x2, y2, q2, r2] = *it2;
rational x2_val, y2_val, q2_val;
if (!s.try_eval(x2, x2_val) || !s.try_eval(y2, y2_val) || !s.is_assigned(q2))
continue;
q2_val = s.get_value(q2);
set_rule("[x1, y1, x2, y2] x1 <= x2 & y1 <= y2 => x1 / y1 <= x2 / y2");
if (x1_val <= x2_val && y2_val <= y1_val && !(q1_val <= q2_val)) { // No special treatment for 0 required. It is already monotonic by SMTLib defining x / 0 = 2^k
m_lemma.reset();
m_lemma.insert_eval(~s.ule(x1, x2));
m_lemma.insert_eval(~s.ule(y2, y1));
propagate(q1, core, s.ule(s.var(q1), s.var(q2)));
//verbose_stream() << "1. #1 Division monotonicity: [" << x1 << "] (" << x1_val << ") / [" << y1 << "] (" << y1_val << ") = " << s.var(q1) << " (" << q1_val << ") rem: " << s.var(r1) << " (" << (s.is_assigned(r1) ? s.get_value(r1) : (rational)-2) << ")\n";
//verbose_stream() << "1. #2 Division monotonicity: [" << x2 << "] (" << x2_val << ") / [" << y2 << "] (" << y2_val << ") = " << s.var(q2) << " (" << q2_val << ") rem: " << s.var(r2) << " (" << (s.is_assigned(r2) ? s.get_value(r2) : (rational)-2) << ")\n";
propagated = true;
}
if (x1_val >= x2_val && y2_val >= y1_val && !(q1_val >= q2_val)) {
m_lemma.reset();
m_lemma.insert_eval(~s.uge(x1, x2));
m_lemma.insert_eval(~s.uge(y2, y1));
propagate(q1, core, s.uge(s.var(q1), s.var(q2)));
//verbose_stream() << "2. #1 Division monotonicity: [" << x1 << "] (" << x1_val << ") / [" << y1 << "] (" << y1_val << ") = " << s.var(q1) << " (" << q1_val << ") rem: " << s.var(r1) << " (" << (s.is_assigned(r1) ? s.get_value(r1) : (rational)-2) << ")\n";
//verbose_stream() << "2. #2 Division monotonicity: [" << x2 << "] (" << x2_val << ") / [" << y2 << "] (" << y2_val << ") = " << s.var(q2) << " (" << q2_val << ") rem: " << s.var(r2) << " (" << (s.is_assigned(r2) ? s.get_value(r2) : (rational)-2) << ")\n";
propagated = true;
}
set_rule("[x1, y1, x2, y2] y2 >= y1 & q2 > q1 => x2 - x1 >= ((x2 / y2) - (x1 / y1) - 1) * y1");
if (y2_val >= y1_val && q2_val > q1_val && !(x2_val - x1_val >= (q2_val - q1_val - 1) * y1_val)) {
m_lemma.reset();
m_lemma.insert_eval(~s.uge(y2, y1));
m_lemma.insert_eval(~s.ult(s.var(q1), s.var(q2)));
propagate(q1, core, s.uge(x2 - x1, (s.var(q2) - s.var(q1) - 1) * y1));
//verbose_stream() << "3. #1 Division monotonicity: [" << x1 << "] (" << x1_val << ") / [" << y1 << "] (" << y1_val << ") = " << s.var(q1) << " (" << q1_val << ") rem: " << s.var(r1) << " (" << (s.is_assigned(r1) ? s.get_value(r1) : (rational)-2) << ")\n";
//verbose_stream() << "3. #2 Division monotonicity: [" << x2 << "] (" << x2_val << ") / [" << y2 << "] (" << y2_val << ") = " << s.var(q2) << " (" << q2_val << ") rem: " << s.var(r2) << " (" << (s.is_assigned(r2) ? s.get_value(r2) : (rational)-2) << ")\n";
propagated = true;
}
monotonicity1(x1, x1_val, y1, y1_val, q1, q1_val, x2, x2_val, y2, y2_val, q2, q2_val);
monotonicity1(x2, x2_val, y2, y2_val, q2, q2_val, x1, x1_val, y1, y1_val, q1, q1_val);
monotonicity2(x1, x1_val, y1, y1_val, q1, q1_val, x2, x2_val, y2, y2_val, q2, q2_val);
monotonicity2(x2, x2_val, y2, y2_val, q2, q2_val, x1, x1_val, y1, y1_val, q1, q1_val);
}
}
return propagated;

9
src/math/polysat/solver.cpp
View file

@ -1312,8 +1312,7 @@ namespace polysat {
);
}
std::ostream& solver::display(std::ostream& out) const {
out << "Search Stack:\n";
std::ostream& solver::display_search(std::ostream& out) const {
for (auto item : m_search) {
if (item.is_assignment()) {
pvar v = item.var();
@ -1332,6 +1331,12 @@ namespace polysat {
out << "\n";
}
}
return out;
}
std::ostream& solver::display(std::ostream& out) const {
out << "Search Stack:\n";
display_search(out);
out << "Constraints:\n";
for (auto c : m_constraints)
out << "\t" << c->bvar2string() << ": " << *c << "\n";

2
src/math/polysat/solver.h
View file

@ -542,6 +542,8 @@ namespace polysat {
std::ostream& display(std::ostream& out) const;
std::ostream& display_search(std::ostream& out) const;
void collect_statistics(statistics& st) const;
params_ref const & params() const { return m_params; }