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fixes, tests

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This commit is contained in:
Nikolaj Bjorner 2021-09-25 08:38:48 -07:00
parent e6c413b249
commit a574eebd05
9 changed files with 110 additions and 48 deletions
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28
src/math/polysat/conflict.cpp
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@ -14,10 +14,6 @@ Notes:
TODO: try a final core reduction step or other core minimization
TODO: If we have e.g. 4x+y=2 and y=0, then we have a conflict no matter the value of x, so we should drop x=? from the core.
(works currently if x is unassigned; for other cases we would need extra info from constraint::is_currently_false)
note that we may have added too many variables: e.g., y disappears in x*y if x=0
TODO: revert(pvar v) is too weak.
It should apply saturation rules currently only available for propagated values.
@ -134,16 +130,22 @@ namespace polysat {
}
// NOTE: maybe we should skip intermediate steps and just collect the leaf premises for c?
// Ensure that c is assigned and justified
/**
* Premises can either be justified by a Clause or by a value assignment.
* Premises that are justified by value assignments are not assigned (the bvalue is l_undef)
* The justification for those premises are based on the free assigned variables.
*
* NOTE: maybe we should skip intermediate steps and just collect the leaf premises for c?
* Ensure that c is assigned and justified
*/
void conflict::insert(signed_constraint c, vector<signed_constraint> const& premises) {
insert(c);
keep(c);
clause_builder c_lemma(s);
for (auto premise : premises) {
LOG_H3("premise: " << premise);
keep(premise);
SASSERT(premise->has_bvar());
SASSERT(premise.bvalue(s) == l_true);
SASSERT(premise.bvalue(s) != l_false);
c_lemma.push(~premise.blit());
}
c_lemma.push(c.blit());
@ -278,15 +280,21 @@ namespace polysat {
return true;
}
std::cout << "vars " << m_vars << " contains: " << m_vars.contains(v) << "\n";
m_vars.remove(v);
for (auto c : cjust_v)
insert(c);
std::cout << "try explain v" << v << "\n";
for (auto* engine : ex_engines)
if (engine->try_explain(v, *this))
return true;
std::cout << "try elim v" << v << "\n";
// No value resolution method was successful => fall back to saturation and variable elimination
while (s.inc()) {
// TODO: as a last resort, substitute v by m_value[v]?
@ -296,7 +304,9 @@ namespace polysat {
break;
}
set_bailout();
m_vars.insert(v);
if (s.is_assigned(v))
m_vars.insert(v);
std::cout << "vars " << m_vars << "\n";
return false;
}