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fix todo on enforcing premises

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2021-09-22 12:26:45 -07:00
parent e5df395380
commit 3447d80310
4 changed files with 64 additions and 55 deletions
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61
src/math/polysat/explain.cpp
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@ -46,48 +46,65 @@ namespace polysat {
// c2 ... constraint that is currently false
// Try to replace it with a new false constraint (derived from superposition with a true constraint)
signed_constraint ex_polynomial_superposition::find_replacement(signed_constraint c2, pvar v, conflict& core) {
lbool ex_polynomial_superposition::find_replacement(signed_constraint c2, pvar v, conflict& core) {
vector<signed_constraint> premises;
for (auto c1 : core) {
if (!is_positive_equality_over(v, c1))
continue;
if (!c1.is_currently_true(s()))
continue;
signed_constraint c = resolve1(v, c1, c2);
if (!c)
continue;
vector<signed_constraint> premises;
premises.push_back(c1);
premises.push_back(c2);
core.replace(c2, c, std::move(premises));
return c;
if (!c->has_bvar())
s().m_constraints.ensure_bvar(c.get());
switch (c.bvalue(s())) {
case l_false:
// new conflict state based on propagation and theory conflict
core.reset();
core.insert(c1);
core.insert(c2);
core.insert(~c);
return l_true;
case l_undef:
// Ensure that c is assigned and justified
premises.push_back(c1);
premises.push_back(c2);
core.replace(c2, c, premises);
SASSERT(l_true == c.bvalue(s()));
SASSERT(c.is_currently_false(s()));
break;
default:
break;
}
// NOTE: more variables than just 'v' might have been removed here (see polysat::test_p3).
// c alone (+ variables) is now enough to represent the conflict.
core.reset();
core.set(c);
return c->contains_var(v) ? l_undef : l_true;
}
return {};
return l_false;
}
// TODO(later): check superposition into disequality again (see notes)
// true = done, false = abort, undef = continue
// TODO: can try multiple replacements at once; then the c2 loop needs to be done only once... (requires some reorganization for storing the premises)
lbool ex_polynomial_superposition::try_explain1(pvar v, conflict& core) {
for (auto c2 : core) {
if (!is_positive_equality_over(v, c2))
continue;
if (!c2.is_currently_false(s()))
continue;
// TODO: can try multiple replacements at once; then the c2 loop needs to be done only once... (requires some reorganization for storing the premises)
signed_constraint c = find_replacement(c2, v, core);
if (!c)
continue;
if (c->contains_var(v))
switch (find_replacement(c2, v, core)) {
case l_undef:
return l_undef;
if (!c->has_bvar() || l_undef == c.bvalue(s()))
core.keep(c); // adds propagation of c to the search stack
// NOTE: more variables than just 'v' might have been removed here (see polysat::test_p3).
// c alone (+ variables) is now enough to represent the conflict.
core.reset();
core.set(c);
return l_true;
case l_true:
return l_true;
case l_false:
continue;
}
}
return l_false;
}