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Division monotonicity

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This commit is contained in:
Clemens Eisenhofer 2023-02-01 11:27:46 +01:00
parent 63f7001117
commit 8db575ea3b
2 changed files with 56 additions and 5 deletions
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60
src/math/polysat/saturation.cpp
View file

@ -42,20 +42,24 @@ namespace polysat {
void saturation::perform(pvar v, conflict& core) {
IF_VERBOSE(2, verbose_stream() << "v" << v << " " << core << "\n");
for (auto c : core)
if (perform(v, c, core))
return;
//if (perform(v, c, core)) Why stop eagerly?
// return;
perform(v, c, core);
}
bool saturation::perform(pvar v, signed_constraint const& c, conflict& core) {
if (c.is_currently_true(s))
return false;
bool prop = try_div_monotonicity(core); // check independent of the conflicting constraint
if (c->is_ule()) {
auto i = inequality::from_ule(c);
return try_inequality(v, i, core);
return try_inequality(v, i, core) | prop;
}
if (c->is_umul_ovfl())
return try_umul_ovfl(v, c, core);
return try_umul_ovfl(v, c, core) | prop;
return false;
}
@ -1933,7 +1937,53 @@ namespace polysat {
return false;
}
/**
* let q1 = x1 / y1, q2 = x2 / y2
* x1 <= x2 /\ y1 >= y2 => q1 <= q2
*/
bool saturation::try_div_monotonicity(conflict& core) {
set_rule("[x1, y1, x2, y2] x1 <= x2 & y1 <= y2 => x1 / y1 <= x2 / y2");
bool propagated = false;
for (auto it1 = s.m_constraints.begin_div(); it1 < s.m_constraints.end_div(); it1++) {
auto [x1, y1, q1, r1] = *it1;
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;
q1_val = s.get_value(q1);
rational expected1 = y1_val.is_zero() ? y1.manager().max_value() : div(x1_val, y1_val);
if (q1_val == expected1)
continue;
for (auto it2 = s.m_constraints.begin_div(); it2 < s.m_constraints.end_div(); it2++) {
if (it1 == it2)
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);
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)));
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)));
propagated = true;
}
}
}
return propagated;
}
/*
* TODO
*

1
src/math/polysat/saturation.h
View file

@ -70,6 +70,7 @@ namespace polysat {
bool try_add_mul_bound(pvar x, conflict& core, inequality const& axb_l_y);
bool try_add_mul_bound2(pvar x, conflict& core, inequality const& axb_l_y);
bool try_infer_parity_equality(pvar x, conflict& core, inequality const& a_l_b);
bool try_div_monotonicity(conflict& core);
rational round(rational const& M, rational const& x);
bool extract_linear_form(pdd const& q, pvar& y, rational& a, rational& b);