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z3-z3-4.12.6.src.math.lp.nra_solver.cpp Maven / Gradle / Ivy
/*
Copyright (c) 2017 Microsoft Corporation
Author: Nikolaj Bjorner, Lev Nachmanson
*/
#include "math/lp/lar_solver.h"
#include "math/lp/nra_solver.h"
#include "nlsat/nlsat_solver.h"
#include "math/polynomial/polynomial.h"
#include "math/polynomial/algebraic_numbers.h"
#include "util/map.h"
#include "util/uint_set.h"
#include "math/lp/nla_core.h"
namespace nra {
typedef nla::mon_eq mon_eq;
typedef nla::variable_map_type variable_map_type;
struct solver::imp {
lp::lar_solver& lra;
reslimit& m_limit;
params_ref m_params;
u_map m_lp2nl; // map from lar_solver variables to nlsat::solver variables
indexed_uint_set m_term_set;
scoped_ptr m_nlsat;
scoped_ptr m_values; // values provided by LRA solver
scoped_ptr m_tmp1, m_tmp2;
nla::core& m_nla_core;
imp(lp::lar_solver& s, reslimit& lim, params_ref const& p, nla::core& nla_core):
lra(s),
m_limit(lim),
m_params(p),
m_nla_core(nla_core) {}
bool need_check() {
return m_nla_core.m_to_refine.size() != 0;
}
indexed_uint_set m_mon_set, m_constraint_set;
struct occurs {
unsigned_vector constraints;
unsigned_vector monics;
unsigned_vector terms;
};
void init_cone_of_influence() {
indexed_uint_set visited;
unsigned_vector todo;
vector var2occurs;
m_term_set.reset();
m_mon_set.reset();
m_constraint_set.reset();
for (auto ci : lra.constraints().indices()) {
auto const& c = lra.constraints()[ci];
for (auto const& [coeff, v] : c.coeffs()) {
var2occurs.reserve(v + 1);
var2occurs[v].constraints.push_back(ci);
}
}
for (auto const& m : m_nla_core.emons()) {
for (auto v : m.vars()) {
var2occurs.reserve(v + 1);
var2occurs[v].monics.push_back(m.var());
}
}
for (const auto *t : lra.terms() ) {
for (auto const iv : *t) {
auto v = iv.j();
var2occurs.reserve(v + 1);
var2occurs[v].terms.push_back(t->j());
}
}
for (auto const& m : m_nla_core.m_to_refine)
todo.push_back(m);
for (unsigned i = 0; i < todo.size(); ++i) {
auto v = todo[i];
if (visited.contains(v))
continue;
visited.insert(v);
var2occurs.reserve(v + 1);
for (auto ci : var2occurs[v].constraints) {
m_constraint_set.insert(ci);
auto const& c = lra.constraints()[ci];
for (auto const& [coeff, w] : c.coeffs())
todo.push_back(w);
}
for (auto w : var2occurs[v].monics)
todo.push_back(w);
for (auto ti : var2occurs[v].terms) {
for (auto iv : lra.get_term(ti))
todo.push_back(iv.j());
todo.push_back(ti);
}
if (lra.column_has_term(v)) {
m_term_set.insert(v);
for (auto kv : lra.get_term(v))
todo.push_back(kv.j());
}
if (m_nla_core.is_monic_var(v)) {
m_mon_set.insert(v);
for (auto w : m_nla_core.emons()[v])
todo.push_back(w);
}
}
}
void reset() {
m_values = nullptr;
m_tmp1 = nullptr; m_tmp2 = nullptr;
m_nlsat = alloc(nlsat::solver, m_limit, m_params, false);
m_values = alloc(scoped_anum_vector, am());
m_term_set.reset();
m_lp2nl.reset();
}
/**
\brief one-shot nlsat check.
A one shot checker is the least functionality that can
enable non-linear reasoning.
In addition to checking satisfiability we would also need
to identify equalities in the model that should be assumed
with the remaining solver.
TBD: use partial model from lra_solver to prime the state of nlsat_solver.
TBD: explore more incremental ways of applying nlsat (using assumptions)
*/
lbool check() {
SASSERT(need_check());
reset();
vector core;
init_cone_of_influence();
// add linear inequalities from lra_solver
for (auto ci : m_constraint_set)
add_constraint(ci);
// add polynomial definitions.
for (auto const& m : m_mon_set)
add_monic_eq(m_nla_core.emons()[m]);
// add term definitions.
for (unsigned i : m_term_set)
add_term(i);
TRACE("nra", m_nlsat->display(tout));
lbool r = l_undef;
try {
r = m_nlsat->check();
}
catch (z3_exception&) {
if (m_limit.is_canceled()) {
r = l_undef;
}
else {
throw;
}
}
TRACE("nra",
m_nlsat->display(tout << r << "\n");
display(tout);
for (auto [j, x] : m_lp2nl) tout << "j" << j << " := x" << x << "\n";);
switch (r) {
case l_true:
m_nla_core.set_use_nra_model(true);
lra.init_model();
for (lp::constraint_index ci : lra.constraints().indices())
if (!check_constraint(ci)) {
IF_VERBOSE(0, verbose_stream() << "constraint " << ci << " violated\n";
lra.constraints().display(verbose_stream()));
UNREACHABLE();
return l_undef;
}
for (auto const& m : m_nla_core.emons()) {
if (!check_monic(m)) {
IF_VERBOSE(0, verbose_stream() << "monic " << m << " violated\n";
lra.constraints().display(verbose_stream()));
UNREACHABLE();
return l_undef;
}
}
break;
case l_false: {
lp::explanation ex;
m_nlsat->get_core(core);
for (auto c : core) {
unsigned idx = static_cast(static_cast(c) - this);
ex.push_back(idx);
TRACE("nra", lra.display_constraint(tout << "ex: " << idx << ": ", idx) << "\n";);
}
nla::new_lemma lemma(m_nla_core, __FUNCTION__);
lemma &= ex;
m_nla_core.set_use_nra_model(true);
break;
}
case l_undef:
break;
}
return r;
}
void add_monic_eq_bound(mon_eq const& m) {
if (!lra.column_has_lower_bound(m.var()) &&
!lra.column_has_upper_bound(m.var()))
return;
polynomial::manager& pm = m_nlsat->pm();
svector vars;
for (auto v : m.vars())
vars.push_back(lp2nl(v));
auto v = m.var();
polynomial::monomial_ref m1(pm.mk_monomial(vars.size(), vars.data()), pm);
polynomial::monomial * mls[1] = { m1 };
polynomial::scoped_numeral_vector coeffs(pm.m());
coeffs.push_back(mpz(1));
polynomial::polynomial_ref p(pm.mk_polynomial(1, coeffs.data(), mls), pm);
if (lra.column_has_lower_bound(v))
add_lb_p(lra.get_lower_bound(v), p, lra.get_column_lower_bound_witness(v));
if (lra.column_has_upper_bound(v))
add_ub_p(lra.get_upper_bound(v), p, lra.get_column_upper_bound_witness(v));
}
void add_monic_eq(mon_eq const& m) {
polynomial::manager& pm = m_nlsat->pm();
svector vars;
for (auto v : m.vars())
vars.push_back(lp2nl(v));
polynomial::monomial_ref m1(pm.mk_monomial(vars.size(), vars.data()), pm);
polynomial::monomial_ref m2(pm.mk_monomial(lp2nl(m.var()), 1), pm);
polynomial::monomial * mls[2] = { m1, m2 };
polynomial::scoped_numeral_vector coeffs(pm.m());
coeffs.push_back(mpz(1));
coeffs.push_back(mpz(-1));
polynomial::polynomial_ref p(pm.mk_polynomial(2, coeffs.data(), mls), pm);
polynomial::polynomial* ps[1] = { p };
bool even[1] = { false };
nlsat::literal lit = m_nlsat->mk_ineq_literal(nlsat::atom::kind::EQ, 1, ps, even);
m_nlsat->mk_clause(1, &lit, nullptr);
}
void add_constraint(unsigned idx) {
auto& c = lra.constraints()[idx];
auto& pm = m_nlsat->pm();
auto k = c.kind();
auto rhs = c.rhs();
auto lhs = c.coeffs();
auto sz = lhs.size();
svector vars;
rational den = denominator(rhs);
for (auto [coeff, v] : lhs) {
vars.push_back(lp2nl(v));
den = lcm(den, denominator(coeff));
}
vector coeffs;
for (auto kv : lhs) {
coeffs.push_back(den * kv.first);
}
rhs *= den;
polynomial::polynomial_ref p(pm.mk_linear(sz, coeffs.data(), vars.data(), -rhs), pm);
polynomial::polynomial* ps[1] = { p };
bool is_even[1] = { false };
nlsat::literal lit;
nlsat::assumption a = this + idx;
switch (k) {
case lp::lconstraint_kind::LE:
lit = ~m_nlsat->mk_ineq_literal(nlsat::atom::kind::GT, 1, ps, is_even);
break;
case lp::lconstraint_kind::GE:
lit = ~m_nlsat->mk_ineq_literal(nlsat::atom::kind::LT, 1, ps, is_even);
break;
case lp::lconstraint_kind::LT:
lit = m_nlsat->mk_ineq_literal(nlsat::atom::kind::LT, 1, ps, is_even);
break;
case lp::lconstraint_kind::GT:
lit = m_nlsat->mk_ineq_literal(nlsat::atom::kind::GT, 1, ps, is_even);
break;
case lp::lconstraint_kind::EQ:
lit = m_nlsat->mk_ineq_literal(nlsat::atom::kind::EQ, 1, ps, is_even);
break;
default:
UNREACHABLE(); // unreachable
}
m_nlsat->mk_clause(1, &lit, a);
}
bool check_monic(mon_eq const& m) {
scoped_anum val1(am()), val2(am());
am().set(val1, value(m.var()));
am().set(val2, rational::one().to_mpq());
for (auto v : m.vars())
am().mul(val2, value(v), val2);
return am().eq(val1, val2);
}
bool check_constraint(unsigned idx) {
auto& c = lra.constraints()[idx];
auto k = c.kind();
auto offset = -c.rhs();
auto lhs = c.coeffs();
scoped_anum val(am()), mon(am());
am().set(val, offset.to_mpq());
for (auto [coeff, v] : lhs) {
am().set(mon, coeff.to_mpq());
am().mul(mon, value(v), mon);
am().add(val, mon, val);
}
am().set(mon, rational::zero().to_mpq());
switch (k) {
case lp::lconstraint_kind::LE:
return am().le(val, mon);
case lp::lconstraint_kind::GE:
return am().ge(val, mon);
case lp::lconstraint_kind::LT:
return am().lt(val, mon);
case lp::lconstraint_kind::GT:
return am().gt(val, mon);
case lp::lconstraint_kind::EQ:
return am().eq(val, mon);
default:
UNREACHABLE();
}
return false;
}
lbool check(dd::solver::equation_vector const& eqs) {
reset();
for (auto const& eq : eqs)
add_eq(*eq);
for (auto const& m : m_nla_core.emons())
if (any_of(m.vars(), [&](lp::lpvar v) { return m_lp2nl.contains(v); }))
add_monic_eq_bound(m);
for (unsigned i : m_term_set)
add_term(i);
for (auto const& [v, w] : m_lp2nl) {
if (lra.column_has_lower_bound(v))
add_lb(lra.get_lower_bound(v), w, lra.get_column_lower_bound_witness(v));
if (lra.column_has_upper_bound(v))
add_ub(lra.get_upper_bound(v), w, lra.get_column_upper_bound_witness(v));
}
lbool r = l_undef;
try {
r = m_nlsat->check();
}
catch (z3_exception&) {
if (m_limit.is_canceled()) {
r = l_undef;
}
else {
throw;
}
}
switch (r) {
case l_true:
m_nla_core.set_use_nra_model(true);
lra.init_model();
for (lp::constraint_index ci : lra.constraints().indices())
if (!check_constraint(ci))
return l_undef;
for (auto const& m : m_nla_core.emons())
if (!check_monic(m))
return l_undef;
break;
case l_false: {
lp::explanation ex;
vector core;
m_nlsat->get_core(core);
u_dependency_manager dm;
vector lv;
for (auto c : core)
dm.linearize(static_cast(c), lv);
for (auto ci : lv)
ex.push_back(ci);
nla::new_lemma lemma(m_nla_core, __FUNCTION__);
lemma &= ex;
break;
}
case l_undef:
break;
}
return r;
}
lbool check(vector const& eqs) {
reset();
for (auto const& eq : eqs)
add_eq(eq);
for (auto const& m : m_nla_core.emons())
add_monic_eq(m);
for (auto const& [v, w] : m_lp2nl) {
if (lra.column_has_lower_bound(v))
add_lb(lra.get_lower_bound(v), w);
if (lra.column_has_upper_bound(v))
add_ub(lra.get_upper_bound(v), w);
}
lbool r = l_undef;
try {
r = m_nlsat->check();
}
catch (z3_exception&) {
if (m_limit.is_canceled()) {
r = l_undef;
}
else {
throw;
}
}
if (r == l_true)
return r;
IF_VERBOSE(0, verbose_stream() << "check-nra " << r << "\n";
m_nlsat->display(verbose_stream());
for (auto const& [v, w] : m_lp2nl) {
if (lra.column_has_lower_bound(v))
verbose_stream() << "x" << w << " >= " << lra.get_lower_bound(v) << "\n";
if (lra.column_has_upper_bound(v))
verbose_stream() << "x" << w << " <= " << lra.get_upper_bound(v) << "\n";
});
return r;
}
void add_eq(dd::solver::equation const& eq) {
add_eq(eq.poly(), eq.dep());
}
void add_eq(dd::pdd const& eq, nlsat::assumption a = nullptr) {
dd::pdd normeq = eq;
rational lc(1);
for (auto const& [c, m] : eq)
lc = lcm(denominator(c), lc);
if (lc != 1)
normeq *= lc;
polynomial::manager& pm = m_nlsat->pm();
polynomial::polynomial_ref p(pdd2polynomial(normeq), pm);
bool is_even[1] = {false};
polynomial::polynomial* ps[1] = {p};
nlsat::literal lit = m_nlsat->mk_ineq_literal(nlsat::atom::kind::EQ, 1, ps, is_even);
m_nlsat->mk_clause(1, &lit, a);
}
void add_lb(lp::impq const& b, unsigned w, nlsat::assumption a = nullptr) {
polynomial::manager& pm = m_nlsat->pm();
polynomial::polynomial_ref p(pm.mk_polynomial(w), pm);
add_lb_p(b, p, a);
}
void add_ub(lp::impq const& b, unsigned w, nlsat::assumption a = nullptr) {
polynomial::manager& pm = m_nlsat->pm();
polynomial::polynomial_ref p(pm.mk_polynomial(w), pm);
add_ub_p(b, p, a);
}
void add_lb_p(lp::impq const& b, polynomial::polynomial* p, nlsat::assumption a = nullptr) {
add_bound_p(b.x, p, b.y <= 0, b.y > 0 ? nlsat::atom::kind::GT : nlsat::atom::kind::LT, a);
}
void add_ub_p(lp::impq const& b, polynomial::polynomial* p, nlsat::assumption a = nullptr) {
add_bound_p(b.x, p, b.y >= 0, b.y < 0 ? nlsat::atom::kind::LT : nlsat::atom::kind::GT, a);
}
// w - bound < 0
// w - bound > 0
void add_bound_p(lp::mpq const& bound, polynomial::polynomial* p1, bool neg, nlsat::atom::kind k, nlsat::assumption a = nullptr) {
polynomial::manager& pm = m_nlsat->pm();
polynomial::polynomial_ref p2(pm.mk_const(bound), pm);
polynomial::polynomial_ref p(pm.sub(p1, p2), pm);
polynomial::polynomial* ps[1] = {p};
bool is_even[1] = {false};
nlsat::literal lit = m_nlsat->mk_ineq_literal(k, 1, ps, is_even);
if (neg)
lit.neg();
m_nlsat->mk_clause(1, &lit, a);
}
void add_bound(lp::mpq const& bound, unsigned w, bool neg, nlsat::atom::kind k, nlsat::assumption a = nullptr) {
polynomial::manager& pm = m_nlsat->pm();
polynomial::polynomial_ref p(pm.mk_polynomial(w), pm);
add_bound_p(bound, p, neg, k, a);
}
polynomial::polynomial* pdd2polynomial(dd::pdd const& p) {
polynomial::manager& pm = m_nlsat->pm();
if (p.is_val())
return pm.mk_const(p.val());
polynomial::polynomial_ref lo(pdd2polynomial(p.lo()), pm);
polynomial::polynomial_ref hi(pdd2polynomial(p.hi()), pm);
unsigned w, v = p.var();
if (!m_lp2nl.find(v, w)) {
w = m_nlsat->mk_var(is_int(v));
m_lp2nl.insert(v, w);
}
polynomial::polynomial_ref vp(pm.mk_polynomial(w, 1), pm);
polynomial::polynomial_ref mp(pm.mul(vp, hi), pm);
return pm.add(lo, mp);
}
bool is_int(lp::lpvar v) {
return lra.var_is_int(v);
}
polynomial::var lp2nl(lp::lpvar v) {
polynomial::var r;
if (!m_lp2nl.find(v, r)) {
r = m_nlsat->mk_var(is_int(v));
m_lp2nl.insert(v, r);
if (!m_term_set.contains(v) && lra.column_has_term(v)) {
m_term_set.insert(v);
}
}
return r;
}
//
void add_term(unsigned term_column) {
const lp::lar_term& t = lra.get_term(term_column);
// code that creates a polynomial equality between the linear coefficients and
// variable representing the term.
svector vars;
rational den(1);
for (lp::lar_term::ival kv : t) {
vars.push_back(lp2nl(kv.j()));
den = lcm(den, denominator(kv.coeff()));
}
vars.push_back(lp2nl(term_column));
vector coeffs;
for (auto kv : t) {
coeffs.push_back(den * kv.coeff());
}
coeffs.push_back(-den);
polynomial::manager& pm = m_nlsat->pm();
polynomial::polynomial_ref p(pm.mk_linear(coeffs.size(), coeffs.data(), vars.data(), rational(0)), pm);
polynomial::polynomial* ps[1] = {p};
bool is_even[1] = {false};
nlsat::literal lit = m_nlsat->mk_ineq_literal(nlsat::atom::kind::EQ, 1, ps, is_even);
m_nlsat->mk_clause(1, &lit, nullptr);
}
nlsat::anum const& value(lp::lpvar v) {
polynomial::var pv;
if (m_lp2nl.find(v, pv))
return m_nlsat->value(pv);
else {
for (unsigned w = m_values->size(); w <= v; ++w) {
scoped_anum a(am());
am().set(a, m_nla_core.val(w).to_mpq());
m_values->push_back(a);
}
return (*m_values)[v];
}
}
nlsat::anum_manager& am() {
return m_nlsat->am();
}
scoped_anum& tmp1() {
if (!m_tmp1)
m_tmp1 = alloc(scoped_anum, am());
return *m_tmp1;
}
scoped_anum& tmp2() {
if (!m_tmp2)
m_tmp2 = alloc(scoped_anum, am());
return *m_tmp2;
}
void updt_params(params_ref& p) {
m_params.append(p);
}
std::ostream& display(std::ostream& out) const {
for (auto m : m_nla_core.emons()) {
out << "j" << m.var() << " = ";
for (auto v : m.vars()) {
out << "j" << v << " ";
}
out << "\n";
}
return out;
}
};
solver::solver(lp::lar_solver& s, reslimit& lim, nla::core & nla_core, params_ref const& p) {
m_imp = alloc(imp, s, lim, p, nla_core);
}
solver::~solver() {
dealloc(m_imp);
}
lbool solver::check() {
return m_imp->check();
}
lbool solver::check(vector const& eqs) {
return m_imp->check(eqs);
}
lbool solver::check(dd::solver::equation_vector const& eqs) {
return m_imp->check(eqs);
}
bool solver::need_check() {
return m_imp->need_check();
}
std::ostream& solver::display(std::ostream& out) const {
return m_imp->display(out);
}
nlsat::anum const& solver::value(lp::lpvar v) {
return m_imp->value(v);
}
nlsat::anum_manager& solver::am() {
return m_imp->am();
}
scoped_anum& solver::tmp1() { return m_imp->tmp1(); }
scoped_anum& solver::tmp2() { return m_imp->tmp2(); }
void solver::updt_params(params_ref& p) {
m_imp->updt_params(p);
}
}
