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add unsat core, activity, quick pass for viable

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This commit is contained in:
Nikolaj Bjorner 2021-11-24 13:23:28 +01:00
parent b82c3cfd33
commit caef8d026f
6 changed files with 91 additions and 43 deletions
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51
src/math/polysat/solver.cpp
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@ -147,7 +147,6 @@ namespace polysat {
#endif
}
bool solver::can_propagate() {
return m_qhead < m_search.size() && !is_conflict();
}
@ -175,6 +174,8 @@ namespace polysat {
LOG_H2("Propagate bool " << lit << "@" << m_bvars.level(lit) << " " << m_level << " qhead: " << m_qhead);
signed_constraint c = lit2cnstr(lit);
SASSERT(c);
if (c->is_active())
return;
activate_constraint(c);
auto& wlist = m_bvars.watch(~lit);
unsigned i = 0, j = 0, sz = wlist.size();
@ -460,8 +461,7 @@ namespace polysat {
* viable solutions by excluding the previous guess.
*
*/
void solver::resolve_conflict() {
IF_VERBOSE(1, verbose_stream() << "resolve conflict\n");
void solver::resolve_conflict() {
LOG_H2("Resolve conflict");
LOG("\n" << *this);
LOG("search state: " << m_search);
@ -521,6 +521,36 @@ namespace polysat {
return m_conflict.resolve_value(v);
}
/**
* Variable activity accounting.
* As a placeholder we increment activity
* 1. when a variable assignment is used in a conflict.
* 2. when a variable propagation is resolved against.
* The hypothesis that this is useful should be tested against a
* broader suite of benchmarks and tested with micro-benchmarks.
* It should be tested in conjunction with restarts.
*/
void solver::inc_activity(pvar v) {
unsigned& act = m_activity[v];
act += m_activity_inc;
m_free_pvars.activity_increased_eh(v);
if (act > (1 << 24))
rescale_activity();
}
void solver::decay_activity() {
m_activity_inc *= m_variable_decay;
m_activity_inc /= 100;
}
void solver::rescale_activity() {
for (unsigned& act : m_activity) {
act >>= 14;
}
m_activity_inc >>= 14;
}
/** Conflict resolution case where boolean literal 'lit' is on top of the stack
* NOTE: boolean resolution should work normally even in bailout mode.
*/
@ -537,17 +567,12 @@ namespace polysat {
}
void solver::unsat_core(unsigned_vector& deps) {
NOT_IMPLEMENTED_YET(); // TODO: needs to be fixed to work with conflict_core
/*
deps.reset();
p_dependency_ref conflict_dep(m_dm);
for (auto& c : m_conflict.units())
if (c)
conflict_dep = m_dm.mk_join(c->unit_dep(), conflict_dep);
for (auto& c : m_conflict.clauses())
conflict_dep = m_dm.mk_join(c->dep(), conflict_dep);
m_dm.linearize(conflict_dep, deps);
*/
for (auto c : m_conflict) {
auto d = m_bvars.dep(c.blit());
if (d != null_dependency)
deps.push_back(d);
}
}
void solver::learn_lemma(clause& lemma) {