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more cleanup in nla_solver

Signed-off-by: Lev <levnach@hotmail.com>
This commit is contained in:
Lev 2018-10-15 22:37:09 -07:00 committed by Lev Nachmanson
parent 492abc1e57
commit 94448f36bb

View file

@ -269,63 +269,6 @@ struct solver::imp {
return static_cast<unsigned>(-1) != j;
}
// Return 0 if the var has to to have a zero value,
// -1 if the monomial has to be negative
// 1 if positive.
// If strict is true on the entrance then it can be set to false,
// otherwise it remains false
// Returns 2 if the sign is not defined.
int get_mon_sign_zero_var(unsigned j, bool & strict) {
if (m_monomials_containing_var.find(j) == m_monomials_containing_var.end())
return 2;
lpci lci = -1;
lpci uci = -1;
rational lb, ub;
bool lower_is_strict;
bool upper_is_strict;
m_lar_solver.has_lower_bound(j, lci, lb, lower_is_strict);
m_lar_solver.has_upper_bound(j, uci, ub, upper_is_strict);
if (is_set(uci) && is_set(lci) && ub == lb) {
if (ub.is_zero()){
m_expl->clear();
m_expl->push_justification(uci);
m_expl->push_justification(lci);
return 0;
}
m_expl->push_justification(uci);
m_expl->push_justification(lci);
return ub.is_pos() ? 1 : -1;
}
if (is_set(uci)) {
if (ub.is_neg()) {
m_expl->push_justification(uci);
return -1;
}
if (ub.is_zero()) {
strict = false;
m_expl->push_justification(uci);
return -1;
}
}
if (is_set(lci)) {
if (lb.is_pos()) {
m_expl->push_justification(lci);
return 1;
}
if (lb.is_zero()) {
strict = false;
m_expl->push_justification(lci);
return 1;
}
}
return 2; // the sign of the variable is not defined
}
bool var_is_fixed_to_zero(lpvar j) const {
return
m_lar_solver.column_has_upper_bound(j) &&
@ -381,78 +324,7 @@ struct solver::imp {
out << "\n";
return out;
}
/**
* \brief <return true if j is fixed to 1 or -1, and put the value into "sign">
*/
bool get_one_of_var(lpvar j, rational & sign) {
lpci lci;
lpci uci;
rational lb, ub;
bool is_strict;
if (!m_lar_solver.has_lower_bound(j, lci, lb, is_strict))
return false;
SASSERT(!is_strict);
if (!m_lar_solver.has_upper_bound(j, uci, ub, is_strict))
return false;
SASSERT(!is_strict);
if (ub == lb) {
if (ub == rational(1)) {
sign = rational(1);
}
else if (ub == -rational(1)) {
sign = rational(-1);
}
else
return false;
return true;
}
return false;
}
vector<mono_index_with_sign> get_ones_of_monomimal(const svector<lpvar> & vars) {
TRACE("nla_solver", tout << "get_ones_of_monomimal";);
vector<mono_index_with_sign> ret;
for (unsigned i = 0; i < vars.size(); i++) {
mono_index_with_sign mi;
if (get_one_of_var(vars[i], mi.m_sign)) {
mi.m_i = i;
ret.push_back(mi);
}
}
return ret;
}
void get_large_and_small_indices_of_monomimal(const monomial& m,
unsigned_vector & large,
unsigned_vector & _small) {
for (unsigned i = 0; i < m.size(); ++i) {
unsigned j = m.vars()[i];
lp::constraint_index lci = -1, uci = -1;
rational lb, ub;
bool is_strict;
if (m_lar_solver.has_lower_bound(j, lci, lb, is_strict)) {
SASSERT(!is_strict);
if (lb >= rational(1)) {
large.push_back(i);
}
}
if (m_lar_solver.has_upper_bound(j, uci, ub, is_strict)) {
SASSERT(!is_strict);
if (ub <= -rational(1)) {
large.push_back(i);
}
}
if (is_set(lci) && is_set(uci) && -rational(1) <= lb && ub <= rational(1)) {
_small.push_back(i);
}
}
}
// returns true if found
bool find_monomial_of_vars(const svector<lpvar>& vars, monomial& m, rational & sign) const {
auto it = m_rooted_monomials.find(vars);
@ -466,225 +338,6 @@ struct solver::imp {
return true;
}
bool find_complimenting_monomial(const svector<lpvar> & vars, lpvar & j) {
monomial m;
rational other_sign;
if (!find_monomial_of_vars(vars, m, other_sign)) {
return false;
}
j = m.var();
return true;
}
bool find_lpvar_and_sign_with_wrong_val(
const monomial& m,
svector<lpvar> & vars,
const rational& v,
rational sign,
lpvar& j) {
rational other_sign;
monomial mn;
if (!find_monomial_of_vars(vars, mn, other_sign)) {
return false;
}
sign *= other_sign;
j = mn.var();
rational other_val = m_lar_solver.get_column_value_rational(j);
return sign * other_val != v;
}
void add_explanation_of_large_value(lpvar j, expl_set & expl) {
lpci ci;
rational b;
bool strict;
if (m_lar_solver.has_lower_bound(j, ci, b, strict) && rational(1) <= b) {
expl.insert(ci);
} else if (m_lar_solver.has_upper_bound(j, ci, b, strict)) {
SASSERT(b <= rational(-1));
expl.insert(ci);
} else {
UNREACHABLE();
}
}
void add_explanation_of_small_value(lpvar j, expl_set & expl) {
lpci ci;
rational b;
bool strict;
m_lar_solver.has_lower_bound(j, ci, b, strict);
SASSERT(b >= -rational(1));
expl.insert(ci);
m_lar_solver.has_upper_bound(j, ci, b, strict);
SASSERT(b <= rational(1));
expl.insert(ci);
}
void large_lemma_for_proportion_case_on_known_signs(const monomial& m,
unsigned j,
int mon_sign,
int j_sign) {
// Imagine that the signs are all positive and flip them afterwards.
// For this case we would have x[j] < 0 || x[m.var()] < 0 || x[m.var] >= x[j]
// But for the general case we have
// j_sign * x[j] < 0 || mon_sign * x[m.var()] < 0 || mon_sign * x[m.var()] >= j_sign * x[j]
// the first literal
mk_ineq(rational(j_sign), j, lp::lconstraint_kind::LT);
mk_ineq(rational(mon_sign), m.var(), lp::lconstraint_kind::LT);
// the third literal
mk_ineq(rational(mon_sign), m.var(), - rational(j_sign), j, lp::lconstraint_kind::GE);
}
bool large_lemma_for_proportion_case(const monomial& m, const svector<bool> & mask,
const unsigned_vector & large, unsigned j) {
TRACE("nla_solver", );
const rational j_val = m_lar_solver.get_column_value_rational(j);
const rational m_val = m_lar_solver.get_column_value_rational(m.var());
const rational m_abs_val = lp::abs(m_lar_solver.get_column_value_rational(m.var()));
// since the abs of masked factor is greater than or equal to one
// j_val has to be less than or equal to m_abs_val
int j_sign = j_val < - m_abs_val? -1: (j_val > m_abs_val)? 1: 0;
if (j_sign == 0) // abs(j_val) <= abs(m_val) which is not a conflict
return false;
expl_set expl;
add_explanation_of_reducing_to_rooted_monomial(m, expl);
for (unsigned k = 0; k < mask.size(); k++) {
if (mask[k] == 1)
add_explanation_of_large_value(m.vars()[large[k]], expl);
}
m_expl->clear();
m_expl->add(expl);
int mon_sign = m_val < rational(0) ? -1 : 1;
large_lemma_for_proportion_case_on_known_signs(m, j, mon_sign, j_sign);
return true;
}
bool small_lemma_for_proportion_case(const monomial& m, const svector<bool> & mask,
const unsigned_vector & _small, unsigned j) {
TRACE("nla_solver", );
const rational j_val = m_lar_solver.get_column_value_rational(j);
const rational m_val = m_lar_solver.get_column_value_rational(m.var());
const rational m_abs_val = lp::abs(m_lar_solver.get_column_value_rational(m.var()));
// since the abs of the masked factor is less than or equal to one
// j_val has to be greater than or equal to m_abs_val
if (j_val <= - m_abs_val || j_val > m_abs_val)
return false;
expl_set expl;
add_explanation_of_reducing_to_rooted_monomial(m, expl);
for (unsigned k = 0; k < mask.size(); k++) {
if (mask[k] == 1)
add_explanation_of_small_value(m.vars()[_small[k]], expl);
}
m_expl->clear();
m_expl->add(expl);
int mon_sign = m_val < rational(0) ? -1 : 1;
int j_sign = j_val >= rational(0)? 1: -1;
small_lemma_for_proportion_case_on_known_signs(m, j, mon_sign, j_sign);
return true;
}
// It is the case where |x[j]| >= |x[m.var()]| should hold in the model, but it does not.
void small_lemma_for_proportion_case_on_known_signs(const monomial& m, unsigned j, int mon_sign, int j_sign) {
// Imagine that the signs are all positive.
// For this case we would have x[j] < 0 || x[m.var()] < 0 || x[j] >= x[m.var()]
// But for the general case we have
// j_sign * x[j] < 0 || mon_sign * x[m.var()] < 0 || j_sign * x[j] >= mon_sign * x[m.var]
mk_ineq(rational(j_sign), j, lp::lconstraint_kind::LT);
mk_ineq(rational(mon_sign), m.var(), lp::lconstraint_kind::LT);
mk_ineq(rational(j_sign), j, -rational(mon_sign), m.var(), lp::lconstraint_kind::GE);
}
bool large_basic_lemma_for_mon_proportionality(unsigned i_mon, const unsigned_vector& large) {
svector<bool> mask(large.size(), false); // init mask by false
const auto & m = m_monomials[i_mon];
rational sign;
auto vars = reduce_monomial_to_rooted(m.vars(), sign);
auto vars_copy = vars;
auto v = lp::abs(m_lar_solver.get_column_value_rational(m.var()));
// We cross out from vars the "large" variables represented by the mask
for (unsigned k = 0; k < mask.size(); k++) {
if (mask[k]) {
mask[k] = true;
TRACE("nla_solver", tout << "large[" << k << "] = " << large[k];);
SASSERT(std::find(vars.begin(), vars.end(), vars_copy[large[k]]) != vars.end());
vars.erase(vars_copy[large[k]]);
std::sort(vars.begin(), vars.end());
// now the value of vars has to be v*sign
lpvar j;
if (find_complimenting_monomial(vars, j) &&
large_lemma_for_proportion_case(m, mask, large, j)) {
TRACE("nla_solver", print_explanation_and_lemma(tout););
return true;
}
} else {
SASSERT(mask[k]);
mask[k] = false;
vars.push_back(vars_copy[large[k]]); // vars might become unsorted
}
}
return false; // we exhausted the mask and did not find the compliment monomial
}
bool small_basic_lemma_for_mon_proportionality(unsigned i_mon, const unsigned_vector& _small) {
svector<bool> mask(_small.size(), false); // init mask by false
const auto & m = m_monomials[i_mon];
rational sign;
auto vars = reduce_monomial_to_rooted(m.vars(), sign);
auto vars_copy = vars;
auto v = lp::abs(m_lar_solver.get_column_value_rational(m.var()));
// We cross out from vars the "large" variables represented by the mask
for (unsigned k = 0; k < mask.size(); k++) {
if (!mask[k]) {
mask[k] = true;
TRACE("nla_solver", tout << "_small[" << k << "] = " << _small[k];);
SASSERT(std::find(vars.begin(), vars.end(), vars_copy[_small[k]]) != vars.end());
vars.erase(vars_copy[_small[k]]);
std::sort(vars.begin(), vars.end());
// now the value of vars has to be v*sign
lpvar j;
if (find_complimenting_monomial(vars, j) &&
small_lemma_for_proportion_case(m, mask, _small, j)) {
TRACE("nla_solver", print_explanation_and_lemma(tout););
return true;
}
} else {
SASSERT(mask[k]);
mask[k] = false;
vars.push_back(vars_copy[_small[k]]); // vars might become unsorted
}
}
return false; // we exhausted the mask and did not find the compliment monomial
}
// we derive a lemma from |x| >= 1 => |xy| >= |y| or |x| <= 1 => |xy| <= |y|
bool basic_lemma_for_mon_proportionality_from_factors_to_product(unsigned i_mon) {
const monomial & m = m_monomials[i_mon];
unsigned_vector large;
unsigned_vector _small;
get_large_and_small_indices_of_monomimal(m, large, _small);
TRACE("nla_solver", tout << "large size = " << large.size() << ", _small size = " << _small.size(););
if (large.empty() && _small.empty())
return false;
return
large_basic_lemma_for_mon_proportionality(i_mon, large)
||
small_basic_lemma_for_mon_proportionality(i_mon, _small);
}
// Using the following theorems
// |ab| >= |b| iff |a| >= 1 or b = 0
// |ab| <= |b| iff |a| <= 1 or b = 0
// and their commutative variants
bool basic_lemma_for_mon_proportionality(unsigned i_mon) {
TRACE("nla_solver", tout << "basic_lemma_for_mon_proportionality";);
return
basic_lemma_for_mon_proportionality_from_factors_to_product(i_mon) ||
basic_lemma_for_mon_proportionality_from_product_to_factors(i_mon);
}
std::ostream & print_factorization(const factorization& f, std::ostream& out) const {
for (unsigned k = 0; k < f.size(); k++ ) {
print_var(f[k], out);
@ -694,130 +347,6 @@ struct solver::imp {
return out << ", sign = " << f.sign();
}
void restrict_signs_of_xy_and_y_on_lemma(lpvar y, lpvar xy, const rational& _y, const rational& _xy, int& y_sign, int &xy_sign) {
if (_y.is_pos()) {
mk_ineq(y, lp::lconstraint_kind::LE);
y_sign = 1;
} else {
mk_ineq(y, lp::lconstraint_kind::GT);
y_sign = -1;
}
if (_y.is_pos()) {
mk_ineq(xy, lp::lconstraint_kind::LE);
xy_sign = 1;
} else {
mk_ineq(xy, lp::lconstraint_kind::GT);
xy_sign = -1;
}
}
// We derive a lemma from |x| >= 1 || y = 0 => |xy| >= |y|
// Here f is a factorization of monomial xy ( it can have more factors than 2)
// f[k] plays the role of y, the rest of the factors play the role of x
bool lemma_for_proportional_factors_on_vars_ge(lpvar xy, unsigned k, const factorization& f) {
TRACE("nla_solver",
print_factorization(f, tout << "f=");
print_var(f[k], tout << "y="););
NOT_IMPLEMENTED_YET();
/*
const rational & _x = vvr(x);
const rational & _y = vvr(y);
if (!(abs(_x) >= rational(1) || _y.is_zero()))
return false;
// the precondition holds
const rational & _xy = vvr(xy);
if (abs(_xy) >= abs(_y))
return false;
// Here we just create the lemma.
lp::lar_term t;
if (abs(_x) >= rational(1)) {
// add to lemma x < -1 || x > 1
t.add_coeff_var(rational(1), x);
if (_x >= rational(1))
m_lemma->push_back(ineq(lp::lconstraint_kind::LT, t, rational(1)));
else {
lp_assert(_x <= -rational(1));
m_lemma->push_back(ineq(lp::lconstraint_kind::GT, t, -rational(1)));
}
} else {
lp_assert(_y.is_zero() && t.is_empty());
// add to lemma y != 0
t.add_coeff_var(rational(1), y);
m_lemma->push_back(ineq(lp::lconstraint_kind::NE, t, rational::zero()));
}
int xy_sign, y_sign;
restrict_signs_of_xy_and_y_on_lemma(y, xy, _y, _xy, y_sign, xy_sign);
t.clear(); // abs(xy) - abs(y) <= 0
t.add_coeff_var(rational(xy_sign), xy);
t.add_coeff_var(rational(-y_sign), y);
m_lemma->push_back(ineq(lp::lconstraint_kind::GE, t, rational::zero()));
TRACE("nla_solver", tout<< "lemma: ";print_lemma(*m_lemma, tout););
return true;
*/
return false;
}
// we derive a lemma from |x| <= 1 || y = 0 => |xy| <= |y|
bool lemma_for_proportional_factors_on_vars_le(lpvar xy, unsigned k, const factorization & f) {
NOT_IMPLEMENTED_YET();
/*
TRACE("nla_solver",
print_var(xy, tout << "xy=");
print_var(x, tout << "x=");
print_var(y, tout << "y="););
const rational & _x = vvr(x);
const rational & _y = vvr(y);
if (!(abs(_x) <= rational(1) || _y.is_zero()))
return false;
// the precondition holds
const rational & _xy = vvr(xy);
if (abs(_xy) <= abs(_y))
return false;
// Here we just create the lemma.
lp::lar_term t;
if (abs(_x) <= rational(1)) {
// add to lemma x < -1 || x > 1
t.add_coeff_var(rational(1), x);
m_lemma->push_back(ineq(lp::lconstraint_kind::LT, t, -rational(1)));
m_lemma->push_back(ineq(lp::lconstraint_kind::GT, t, rational(1)));
} else {
lp_assert(_y.is_zero() && t.is_empty());
// add to lemma y != 0
t.add_coeff_var(rational(1), y);
m_lemma->push_back(ineq(lp::lconstraint_kind::NE, t, rational::zero()));
}
int y_sign, xy_sign;
restrict_signs_of_xy_and_y_on_lemma(y, xy, _y, _xy, y_sign, xy_sign);
t.clear(); // abs(xy) - abs(y) <= 0
t.add_coeff_var(rational(xy_sign), xy);
t.add_coeff_var(rational(-y_sign), y);
m_lemma->push_back(ineq(lp::lconstraint_kind::LE, t, rational::zero()));
TRACE("nla_solver", tout<< "lemma: ";print_lemma(*m_lemma, tout););
return true;
*/
return false;
}
// we derive a lemma from |x| >= 1 || |y| = 0 => |xy| >= |y|, or the similar of <=
bool lemma_for_proportional_factors(unsigned i_mon, const factorization& f) {
lpvar var_of_mon = m_monomials[i_mon].var();
TRACE("nla_solver", print_var(var_of_mon, tout); tout << " is factorized as "; print_factorization(f, tout););
for (unsigned k = 0; k < f.size(); k++) {
if (lemma_for_proportional_factors_on_vars_ge(var_of_mon, k, f) ||
lemma_for_proportional_factors_on_vars_le(var_of_mon, k, f))
return true;
}
return false;
}
struct factorization_factory_imp: factorization_factory {
const imp& m_imp;
@ -843,27 +372,6 @@ struct solver::imp {
};
// we derive a lemma from |xy| >= |y| => |x| >= 1 || |y| = 0
bool basic_lemma_for_mon_proportionality_from_product_to_factors(unsigned i_mon) {
for (auto factorization : factorization_factory_imp(i_mon, *this)) {
if (factorization.is_empty()) {
TRACE("nla_solver", tout << "empty factorization";);
continue;
}
if (lemma_for_proportional_factors(i_mon, factorization)) {
expl_set exp;
add_explanation_of_reducing_to_rooted_monomial(m_monomials[i_mon], exp);
for (lpvar j : factorization)
add_explanation_of_reducing_to_rooted_monomial(j, exp);
m_expl->clear();
m_expl->add(exp);
return true;
}
}
return false;
}
void explain(const factorization& f, expl_set exp) {
for (lpvar k : f) {
unsigned mon_index = 0;
@ -1032,60 +540,6 @@ struct solver::imp {
mk_ineq(m_monomials[i_mon].var(), -rational(sign), not_one_j,lp::lconstraint_kind::EQ);
return true;
}
// // |xy| >= |y| -> |x| >= 1 or y = 0
// bool basic_lemma_for_mon_proportionality_from_monomial_to_factors_ge_j(unsigned i_mon, const factorization& f, lpvar j) {
// if (vvr(j).is_zero()){
// return false;
// }
// for (lpvar k : f) {
// if (k == j) {
// continue;
// }
// if (vvr(k).is_zero()) {
// mk_
// }
// }
// }
// // |xy| >= |y| -> |x| >= 1 or y = 0
// // or
// // |xy| <= |y| -> |x| <= 1 or y = 0
// bool basic_lemma_for_mon_proportionality_from_monomial_to_factors(unsigned i_mon, const factorization& f) {
// lpvar mon_var = m_monomials[i_mon].var();
// for (lpvar j : f) {
// if (abs(vvr(mon_var)) >= abs(vvr(j))) {
// if (basic_lemma_for_mon_proportionality_from_monomial_to_factors_ge_j(i_mon, f, j))
// return true;
// }
// if (abs(vvr(mon_var)) <= abs(vvr(j)) ) {
// if (basic_lemma_for_mon_proportionality_from_monomial_to_factors_le_j(i_mon, f, j))
// return true;
// }
// }
// return false;
// }
// |x| >= 1 or y = 0 -> |xy| >= |y|
// or
// |x| <= 1 or y = 0 -> |xy| <= |y|
bool basic_lemma_for_mon_proportionality_from_factors_to_monomial(unsigned i_mon, const factorization& f) {
return false;
}
bool basic_lemma_for_mon_proportionality(unsigned i_mon, const factorization& f) {
return false;
// return basic_lemma_for_mon_proportionality_from_monomial_to_factors(i_mon, f)
// ||
// basic_lemma_for_mon_proportionality_from_factors_to_monomial(i_mon, f)
// ;
}
bool basic_lemma_for_mon_neutral(unsigned i_mon, const factorization& factorization) {
return
@ -1100,8 +554,7 @@ struct solver::imp {
bool basic_lemma_for_mon(unsigned i_mon) {
for (auto factorization : factorization_factory_imp(i_mon, *this)) {
if (basic_lemma_for_mon_zero(i_mon, factorization) ||
basic_lemma_for_mon_neutral(i_mon, factorization) ||
basic_lemma_for_mon_proportionality(i_mon, factorization))
basic_lemma_for_mon_neutral(i_mon, factorization))
return true;
}
@ -1739,5 +1192,4 @@ void solver::test_basic_sign_lemma_with_constraints() {
nla.m_imp->print_explanation_and_lemma(std::cout << "expl & lemma: ");
}
}