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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2025-09-29 16:14:59 -07:00
parent 69a9d9f0b0
commit c3281f08ef
3 changed files with 246 additions and 98 deletions
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18
src/math/lp/lar_constraints.h
View file

@ -40,8 +40,8 @@ inline std::string lconstraint_kind_string(lconstraint_kind t) {
class lar_base_constraint {
lconstraint_kind m_kind;
mpq m_right_side;
bool m_active;
bool m_is_auxiliary;
bool m_active = false;
bool m_is_auxiliary = false;
unsigned m_j;
u_dependency* m_dep;
@ -49,7 +49,7 @@ public:
virtual vector<std::pair<mpq, lpvar>> coeffs() const = 0;
lar_base_constraint(unsigned j, lconstraint_kind kind, u_dependency* dep, const mpq& right_side) :
m_kind(kind), m_right_side(right_side), m_active(false), m_is_auxiliary(false), m_j(j), m_dep(dep) {}
m_kind(kind), m_right_side(right_side), m_j(j), m_dep(dep) {}
virtual ~lar_base_constraint() = default;
lconstraint_kind kind() const { return m_kind; }
@ -66,9 +66,13 @@ public:
virtual unsigned size() const = 0;
virtual mpq get_free_coeff_of_left_side() const { return zero_of_type<mpq>();}
virtual lar_term const &lhs() const = 0;
};
class lar_var_constraint: public lar_base_constraint {
mutable lar_term * m_lhs = nullptr;
public:
lar_var_constraint(unsigned j, lconstraint_kind kind, u_dependency* dep, const mpq& right_side) :
lar_base_constraint(j, kind, dep, right_side) {}
@ -79,6 +83,11 @@ public:
return ret;
}
unsigned size() const override { return 1;}
lar_term const &lhs() const override {
if (!m_lhs)
m_lhs = alloc(lar_term, rational::one(), column());
return *m_lhs;
}
};
@ -90,13 +99,14 @@ public:
vector<std::pair<mpq, lpvar>> coeffs() const override { return m_term->coeffs_as_vector(); }
unsigned size() const override { return m_term->size();}
lar_term const &lhs() const override { return *m_term; }
};
class constraint_set {
region m_region;
column_namer& m_namer;
u_dependency_manager& m_dep_manager;
vector<lar_base_constraint*> m_constraints;
ptr_vector<lar_base_constraint> m_constraints;
stacked_value<unsigned> m_constraint_count;
unsigned_vector m_active;
stacked_value<unsigned> m_active_lim;

296
src/math/lp/nla_stellensatz.cpp
View file

@ -92,9 +92,9 @@ namespace nla {
m_mon2vars.reset();
m_values.reset();
m_resolvents.reset();
m_old_constraints.reset();
m_new_bounds.reset();
m_to_refine.reset();
m_assumptions.reset();
m_monomials_to_refine.reset();
m_false_constraints.reset();
m_factored_constraints.reset();
m_max_monomial_degree = 0;
m_coi.init();
@ -131,7 +131,7 @@ namespace nla {
auto rhs = lo_bound.x;
auto dep = src.get_column_lower_bound_witness(v);
auto ci = dst.add_var_bound(v, k, rhs);
m_ci2dep.setx(ci, dep, nullptr);
m_assumptions.insert(ci, assumptions{dep});
}
if (src.column_has_upper_bound(v)) {
auto hi_bound = src.get_upper_bound(v);
@ -140,7 +140,7 @@ namespace nla {
auto rhs = hi_bound.x;
auto dep = src.get_column_upper_bound_witness(v);
auto ci = dst.add_var_bound(v, k, rhs);
m_ci2dep.setx(ci, dep, nullptr);
m_assumptions.insert(ci, assumptions{dep});
}
}
for (auto const &[v, vars] : m_mon2vars)
@ -163,6 +163,7 @@ namespace nla {
// 2. bounds assumptions are added as assumptions to the lemma.
//
void stellensatz::add_lemma(lp::explanation const& ex1, vector<ineq> const& ineqs) {
TRACE(arith, display(tout));
auto& lra = c().lra_solver();
lp::explanation ex2;
lemma_builder new_lemma(c(), "stellensatz");
@ -184,20 +185,19 @@ namespace nla {
void stellensatz::explain_constraint(lemma_builder& new_lemma, lp::constraint_index ci, lp::explanation& ex) {
if (m_constraints_in_conflict.contains(ci))
return;
m_constraints_in_conflict.insert(ci);
auto dep = m_ci2dep[ci];
m_solver.lra().push_explanation(dep, ex);
lp::constraint_index old_ci;
if (m_old_constraints.find(ci, old_ci))
explain_constraint(new_lemma, old_ci, ex);
if (!m_new_bounds.contains(ci))
m_constraints_in_conflict.insert(ci);
if (!m_assumptions.contains(ci))
return;
auto const &bounds = m_new_bounds[ci];
auto const &bounds = m_assumptions[ci];
for (auto const &b : bounds) {
if (std::holds_alternative<u_dependency *>(b)) {
auto dep = *std::get_if<u_dependency *>(&b);
m_solver.lra().push_explanation(dep, ex);
}
else if (std::holds_alternative<lp::constraint_index>(b)) {
auto c = *std::get_if<lp::constraint_index>(&b);
explain_constraint(new_lemma, c, ex);
}
else {
//
// the inequality was posted as an assumption
@ -268,19 +268,19 @@ namespace nla {
void stellensatz::saturate_signs(lpvar j, rational const& val_j, svector<lpvar> const& vars,
rational const& val_vars) {
if (val_vars == 0 && val_j != 0) {
bound_justifications bounds;
assumptions bounds;
lbool sign = add_bounds(vars, bounds);
VERIFY(sign == l_undef);
add_ineq("signs = 0", bounds, j, lp::lconstraint_kind::EQ, rational(0));
}
else if (val_j <= 0 && 0 < val_vars) {
bound_justifications bounds;
assumptions bounds;
lbool sign = add_bounds(vars, bounds);
VERIFY(sign == l_false);
add_ineq("signs > 0", bounds, j, lp::lconstraint_kind::GT, rational(0));
}
else if (val_j >= 0 && 0 > val_vars) {
bound_justifications bounds;
assumptions bounds;
lbool sign = add_bounds(vars, bounds);
VERIFY(sign == l_true);
add_ineq("signs < 0", bounds, j, lp::lconstraint_kind::LT, rational(0));
@ -294,19 +294,19 @@ namespace nla {
//
void stellensatz::saturate_units(lpvar j, svector<lpvar> const &vars) {
lpvar non_unit = lp::null_lpvar;
bool sign = false;
int sign = 1;
for (auto v : vars) {
if (m_values[v] == 1)
continue;
if (m_values[v] == -1) {
sign = !sign;
sign = -sign;
continue;
}
if (non_unit != lp::null_lpvar)
return;
non_unit = v;
}
bound_justifications bounds;
assumptions bounds;
for (auto v : vars) {
if (m_values[v] == 1 || m_values[v] == -1) {
bound b(v, lp::lconstraint_kind::EQ, m_values[v]);
@ -316,8 +316,12 @@ namespace nla {
// assert j = +/- non_unit
lp::lar_term lhs;
lhs.add_monomial(rational(1), j);
lhs.add_monomial(rational(sign ? 1 : -1), non_unit);
add_ineq("unit mul", bounds, lhs, lp::lconstraint_kind::EQ, rational(0));
if (non_unit != lp::null_lpvar) {
lhs.add_monomial(rational(-sign), non_unit);
add_ineq("unit mul", bounds, lhs, lp::lconstraint_kind::EQ, rational(0));
} else {
add_ineq("unit mul", bounds, lhs, lp::lconstraint_kind::EQ, rational(sign));
}
}
// Monotonicity axioms:
@ -355,7 +359,7 @@ namespace nla {
// x > 1, y > 0 => xy > y
// x > 1, y < 1 => -xy > -y
void stellensatz::saturate_monotonicity(lpvar j, rational const& val_j, lpvar x, int sign_x, lpvar y, int sign_y) {
bound_justifications bounds;
assumptions bounds;
bound b1(x, sign_x < 0 ? lp::lconstraint_kind::LT : lp::lconstraint_kind::GT, rational(sign_x));
bound b2(y, sign_y < 0 ? lp::lconstraint_kind::LT : lp::lconstraint_kind::GT, rational(0));
bounds.push_back(b1);
@ -376,7 +380,7 @@ namespace nla {
return;
}
// it is a square.
bound_justifications bounds;
assumptions bounds;
add_ineq("squares", bounds, j, lp::lconstraint_kind::GE, rational(0));
}
@ -395,7 +399,7 @@ namespace nla {
}
lp::constraint_index stellensatz::add_ineq(char const* rule,
bound_justifications const& bounds,
assumptions const& bounds,
lp::lar_term const& t, lp::lconstraint_kind k,
rational const& rhs) {
SASSERT(!t.coeffs_as_vector().empty());
@ -406,17 +410,15 @@ namespace nla {
display_constraint(tout << rule << ": ", new_ci) << "\n";
if (!bounds.empty()) display(tout << "\t <- ", bounds) << "\n";);
SASSERT(m_values.size() - 1 == ti);
m_new_bounds.insert(new_ci, bounds);
m_ci2dep.setx(new_ci, nullptr, nullptr);
m_assumptions.insert(new_ci, bounds);
init_occurs(new_ci);
return new_ci;
}
lp::constraint_index stellensatz::add_ineq(char const* rule, bound_justifications const& bounds, lpvar j, lp::lconstraint_kind k,
lp::constraint_index stellensatz::add_ineq(char const* rule, assumptions const& bounds, lpvar j, lp::lconstraint_kind k,
rational const& rhs) {
auto new_ci = m_solver.lra().add_var_bound(j, k, rhs);
m_new_bounds.insert(new_ci, bounds);
m_ci2dep.setx(new_ci, nullptr, nullptr);
m_assumptions.insert(new_ci, bounds);
init_occurs(new_ci);
return new_ci;
}
@ -429,8 +431,9 @@ namespace nla {
void stellensatz::init_occurs(lp::constraint_index ci) {
auto const &con = m_solver.lra().constraints()[ci];
for (auto [coeff, v] : con.coeffs()) {
if (m_mon2vars.contains(v)) {
for (auto cv : con.lhs()) {
auto v = cv.j();
if (is_mon_var(v)) {
for (auto w : m_mon2vars[v]) {
if (w >= m_occurs.size())
m_occurs.resize(w + 1);
@ -464,44 +467,159 @@ namespace nla {
return i == a.size();
};
for (unsigned it = 0; it < m_to_refine.size(); ++it) {
auto j = m_to_refine[it];
unsigned initial_false_constraints = m_false_constraints.size();
for (unsigned it = 0; it < m_false_constraints.size(); ++it) {
if (it > 5*initial_false_constraints)
break;
auto ci1 = m_false_constraints[it];
auto const &con = m_solver.lra().constraints()[ci1];
for (auto const &cv1 : con.lhs()) {
auto j = cv1.j();
if (!is_mon_var(j))
continue;
auto vars = m_mon2vars[j];
if (vars.size() > m_max_monomial_degree)
continue;
for (auto v : vars) {
if (v >= m_occurs.size())
continue;
svector<lpvar> _vars;
_vars.push_back(v);
for (unsigned cidx = 0; cidx < m_occurs[v].size(); ++cidx) {
auto ci2 = m_occurs[v][cidx];
for (auto const & cv2 : m_solver.lra().constraints()[ci2].lhs()) {
auto u = cv2.j();
if (u == v && is_resolvable(ci1, cv1.coeff(), ci2, cv2.coeff()))
resolve(j, ci1, saturate_constraint(ci2, j, _vars));
else if (is_mon_var(u) && is_subset(m_mon2vars[u], vars) &&
is_resolvable(ci1, cv1.coeff(), ci2, cv2.coeff()))
resolve(j, ci1, saturate_constraint(ci2, j, m_mon2vars[u]));
}
}
}
}
}
#if 0
for (unsigned it = 0; it < m_monomials_to_refine.size(); ++it) {
auto j = m_monomials_to_refine[it];
auto vars = m_mon2vars[j];
TRACE(arith, tout << "j" << j << " " << vars << "\n");
for (auto v : vars) {
if (v >= m_occurs.size())
continue;
svector<lpvar> _vars;
_vars.push_back(v);
for (unsigned cidx = 0; cidx < m_occurs[v].size(); ++cidx) {
auto ci = m_occurs[v][cidx];
for (unsigned uidx = 0; uidx < m_solver.lra().constraints()[ci].coeffs().size(); ++uidx) {
auto const &[coeff, u] = m_solver.lra().constraints()[ci].coeffs()[uidx];
auto ci = m_occurs[v][cidx];
for (auto const &cv1 : m_solver.lra().constraints()[ci].lhs()) {
auto u = cv1.j();
if (u == v)
saturate_constraint(ci, j, _vars);
else if (m_mon2vars.contains(u) && is_subset(m_mon2vars[u], vars))
else if (is_mon_var(u) && is_subset(m_mon2vars[u], vars))
saturate_constraint(ci, j, m_mon2vars[u]);
}
}
}
}
#endif
IF_VERBOSE(5,
c().lra_solver().display(verbose_stream() << "original\n");
c().display(verbose_stream());
display(verbose_stream() << "saturated\n"));
}
bool stellensatz::is_resolvable(lp::constraint_index ci1, rational const& c1, lp::constraint_index ci2,
rational const& c2) const {
SASSERT(c1 != 0);
SASSERT(c2 != 0);
auto const &con1 = m_solver.lra().constraints()[ci1];
auto const &con2 = m_solver.lra().constraints()[ci2];
auto k1 = con1.kind();
auto k2 = con2.kind();
for (auto const& cv : con1.lhs())
if (is_mon_var(cv.j()) && m_mon2vars[cv.j()].size() > m_max_monomial_degree)
return false;
for (auto const &cv : con2.lhs())
if (is_mon_var(cv.j()) && m_mon2vars[cv.j()].size() > m_max_monomial_degree)
return false;
bool same_sign = (c1.is_pos() == c2.is_pos());
if (k1 == lp::lconstraint_kind::EQ)
return true;
if (k2 == lp::lconstraint_kind::EQ)
return true;
bool is_le1 = (k1 == lp::lconstraint_kind::LE || k1 == lp::lconstraint_kind::LT);
bool is_le2 = (k2 == lp::lconstraint_kind::LE || k2 == lp::lconstraint_kind::LT);
if ((is_le1 == is_le2) && !same_sign)
return true;
if ((is_le1 != is_le2) && same_sign)
return true;
return false;
}
void stellensatz::resolve(lpvar j, lp::constraint_index ci1, lp::constraint_index ci2) {
// resolut of saturate_constraint could swap inequality,
// so the premise of is_resolveable may not hold.
return;
auto const &constraints = m_solver.lra().constraints();
if (!constraints.valid_index(ci1))
return;
if (!constraints.valid_index(ci2))
return;
auto const &con1 = constraints[ci1];
auto const &con2 = constraints[ci2];
auto k1 = con1.kind();
auto k2 = con2.kind();
auto const & lhs1 = con1.lhs();
auto const & lhs2 = con2.lhs();
auto const& c1 = lhs1.get_coeff(j);
auto const& c2 = lhs2.get_coeff(j);
verbose_stream() << "resolve on " << m_mon2vars[j] << " c1: " << c1 << " c2: " << c2 << "\n";
display_constraint(verbose_stream(), ci1) << "\n";
display_constraint(verbose_stream(), ci2) << "\n";
rational mul1, mul2;
bool is_le1 = (k1 == lp::lconstraint_kind::LE || k1 == lp::lconstraint_kind::LT);
bool is_le2 = (k2 == lp::lconstraint_kind::LE || k2 == lp::lconstraint_kind::LT);
bool is_strict = (k1 == lp::lconstraint_kind::LT || k2 == lp::lconstraint_kind::LT);
if (k1 == lp::lconstraint_kind::EQ) {
mul1 = (c1 > 0 ? -1 : 1) * c2;
mul2 = (c1 > 0 ? c1 : -c1);
}
else if (k2 == lp::lconstraint_kind::EQ) {
mul1 = (c2 > 0 ? c2 : -c2);
mul2 = (c2 > 0 ? -1 : 1) * c1;
}
else if (is_le1 == is_le2) {
SASSERT(c1.is_pos() != c2.is_pos());
mul1 = abs(c2);
mul2 = abs(c1);
}
else {
SASSERT(c1.is_pos() == c2.is_pos());
mul1 = abs(c2);
mul2 = -abs(c1);
}
auto lhs = mul1 * lhs1 + mul2 * lhs2;
auto rhs = mul1 * con1.rhs() + mul2 * con2.rhs();
assumptions bounds;
bounds.push_back(ci1);
bounds.push_back(ci2);
auto new_ci = add_ineq("resolve", bounds, lhs, k1, rhs);
insert_monomials_from_constraint(new_ci);
display_constraint(verbose_stream(), new_ci) << "\n";
}
// multiply by remaining vars
void stellensatz::saturate_constraint(lp::constraint_index old_ci, lpvar mi, svector<lpvar> const& xs) {
lp::constraint_index stellensatz::saturate_constraint(lp::constraint_index old_ci, lpvar mi, svector<lpvar> const& xs) {
resolvent r = {old_ci, mi, xs};
if (m_resolvents.contains(r))
return;
return lp::null_ci;
m_resolvents.insert(r);
lp::lar_base_constraint const& con = m_solver.lra().constraints()[old_ci];
auto const& lhs = con.coeffs();
auto const& lhs = con.lhs();
auto const& rhs = con.rhs();
auto k = con.kind();
if (k == lp::lconstraint_kind::NE || k == lp::lconstraint_kind::EQ)
return; // not supported
return lp::null_ci; // not supported
// xs is a proper subset of vars in mi
@ -514,19 +632,19 @@ namespace nla {
SASSERT(!vars.empty());
SASSERT(vars.size() + xs.size() == m_mon2vars[mi].size());
bound_justifications bounds;
assumptions bounds;
// compute bounds constraints and sign of vars
lbool sign = add_bounds(vars, bounds);
lp::lar_term new_lhs;
rational new_rhs(rhs);
for (auto const & [coeff, v] : lhs) {
for (auto const & cv : lhs) {
unsigned old_sz = vars.size();
if (m_mon2vars.contains(v))
vars.append(m_mon2vars[v]);
if (is_mon_var(cv.j()))
vars.append(m_mon2vars[cv.j()]);
else
vars.push_back(v);
vars.push_back(cv.j());
lpvar new_monic_var = add_monomial(vars);
new_lhs.add_monomial(coeff, new_monic_var);
new_lhs.add_monomial(cv.coeff(), new_monic_var);
vars.shrink(old_sz);
}
if (rhs != 0) {
@ -550,12 +668,13 @@ namespace nla {
}
}
bounds.push_back(old_ci);
auto new_ci = add_ineq("superpose", bounds, new_lhs, k, new_rhs);
IF_VERBOSE(4, display_constraint(verbose_stream(), old_ci) << " -> ";
display_constraint(verbose_stream(), new_lhs.coeffs_as_vector(), k, new_rhs) << "\n");
insert_monomials_from_constraint(new_ci);
m_old_constraints.insert(new_ci, old_ci);
m_factored_constraints.insert(new_ci); // don't bother to factor this because it comes from factors already
return new_ci;
}
// call polynomial factorization using the polynomial manager
@ -588,7 +707,7 @@ namespace nla {
auto v = kv.j();
while (v >= m_pm.num_vars())
m_pm.mk_var();
if (m_mon2vars.contains(v)) {
if (is_mon_var(v)) {
auto const &vars = m_mon2vars[v];
ms.push_back(m_pm.mk_monomial(vars.size(), vars.data()));
}
@ -624,6 +743,7 @@ namespace nla {
}
bool stellensatz::saturate_factors(lp::explanation &ex, vector<ineq> &ineqs) {
return true;
auto indices = m_solver.lra().constraints().indices();
return all_of(indices, [&](auto ci) { return saturate_factors(ci, ex, ineqs); });
}
@ -633,12 +753,12 @@ namespace nla {
return true;
m_factored_constraints.insert(ci);
auto const &con = m_solver.lra().constraints()[ci];
if (all_of(con.coeffs(), [&](auto const& cv) { return !m_mon2vars.contains(cv.second); }))
if (all_of(con.lhs(), [&](auto const& cv) { return !is_mon_var(cv.j()); }))
return true;
term_offset t;
// ignore nested terms and nested polynomials..
for (auto const& [coeff, v] : con.coeffs())
t.first.add_monomial(coeff, v);
for (auto const& cv : con.lhs())
t.first.add_monomial(cv.coeff(), cv.j());
t.second = -con.rhs();
vector<std::pair<term_offset, unsigned>> factors;
@ -657,7 +777,7 @@ namespace nla {
bool is_square = all_of(factors, [&](auto const &f) { return f.second % 2 == 0; });
if (is_square) {
auto v = add_term(t);
bound_justifications bounds;
assumptions bounds;
add_ineq("squares", bounds, v, lp::lconstraint_kind::GE, rational(0));
}
@ -691,7 +811,7 @@ namespace nla {
SASSERT(k < factors.size());
auto v = add_term(factors[k].first);
bound_justifications bounds;
assumptions bounds;
bound b(v, lp::lconstraint_kind::EQ, rational(0));
bounds.push_back(b);
add_ineq("factor = 0", bounds, v, lp::lconstraint_kind::EQ, rational(0));
@ -704,7 +824,7 @@ namespace nla {
for (auto & f : factors) {
if (f.second % 2 == 0)
continue;
bound_justifications bounds;
assumptions bounds;
auto v = add_term(f.first);
auto k = m_values[v] > 0 ? lp::lconstraint_kind::GE : lp::lconstraint_kind::LE;
bounds.push_back(bound(v, k, rational(0)));
@ -714,7 +834,9 @@ namespace nla {
}
if ((prod > 0 && k == lp::lconstraint_kind::LE) || (prod < 0 && k == lp::lconstraint_kind::GE)) {
return true;
// this is a conflict with the current evaluation. Produce a lemma that blocks
// TODO, need to check if variables use fresh monomials
ex.push_back(ci);
for (auto &f : factors) {
auto [t, offset] = f.first;
@ -736,7 +858,7 @@ namespace nla {
// add bound assumptions from vars
// return the sign of the product of vars under the current interpretation.
//
lbool stellensatz::add_bounds(svector<lpvar> const& vars, bound_justifications& bounds) {
lbool stellensatz::add_bounds(svector<lpvar> const& vars, assumptions& bounds) {
bool sign = false;
auto &src = c().lra_solver();
auto &dst = m_solver.lra();
@ -827,19 +949,20 @@ namespace nla {
// other approach: use a lex ordering on monomials and insert the lex leading monomial.
// to avoid blowup, only insert monomials up to a certain degree.
void stellensatz::insert_monomials_from_constraint(lp::constraint_index ci) {
if (constraint_is_true(ci))
if (/*false && */ constraint_is_true(ci))
return;
m_false_constraints.insert(ci);
auto const& con = m_solver.lra().constraints()[ci];
for (auto [coeff, v] : con.coeffs())
if (m_mon2vars.contains(v) && m_mon2vars[v].size() <= m_max_monomial_degree)
m_to_refine.insert(v);
for (auto cv : con.lhs())
if (is_mon_var(cv.j()) && m_mon2vars[cv.j()].size() <= m_max_monomial_degree)
m_monomials_to_refine.insert(cv.j());
}
bool stellensatz::constraint_is_true(lp::constraint_index ci) {
bool stellensatz::constraint_is_true(lp::constraint_index ci) const {
auto const& con = m_solver.lra().constraints()[ci];
auto lhs = -con.rhs();
for (auto const& [coeff, v] : con.coeffs())
lhs += coeff * m_values[v];
for (auto const& cv : con.lhs())
lhs += cv.coeff() * m_values[cv.j()];
switch (con.kind()) {
case lp::lconstraint_kind::GT:
return lhs > 0;
@ -867,22 +990,20 @@ namespace nla {
out << "\n";
}
for (auto ci : m_solver.lra().constraints().indices()) {
lp::constraint_index old_ci;
out << "(" << ci << ") ";
display_constraint(out, ci);
if (m_old_constraints.find(ci, old_ci))
out << " [parent (" << old_ci << ")] ";
out << "\n";
if (!m_new_bounds.contains(ci))
bool is_true = constraint_is_true(ci);
out << (is_true ? " [true]" : " [false]") << "\n";
if (!m_assumptions.contains(ci))
continue;
out << "\t<- ";
display(out, m_new_bounds[ci]);
display(out, m_assumptions[ci]);
out << "\n";
}
return out;
}
std::ostream& stellensatz::display(std::ostream& out, bound_justifications const& bounds) const {
std::ostream& stellensatz::display(std::ostream& out, assumptions const& bounds) const {
for (auto b : bounds) {
if (std::holds_alternative<u_dependency *>(b)) {
auto dep = *std::get_if<u_dependency *>(&b);
@ -890,7 +1011,12 @@ namespace nla {
c().lra_solver().dep_manager().linearize(dep, cs);
for (auto c : cs)
out << "[o " << c << "] "; // constraint index from c().lra_solver.
} else {
}
else if (std::holds_alternative<lp::constraint_index>(b)) {
auto ci = *std::get_if<lp::constraint_index>(&b);
out << "(" << ci << ") "; // constraint index from this solver.
}
else {
auto [v, k, rhs] = *std::get_if<bound>(&b);
out << "[j" << v << " " << k << " " << rhs << "] ";
}
@ -915,7 +1041,7 @@ namespace nla {
for (auto [v, coeff] : t.first) {
c().display_coeff(out, first, coeff);
first = false;
if (m_mon2vars.contains(v))
if (is_mon_var(v))
display_product(out, m_mon2vars[v]);
else
out << "j" << v;
@ -927,17 +1053,18 @@ namespace nla {
std::ostream& stellensatz::display_constraint(std::ostream& out, lp::constraint_index ci) const {
auto const& con = m_solver.lra().constraints()[ci];
return display_constraint(out, con.coeffs(), con.kind(), con.rhs());
return display_constraint(out, con.lhs(), con.kind(), con.rhs());
}
std::ostream& stellensatz::display_constraint(std::ostream& out,
vector<std::pair<rational, lpvar>> const& lhs,
lp::lar_term const& lhs,
lp::lconstraint_kind k, rational const& rhs) const {
bool first = true;
for (auto [coeff, v] : lhs) {
c().display_coeff(out, first, coeff);
for (auto cv : lhs) {
auto v = cv.j();
c().display_coeff(out, first, cv.coeff());
first = false;
if (m_mon2vars.contains(v))
if (is_mon_var(v))
display_product(out, m_mon2vars[v]);
else
out << "j" << v;
@ -971,6 +1098,12 @@ namespace nla {
if (update_values())
return l_true;
return l_undef;
// At this point it is not sound to use value assumptions
// because the model changed from the outer LRA solver.
// Also value assumptions made in a previous iteration may no longer be valid.
// this can be fixed by asserting the value assumptions as bounds directly and
// making them depend on themselves.
TRACE(arith, s.display(tout));
if (!s.saturate_factors(ex, ineqs))
return l_false;
@ -1014,7 +1147,7 @@ namespace nla {
auto const &value = values[i];
bool is_int = lra_solver->var_is_int(i);
SASSERT(!is_int || value.is_int());
if (s.m_mon2vars.contains(i))
if (s.is_mon_var(i))
s.m_values[i] = s.value(s.m_mon2vars[i]);
else
s.m_values[i] = value;
@ -1022,18 +1155,19 @@ namespace nla {
auto indices = lra_solver->constraints().indices();
bool satisfies_products = all_of(indices, [&](auto ci) {
return s.constraint_is_true(ci);});
s.m_to_refine.reset();
s.m_monomials_to_refine.reset();
s.m_false_constraints.reset();
// check if all constraints are satisfied
// if they are, then update the model of parent lra solver.
for (auto ci : indices)
s.insert_monomials_from_constraint(ci);
SASSERT(satisfies_products == s.m_to_refine.empty());
SASSERT(satisfies_products == s.m_monomials_to_refine.empty());
if (satisfies_products) {
TRACE(arith, tout << "found satisfying model\n");
for (auto v : s.m_coi.vars())
s.c().lra_solver().set_column_value(v, lp::impq(s.m_values[v], rational(0)));
}
for (auto j : s.m_to_refine) {
for (auto j : s.m_monomials_to_refine) {
auto val_j = values[j];
auto const &vars = s.m_mon2vars[j];
auto val_vars = s.m_values[j];

30
src/math/lp/nla_stellensatz.h
View file

@ -39,14 +39,13 @@ namespace nla {
lp::lconstraint_kind k;
rational rhs;
};
using bound_justification = std::variant<u_dependency*, bound>;
using bound_justifications = vector<bound_justification>;
using assumption = std::variant<u_dependency*, bound, lp::constraint_index>;
using assumptions = vector<assumption>;
coi m_coi;
u_map<bound_justifications> m_new_bounds;
u_map<lp::constraint_index> m_old_constraints;
indexed_uint_set m_to_refine;
ptr_vector<u_dependency> m_ci2dep;
u_map<assumptions> m_assumptions; // map from constraint to set of assumptions
indexed_uint_set m_monomials_to_refine;
indexed_uint_set m_false_constraints; // constraints that are false in the current model
vector<rational> m_values;
struct eq {
bool operator()(unsigned_vector const& a, unsigned_vector const& b) const {
@ -55,6 +54,8 @@ namespace nla {
};
map<unsigned_vector, unsigned, svector_hash<unsigned_hash>, eq> m_vars2mon;
u_map<unsigned_vector> m_mon2vars;
bool is_mon_var(lpvar v) const { return m_mon2vars.contains(v); }
unsigned m_max_monomial_degree = 0;
vector<svector<lp::constraint_index>> m_occurs; // map from variable to constraints they occur.
@ -88,24 +89,27 @@ namespace nla {
void init_occurs();
void init_occurs(lp::constraint_index ci);
bool constraint_is_true(lp::constraint_index ci);
bool constraint_is_true(lp::constraint_index ci) const;
void insert_monomials_from_constraint(lp::constraint_index ci);
// additional variables and monomials and constraints
using term_offset = std::pair<lp::lar_term, rational>; // term and its offset
lpvar add_monomial(svector<lp::lpvar> const& vars);
lpvar add_term(term_offset &t);
lp::constraint_index add_ineq(char const* rule, bound_justifications const& bounds, lp::lar_term const &t, lp::lconstraint_kind k, rational const &rhs);
lp::constraint_index add_ineq(char const* rule, bound_justifications const &bounds, lpvar j, lp::lconstraint_kind k,
lp::constraint_index add_ineq(char const* rule, assumptions const& bounds, lp::lar_term const &t, lp::lconstraint_kind k, rational const &rhs);
lp::constraint_index add_ineq(char const* rule, assumptions const &bounds, lpvar j, lp::lconstraint_kind k,
rational const &rhs);
bool is_int(svector<lp::lpvar> const& vars) const;
rational value(lp::lar_term const &t) const;
rational value(svector<lpvar> const &prod) const;
lpvar add_var(bool is_int);
lbool add_bounds(svector<lpvar> const &vars, bound_justifications &bounds);
lbool add_bounds(svector<lpvar> const &vars, assumptions &bounds);
void saturate_constraints();
void saturate_constraint(lp::constraint_index con_id, lp::lpvar mi, svector<lpvar> const & xs);
lp::constraint_index saturate_constraint(lp::constraint_index con_id, lp::lpvar mi, svector<lpvar> const & xs);
bool is_resolvable(lp::constraint_index ci1, rational const& c1, lp::constraint_index ci2, rational const& c2) const;
void resolve(lpvar j, lp::constraint_index ci1, lp::constraint_index ci2);
void saturate_basic_linearize();
void saturate_basic_linearize(lpvar j, rational const &val_j, svector<lpvar> const &vars,
rational const &val_vars);
@ -132,10 +136,10 @@ namespace nla {
std::ostream& display(std::ostream& out) const;
std::ostream& display_product(std::ostream& out, svector<lpvar> const& vars) const;
std::ostream& display_constraint(std::ostream& out, lp::constraint_index ci) const;
std::ostream& display_constraint(std::ostream& out, vector<std::pair<rational, lpvar>> const& lhs,
std::ostream& display_constraint(std::ostream& out, lp::lar_term const& lhs,
lp::lconstraint_kind k, rational const& rhs) const;
std::ostream& display(std::ostream &out, term_offset const &t) const;
std::ostream& display(std::ostream &out, bound_justifications const &bounds) const;
std::ostream& display(std::ostream &out, assumptions const &bounds) const;
public:
stellensatz(core* core);