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This commit is contained in:
Nikolaj Bjorner 2021-10-04 14:43:33 -07:00
parent fd8b2ba596
commit 813674087e
8 changed files with 134 additions and 83 deletions
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47
src/math/polysat/forbidden_intervals.cpp
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@ -28,7 +28,7 @@ namespace polysat {
struct fi_record {
eval_interval interval;
signed_constraint neg_cond; // could be multiple constraints later
vector<signed_constraint> side_cond;
signed_constraint src;
};
@ -75,10 +75,10 @@ namespace polysat {
* We assume that neg_cond is a consequence of src that
* does not mention the variable v to be eliminated.
*/
void forbidden_intervals::full_interval_conflict(signed_constraint src, signed_constraint neg_cond, conflict& core) {
SASSERT(neg_cond);
void forbidden_intervals::full_interval_conflict(signed_constraint src, vector<signed_constraint> const& side_cond, conflict& core) {
core.reset();
core.insert(~neg_cond);
for (auto c : side_cond)
core.insert(c);
core.insert(src);
core.set_bailout();
}
@ -92,16 +92,16 @@ namespace polysat {
for (signed_constraint c : just) {
LOG_H3("Computing forbidden interval for: " << c);
eval_interval interval = eval_interval::full();
signed_constraint neg_cond;
if (get_interval(c, v, interval, neg_cond)) {
vector<signed_constraint> side_cond;
if (get_interval(c, v, interval, side_cond)) {
LOG("interval: " << interval);
LOG("neg_cond: " << neg_cond);
LOG("neg_cond: " << side_cond);
if (interval.is_currently_empty())
continue;
if (interval.is_full()) {
// We have a single interval covering the whole domain
// => the side conditions of that interval are enough to produce a conflict
full_interval_conflict(c, neg_cond, core);
full_interval_conflict(c, side_cond, core);
revert_core(core);
return true;
}
@ -112,7 +112,7 @@ namespace polysat {
longest_i = records.size();
}
}
records.push_back({ std::move(interval), std::move(neg_cond), c });
records.push_back({ std::move(interval), std::move(side_cond), c });
}
}
@ -164,9 +164,8 @@ namespace polysat {
core.insert(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?
signed_constraint& neg_cond = records[i].neg_cond;
if (neg_cond)
core.insert(~neg_cond);
for (auto sc : records[i].side_cond)
core.insert(sc);
core.insert(records[i].src);
}
@ -183,7 +182,7 @@ namespace polysat {
* \returns True iff a forbidden interval exists and the output parameters were set.
*/
bool forbidden_intervals::get_interval(signed_constraint const& c, pvar v, eval_interval& out_interval, signed_constraint& out_neg_cond)
bool forbidden_intervals::get_interval(signed_constraint const& c, pvar v, eval_interval& out_interval, vector<signed_constraint>& out_side_cond)
{
if (!c->is_ule())
return false;
@ -232,10 +231,19 @@ namespace polysat {
// test_monot_bounds(8)
//
// Currently only works if coefficient is a power of two
if (!p1.is_val())
return false;
if (!p2.is_val())
return false;
if (!p1.is_val()) {
pdd q1 = p1.subst_val(s.assignment());
if (!q1.is_val())
return false;
out_side_cond.push_back(s.eq(q1, p1));
}
if (!p2.is_val()) {
pdd q2 = p2.subst_val(s.assignment());
if (!q2.is_val())
return false;
out_side_cond.push_back(s.eq(q2, p2));
p2 = q2;
}
rational a1 = p1.val();
rational a2 = p2.val();
// TODO: to express the interval for coefficient 2^i symbolically, we need right-shift/upper-bits-extract in the language.
@ -320,12 +328,11 @@ namespace polysat {
if (condition_body.is_val()) {
// Condition is trivial; no need to create a constraint for that.
SASSERT(is_trivial == condition_body.is_zero());
out_neg_cond = nullptr;
}
else if (is_trivial)
out_neg_cond = ~s.m_constraints.eq(condition_body);
out_side_cond.push_back(s.m_constraints.eq(condition_body));
else
out_neg_cond = s.m_constraints.eq(condition_body);
out_side_cond.push_back(~s.m_constraints.eq(condition_body));
if (is_trivial) {
if (c.is_positive())