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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2021-04-03 17:26:54 -07:00
parent 31baab49c8
commit c2b213c049
3 changed files with 130 additions and 66 deletions
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75
src/math/polysat/polysat.cpp
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@ -45,6 +45,18 @@ namespace polysat {
return !b.is_false();
}
void solver::add_non_viable(unsigned var, rational const& val) {
bdd value = m_bdd.mk_true();
for (unsigned k = size(var); k-- > 0; )
value &= val.get_bit(k) ? m_bdd.mk_var(k) : m_bdd.mk_nvar(k);
m_viable[var] &= !value;
}
lbool solver::find_viable(unsigned var, rational & val) {
return l_false;
}
struct solver::t_del_var : public trail {
solver& s;
t_del_var(solver& s): s(s) {}
@ -55,6 +67,8 @@ namespace polysat {
solver::solver(trail_stack& s):
m_trail(s),
m_bdd(1000),
m_dep_manager(m_value_manager, m_alloc),
m_lemma_dep(nullptr, m_dep_manager),
m_free_vars(m_activity) {
}
@ -102,7 +116,8 @@ namespace polysat {
}
void solver::add_eq(pdd const& p, unsigned dep) {
constraint* c = constraint::eq(m_level, p, m_dep_manager.mk_leaf(dep));
p_dependency_ref d(m_dep_manager.mk_leaf(dep), m_dep_manager);
constraint* c = constraint::eq(m_level, p, d);
m_constraints.push_back(c);
add_watch(*c);
}
@ -135,7 +150,7 @@ namespace polysat {
void solver::assign(unsigned var, unsigned index, bool value, unsigned dep) {
m_viable[var] &= value ? m_bdd.mk_var(index) : m_bdd.mk_nvar(index);
m_trail.push(vector_value_trail<u_dependency*, false>(m_vdeps, var));
m_trail.push(vector_value_trail<p_dependency*, false>(m_vdeps, var));
m_vdeps[var] = m_dep_manager.mk_join(m_vdeps[var], m_dep_manager.mk_leaf(dep));
if (m_viable[var].is_false()) {
// TBD: set conflict
@ -357,8 +372,7 @@ namespace polysat {
m_conflict = nullptr;
pdd p = c.p();
m_lemma_level = c.level();
m_lemma_deps.reset();
m_lemma_deps.push_back(c.dep());
m_lemma_dep = c.dep();
unsigned new_lemma_level = 0;
reset_marks();
for (auto v : c.vars())
@ -442,29 +456,34 @@ namespace polysat {
auto v = m_search[i];
SASSERT(m_justification[v].is_decision());
SASSERT(m_lemma_level <= m_justification[v].level());
//
// TBD: convert m_lemma_deps into deps.
// the scope of the new constraint should be confined to
// m_lemma_level so could be below the current user scope.
// What to do in this case is TBD.
//
unsigned level = m_lemma_level;
u_dependency* deps = nullptr;
constraint* c = constraint::eq(level, p, deps);
constraint* c = constraint::eq(m_lemma_level, p, m_lemma_dep);
m_cjust[v].push_back(c);
add_lemma(c);
//
// TBD: remove current value from viable
// m_values[v]
//
// 1. undo levels until i
// 2. find a new decision if there is one,
// propagate if decision is singular,
// otherwise if there are no viable decisions, backjump
// and set a new conflict.
//
}
add_non_viable(v, m_value[v]);
// TBD conditions for when backjumping applies to be clarified.
unsigned new_level = m_justification[v].level();
backjump(new_level);
//
// find a new decision if there is one,
// propagate if decision is singular,
// otherwise if there are no viable decisions, backjump
// and set a new conflict.
//
rational value;
switch (find_viable(v, value)) {
case l_true:
// unit propagation
break;
case l_undef:
// branch
break;
case l_false:
// no viable.
break;
}
}
void solver::backjump(unsigned new_level) {
unsigned num_levels = m_level - new_level;
SASSERT(num_levels > 0);
@ -490,10 +509,6 @@ namespace polysat {
/**
* Return residue of superposing p and q with respect to v.
*
* TBD: should also collect dependencies (deps)
* and maximal level of constraints so learned lemma
* is given the appropriate level.
*/
pdd solver::resolve(unsigned v, pdd const& p, unsigned& resolve_level) {
resolve_level = 0;
@ -507,7 +522,7 @@ namespace polysat {
// add parity condition to presere falsification
degree = r.degree(v);
resolve_level = std::max(resolve_level, c->level());
m_lemma_deps.push_back(c->dep());
m_lemma_dep = m_dep_manager.mk_join(m_lemma_dep.get(), c->dep());
}
}
}
@ -538,14 +553,12 @@ namespace polysat {
void solver::push() {
push_level();
m_dep_manager.push_scope();
m_scopes.push_back(m_level);
}
void solver::pop(unsigned num_scopes) {
unsigned base_level = m_scopes[m_scopes.size() - num_scopes];
pop_levels(m_level - base_level - 1);
m_dep_manager.pop_scope(num_scopes);
}
bool solver::at_base_level() const {