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Move unfinished make_asserting code

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This commit is contained in:
Jakob Rath 2022-09-28 16:42:28 +02:00
parent 0dae3bad6a
commit 8d803a1266
5 changed files with 127 additions and 116 deletions
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10
src/math/polysat/interval.h
View file

@ -118,6 +118,14 @@ namespace polysat {
return false;
}
#if 0
// TODO: intersection of wrapping intervals might not be an interval!!!
//
// Example:
// [---------[
// -----[ [----
// would give
// [-[ [--[
eval_interval intersect(eval_interval const& other) const {
if (is_full()) return other;
if (other.is_full()) return *this;
@ -138,6 +146,8 @@ namespace polysat {
return eval_interval::proper(i_lo, i_lo_val, i_hi, i_hi_val);
}
#endif
};
inline std::ostream& operator<<(std::ostream& os, eval_interval const& i) {

113
src/math/polysat/simplify_clause.cpp
View file

@ -225,4 +225,117 @@ namespace polysat {
return true;
}
#if 0
// All variables of clause 'cl' except 'z' are assigned.
// Goal: a possibly weaker clause that implies a restriction on z around z_val
clause_ref simplify_clause::make_asserting(clause& cl, pvar z, rational z_val) {
signed_constraints cz; // constraints of 'cl' that contain 'z'
sat::literal_vector lits; // literals of the new clause
for (sat::literal lit : cl) {
signed_constraint c = s.lit2cnstr(lit);
if (c.contains_var(z))
cz.push_back(c);
else
lits.push_back(lit);
}
SASSERT(!cz.empty());
if (cz.size() == 1) {
// TODO: even in this case, if the constraint is non-linear in z, we might want to extract a maximal forbidden interval around z_val.
return nullptr;
}
else {
// multiple constraints that contain z
find_implied_constraint(cz, z, z_val, lits);
return clause::from_literals(std::move(lits));
}
}
// Each constraint in 'cz' is univariate in 'z' under the current assignment.
// Goal: a literal that is implied by the disjunction of cz and ensures z != z_val in viable.
// (plus side conditions that do not depend on z)
void simplify_clause::find_implied_constraint(signed_constraints const& cz, pvar z, rational z_val, sat::literal_vector& out_lits)
{
unsigned const out_lits_original_size = out_lits.size();
forbidden_intervals fi(s);
fi_record entry;
auto intersection = eval_interval::full();
bool all_unit = true;
for (signed_constraint const& c : cz) {
if (fi.get_interval(c, z, entry) && entry.coeff == 1) {
intersection = intersection.intersect(entry.interval);
for (auto const& sc : entry.side_cond)
out_lits.push_back(sc.blit());
} else {
all_unit = false;
break;
}
}
if (all_unit) {
SASSERT(!intersection.is_currently_empty());
// Unit intervals from all constraints
// => build constraint from intersection of forbidden intervals
// z \not\in [l;u[ <=> z - l >= u - l
if (intersection.is_proper()) {
auto c_new = s.ule(intersection.hi() - intersection.lo(), z - intersection.lo());
out_lits.push_back(c_new.blit());
}
} else {
out_lits.shrink(out_lits_original_size);
find_implied_constraint_sat(cz, z, z_val, out_lits);
}
}
void simplify_clause::find_implied_constraint_sat(signed_constraints const& cz, pvar z, rational z_val, sat::literal_vector& out_lits)
{
unsigned bit_width = s.size(z);
auto p_factory = mk_univariate_bitblast_factory();
auto p_us = (*p_factory)(bit_width);
auto& us = *p_us;
// Find max z1 such that z1 < z_val and all cz true under z := z1 (and current assignment)
rational z1 = z_val;
for (signed_constraint const& c : cz)
c.add_to_univariate_solver(s, us, 0);
us.add_ult_const(z_val, false, 0); // z1 < z_val
// First check if any such z1 exists
switch (us.check()) {
case l_false:
// No such z1 exists
z1 = s.m_pdd[z]->max_value(); // -1
break;
case l_true:
// z1 exists. Try to make it as small as possible by setting bits to 0
for (unsigned j = bit_width; j-- > 0; ) {
switch (us.check()) {
case l_true:
// TODO
break;
case l_false:
// TODO
break;
default:
UNREACHABLE(); // TODO: see below
}
}
break;
default:
UNREACHABLE(); // TODO: should we link the child solver's resources to polysat's resource counter?
}
// Find min z2 such that z2 > z_val and all cz true under z := z2 (and current assignment)
// TODO
}
#endif
}

4
src/math/polysat/simplify_clause.h
View file

@ -36,6 +36,10 @@ namespace polysat {
pdd abstract(pdd const& p, pdd& v);
clause_ref make_asserting(clause& cl, pvar z, rational z_val);
void find_implied_constraint(signed_constraints const& cz, pvar z, rational z_val, sat::literal_vector& out_lits);
void find_implied_constraint_sat(signed_constraints const& cz, pvar z, rational z_val, sat::literal_vector& out_lits);
public:
simplify_clause(solver& s);

112
src/math/polysat/solver.cpp
View file

@ -1158,116 +1158,4 @@ namespace polysat {
return all_ok;
}
// All variables of clause 'cl' except 'z' are assigned.
// Goal: a possibly weaker clause that implies a restriction on z around z_val
clause_ref solver::make_asserting(clause& cl, pvar z, rational z_val) {
signed_constraints cz; // constraints of 'cl' that contain 'z'
sat::literal_vector lits; // literals of the new clause
for (sat::literal lit : cl) {
signed_constraint c = lit2cnstr(lit);
if (c.contains_var(z))
cz.push_back(c);
else
lits.push_back(lit);
}
SASSERT(!cz.empty());
if (cz.size() == 1) {
// TODO: even in this case, if the constraint is non-linear in z, we might want to extract a maximal forbidden interval around z_val.
return nullptr;
}
else {
// multiple constraints that contain z
find_implied_constraint(cz, z, z_val, lits);
return clause::from_literals(std::move(lits));
}
}
// Each constraint in 'cz' is univariate in 'z' under the current assignment.
// Goal: a literal that is implied by the disjunction of cz and ensures z != z_val in viable.
// (plus side conditions that do not depend on z)
void solver::find_implied_constraint(signed_constraints const& cz, pvar z, rational z_val, sat::literal_vector& out_lits)
{
unsigned const out_lits_original_size = out_lits.size();
forbidden_intervals fi(*this);
fi_record entry;
auto intersection = eval_interval::full();
bool all_unit = true;
for (signed_constraint const& c : cz) {
if (fi.get_interval(c, z, entry) && entry.coeff == 1) {
intersection = intersection.intersect(entry.interval);
for (auto const& sc : entry.side_cond)
out_lits.push_back(sc.blit());
} else {
all_unit = false;
break;
}
}
if (all_unit) {
SASSERT(!intersection.is_currently_empty());
// Unit intervals from all constraints
// => build constraint from intersection of forbidden intervals
// z \not\in [l;u[ <=> z - l >= u - l
if (intersection.is_proper()) {
auto c_new = ule(intersection.hi() - intersection.lo(), z - intersection.lo());
out_lits.push_back(c_new.blit());
}
} else {
out_lits.shrink(out_lits_original_size);
find_implied_constraint_sat(cz, z, z_val, out_lits);
}
}
void solver::find_implied_constraint_sat(signed_constraints const& cz, pvar z, rational z_val, sat::literal_vector& out_lits)
{
unsigned bit_width = size(z);
auto p_factory = mk_univariate_bitblast_factory();
auto p_us = (*p_factory)(bit_width);
auto& us = *p_us;
// Find max z1 such that z1 < z_val and all cz true under z := z1 (and current assignment)
rational z1 = z_val;
for (signed_constraint const& c : cz)
c.add_to_univariate_solver(*this, us, 0);
us.add_ult_const(z_val, false, 0); // z1 < z_val
// First check if any such z1 exists
switch (us.check()) {
case l_false:
// No such z1 exists
z1 = m_pdd[z]->max_value(); // -1
break;
case l_true:
// z1 exists. Try to make it as small as possible by setting bits to 0
for (unsigned j = bit_width; j-- > 0; ) {
switch (us.check()) {
case l_true:
// TODO
break;
case l_false:
// TODO
break;
default:
UNREACHABLE(); // TODO: see below
}
}
break;
default:
UNREACHABLE(); // TODO: should we link the child solver's resources to polysat's resource counter?
}
// Find min z2 such that z2 > z_val and all cz true under z := z2 (and current assignment)
// TODO
}
}

4
src/math/polysat/solver.h
View file

@ -234,10 +234,6 @@ namespace polysat {
bool can_propagate();
void propagate();
clause_ref make_asserting(clause& cl, pvar z, rational z_val);
void find_implied_constraint(signed_constraints const& cz, pvar z, rational z_val, sat::literal_vector& out_lits);
void find_implied_constraint_sat(signed_constraints const& cz, pvar z, rational z_val, sat::literal_vector& out_lits);
public:
/**