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updates to saturation

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This commit is contained in:
Nikolaj Bjorner 2023-12-23 16:59:17 -08:00
parent fbbad72c29
commit 50358e43ed
6 changed files with 131 additions and 1913 deletions
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57
src/sat/smt/polysat/core.cpp
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@ -193,32 +193,7 @@ namespace polysat {
}
sat::check_result core::final_check() {
constraint_id conflict_idx = find_conflicting_constraint();
// If all constraints evaluate to true, we are done.
if (conflict_idx.is_null())
return sat::check_result::CR_DONE;
// Extract variables that are of level or above of conflicting constraint and contradict the constraint
auto vars = find_conflict_variables(conflict_idx);
saturation sat(*this);
for (auto v: vars)
if (sat.propagate(v, conflict_idx))
return sat::check_result::CR_CONTINUE;
// If no saturation propagation was possible, explain the conflict using the variable assignment.
m_unsat_core = explain_eval(get_constraint(conflict_idx));
m_unsat_core.push_back(conflict_idx);
propagate_unsat_core();
return sat::check_result::CR_CONTINUE;
}
/**
* Identify a conflicting constraint, if any, that evaluates to false under
* the current assignment.
*/
constraint_id core::find_conflicting_constraint() {
unsigned conflict_level = UINT_MAX;
unsigned n = 0;
constraint_id conflict_idx = { UINT_MAX };
for (auto idx : m_prop_queue) {
auto [sc, d, value] = m_constraint_index[idx.id];
@ -227,17 +202,25 @@ namespace polysat {
SASSERT(eval_value != l_undef);
if (eval_value == value)
continue;
auto explain = explain_eval(sc);
unsigned new_conflict_level = d.level();
for (auto idx2 : explain)
new_conflict_level = std::max(new_conflict_level, m_constraint_index[idx2.id].d.level());
if (0 == (m_rand() % (++n)))
conflict_idx = idx;
if (new_conflict_level >= conflict_level)
continue;
conflict_idx = idx;
conflict_level = new_conflict_level;
auto vars = find_conflict_variables(idx);
saturation sat(*this);
for (auto v : vars)
if (sat.resolve(v, conflict_idx))
return sat::check_result::CR_CONTINUE;
}
return conflict_idx;
// If all constraints evaluate to true, we are done.
if (conflict_idx.is_null())
return sat::check_result::CR_DONE;
// If no saturation propagation was possible, explain the conflict using the variable assignment.
m_unsat_core = explain_eval(get_constraint(conflict_idx));
m_unsat_core.push_back(conflict_idx);
propagate_unsat_core();
return sat::check_result::CR_CONTINUE;
}
/**
@ -397,6 +380,10 @@ namespace polysat {
s.get_fixed_bits(v, fixed_bits);
}
void core::get_subslices(pvar v, offset_slices& out) {
s.get_bitvector_sub_slices(v, out);
}
bool core::inconsistent() const {
return s.inconsistent();
}