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Merge pull request #6863 from Z3Prover/nl_branches

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split free vars in nla
This commit is contained in:
Lev Nachmanson 2023-08-21 18:19:21 -07:00 • committed by GitHub
commit 4564752c2f
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GPG key ID: 4AEE18F83AFDEB23
8 changed files with 127 additions and 74 deletions
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3
src/math/lp/lp_settings.h
View file

@ -115,6 +115,7 @@ struct statistics {
unsigned m_hnf_cutter_calls;
unsigned m_hnf_cuts;
unsigned m_nla_calls;
unsigned m_nla_bounds;
unsigned m_horner_calls;
unsigned m_horner_conflicts;
unsigned m_cross_nested_forms;
@ -144,7 +145,7 @@ struct statistics {
st.update("arith-grobner-conflicts", m_grobner_conflicts);
st.update("arith-offset-eqs", m_offset_eqs);
st.update("arith-fixed-eqs", m_fixed_eqs);
st.update("arith-nla-bounds", m_nla_bounds);
}
};

62
src/math/lp/nla_core.cpp
View file

@ -809,6 +809,7 @@ void core::print_stats(std::ostream& out) {
void core::clear() {
m_lemma_vec->clear();
m_literal_vec->clear();
}
void core::init_search() {
@ -1501,12 +1502,28 @@ void core::check_bounded_divisions(vector<lemma>& l_vec) {
m_lemma_vec = &l_vec;
m_divisions.check_bounded_divisions();
}
// looking for a free variable inside of a monic to split
void core::add_bounds() {
unsigned r = random(), sz = m_to_refine.size();
for (unsigned k = 0; k < sz; k++) {
lpvar i = m_to_refine[(k + r) % sz];
auto const& m = m_emons[i];
for (lpvar j : m.vars()) {
if (!var_is_free(j)) continue;
// split the free variable (j <= 0, or j > 0), and return
m_literal_vec->push_back(ineq(j, lp::lconstraint_kind::EQ, rational::zero()));
++lp_settings().stats().m_nla_bounds;
return;
}
}
}
lbool core::check(vector<lemma>& l_vec) {
lbool core::check(vector<ineq>& lits, vector<lemma>& l_vec) {
lp_settings().stats().m_nla_calls++;
TRACE("nla_solver", tout << "calls = " << lp_settings().stats().m_nla_calls << "\n";);
lra.get_rid_of_inf_eps();
m_lemma_vec = &l_vec;
m_literal_vec = &lits;
if (!(lra.get_status() == lp::lp_status::OPTIMAL ||
lra.get_status() == lp::lp_status::FEASIBLE)) {
TRACE("nla_solver", tout << "unknown because of the lra.m_status = " << lra.get_status() << "\n";);
@ -1516,43 +1533,47 @@ lbool core::check(vector<lemma>& l_vec) {
init_to_refine();
patch_monomials();
set_use_nra_model(false);
if (m_to_refine.empty()) { return l_true; }
if (m_to_refine.empty())
return l_true;
init_search();
lbool ret = l_undef;
bool run_grobner = need_run_grobner();
bool run_horner = need_run_horner();
bool run_bounded_nlsat = should_run_bounded_nlsat();
bool run_bounds = params().arith_nl_branching();
if (l_vec.empty() && !done())
auto no_effect = [&]() { return !done() && l_vec.empty() && lits.empty(); };
if (no_effect())
m_monomial_bounds();
if (l_vec.empty() && !done() && improve_bounds())
return l_false;
if (l_vec.empty() && !done() && run_horner)
m_horner.horner_lemmas();
{
std::function<void(void)> check1 = [&]() { if (no_effect() && run_horner) m_horner.horner_lemmas(); };
std::function<void(void)> check2 = [&]() { if (no_effect() && run_grobner) m_grobner(); };
std::function<void(void)> check3 = [&]() { if (no_effect() && run_bounds) add_bounds(); };
if (l_vec.empty() && !done() && run_grobner)
m_grobner();
if (l_vec.empty() && !done())
std::pair<unsigned, std::function<void(void)>> checks[] =
{ {1, check1},
{1, check2},
{1, check3} };
check_weighted(3, checks);
if (!l_vec.empty() || !lits.empty())
return l_false;
}
if (no_effect())
m_basics.basic_lemma(true);
if (l_vec.empty() && !done())
if (no_effect())
m_basics.basic_lemma(false);
if (l_vec.empty() && !done())
if (no_effect())
m_divisions.check();
#if 0
if (l_vec.empty() && !done() && !run_horner)
m_horner.horner_lemmas();
if (l_vec.empty() && !done() && !run_grobner)
m_grobner();
#endif
if (!conflict_found() && !done() && run_bounded_nlsat)
ret = bounded_nlsat();
@ -1636,8 +1657,9 @@ bool core::no_lemmas_hold() const {
}
lbool core::test_check(vector<lemma>& l) {
vector<ineq> lits;
lra.set_status(lp::lp_status::OPTIMAL);
return check(l);
return check(lits, l);
}
std::ostream& core::print_terms(std::ostream& out) const {

5
src/math/lp/nla_core.h
View file

@ -85,6 +85,7 @@ class core {
smt_params_helper m_params;
std::function<bool(lpvar)> m_relevant;
vector<lemma> * m_lemma_vec;
vector<ineq> * m_literal_vec = nullptr;
indexed_uint_set m_to_refine;
tangents m_tangents;
basics m_basics;
@ -110,7 +111,7 @@ class core {
monic const* m_patched_monic = nullptr;
void check_weighted(unsigned sz, std::pair<unsigned, std::function<void(void)>>* checks);
void add_bounds();
// try to improve bounds for variables in monomials.
bool improve_bounds();
@ -384,7 +385,7 @@ public:
bool conflict_found() const;
lbool check(vector<lemma>& l_vec);
lbool check(vector<ineq>& ineqs, vector<lemma>& l_vec);
lbool check_power(lpvar r, lpvar x, lpvar y, vector<lemma>& l_vec);
void check_bounded_divisions(vector<lemma>&);

4
src/math/lp/nla_solver.cpp
View file

@ -42,8 +42,8 @@ namespace nla {
bool solver::need_check() { return m_core->has_relevant_monomial(); }
lbool solver::check(vector<lemma>& l) {
return m_core->check(l);
lbool solver::check(vector<ineq>& lits, vector<lemma>& lemmas) {
return m_core->check(lits, lemmas);
}
void solver::push(){

2
src/math/lp/nla_solver.h
View file

@ -36,7 +36,7 @@ namespace nla {
void push();
void pop(unsigned scopes);
bool need_check();
lbool check(vector<lemma>&);
lbool check(vector<ineq>& lits, vector<lemma>&);
lbool check_power(lpvar r, lpvar x, lpvar y, vector<lemma>&);
bool is_monic_var(lpvar) const;
bool influences_nl_var(lpvar) const;

60
src/sat/smt/arith_solver.cpp
View file

@ -1410,30 +1410,43 @@ namespace arith {
m_lemma = l; //todo avoid the copy
m_explanation = l.expl();
literal_vector core;
for (auto const& ineq : m_lemma.ineqs()) {
bool is_lower = true, pos = true, is_eq = false;
switch (ineq.cmp()) {
case lp::LE: is_lower = false; pos = false; break;
case lp::LT: is_lower = true; pos = true; break;
case lp::GE: is_lower = true; pos = false; break;
case lp::GT: is_lower = false; pos = true; break;
case lp::EQ: is_eq = true; pos = false; break;
case lp::NE: is_eq = true; pos = true; break;
default: UNREACHABLE();
}
TRACE("arith", tout << "is_lower: " << is_lower << " pos " << pos << "\n";);
// TBD utility: lp::lar_term term = mk_term(ineq.m_poly);
// then term is used instead of ineq.m_term
sat::literal lit;
if (is_eq)
lit = mk_eq(ineq.term(), ineq.rs());
else
lit = ctx.expr2literal(mk_bound(ineq.term(), ineq.rs(), is_lower));
core.push_back(pos ? lit : ~lit);
}
for (auto const& ineq : m_lemma.ineqs())
core.push_back(mk_ineq_literal(ineq));
set_conflict_or_lemma(hint_type::nla_h, core, false);
}
void solver::assume_literals() {
for (auto const& ineq : m_nla_literals) {
auto lit = mk_ineq_literal(ineq);
ctx.mark_relevant(lit);
s().set_phase(lit);
}
}
sat::literal solver::mk_ineq_literal(nla::ineq const& ineq) {
bool is_lower = true, pos = true, is_eq = false;
switch (ineq.cmp()) {
case lp::LE: is_lower = false; pos = false; break;
case lp::LT: is_lower = true; pos = true; break;
case lp::GE: is_lower = true; pos = false; break;
case lp::GT: is_lower = false; pos = true; break;
case lp::EQ: is_eq = true; pos = false; break;
case lp::NE: is_eq = true; pos = true; break;
default: UNREACHABLE();
}
TRACE("arith", tout << "is_lower: " << is_lower << " pos " << pos << "\n";);
// TBD utility: lp::lar_term term = mk_term(ineq.m_poly);
// then term is used instead of ineq.m_term
sat::literal lit;
if (is_eq)
lit = mk_eq(ineq.term(), ineq.rs());
else
lit = ctx.expr2literal(mk_bound(ineq.term(), ineq.rs(), is_lower));
return pos ? lit : ~lit;
}
lbool solver::check_nla() {
if (!m.inc()) {
TRACE("arith", tout << "canceled\n";);
@ -1446,9 +1459,10 @@ namespace arith {
return l_true;
m_a1 = nullptr; m_a2 = nullptr;
lbool r = m_nla->check(m_nla_lemma_vector);
lbool r = m_nla->check(m_nla_literals, m_nla_lemma_vector);
switch (r) {
case l_false:
case l_false:
assume_literals();
for (const nla::lemma& l : m_nla_lemma_vector)
false_case_of_check_nla(l);
break;

3
src/sat/smt/arith_solver.h
View file

@ -249,6 +249,7 @@ namespace arith {
// lemmas
lp::explanation m_explanation;
vector<nla::lemma> m_nla_lemma_vector;
vector<nla::ineq> m_nla_literals;
literal_vector m_core, m_core2;
vector<rational> m_coeffs;
svector<enode_pair> m_eqs;
@ -463,6 +464,8 @@ namespace arith {
void set_evidence(lp::constraint_index idx);
void assign(literal lit, literal_vector const& core, svector<enode_pair> const& eqs, euf::th_proof_hint const* pma);
void assume_literals();
sat::literal mk_ineq_literal(nla::ineq const& ineq);
void false_case_of_check_nla(const nla::lemma& l);
void dbg_finalize_model(model& mdl);

62
src/smt/theory_lra.cpp
View file

@ -1979,44 +1979,55 @@ public:
}
nla::lemma m_lemma;
literal mk_literal(nla::ineq const& ineq) {
bool is_lower = true, pos = true, is_eq = false;
switch (ineq.cmp()) {
case lp::LE: is_lower = false; pos = false; break;
case lp::LT: is_lower = true; pos = true; break;
case lp::GE: is_lower = true; pos = false; break;
case lp::GT: is_lower = false; pos = true; break;
case lp::EQ: is_eq = true; pos = false; break;
case lp::NE: is_eq = true; pos = true; break;
default: UNREACHABLE();
}
TRACE("arith", tout << "is_lower: " << is_lower << " pos " << pos << "\n";);
app_ref atom(m);
// TBD utility: lp::lar_term term = mk_term(ineq.m_poly);
// then term is used instead of ineq.m_term
if (is_eq)
atom = mk_eq(ineq.term(), ineq.rs());
else
// create term >= 0 (or term <= 0)
atom = mk_bound(ineq.term(), ineq.rs(), is_lower);
return literal(ctx().get_bool_var(atom), pos);
}
void false_case_of_check_nla(const nla::lemma & l) {
m_lemma = l; //todo avoid the copy
m_explanation = l.expl();
literal_vector core;
for (auto const& ineq : m_lemma.ineqs()) {
bool is_lower = true, pos = true, is_eq = false;
switch (ineq.cmp()) {
case lp::LE: is_lower = false; pos = false; break;
case lp::LT: is_lower = true; pos = true; break;
case lp::GE: is_lower = true; pos = false; break;
case lp::GT: is_lower = false; pos = true; break;
case lp::EQ: is_eq = true; pos = false; break;
case lp::NE: is_eq = true; pos = true; break;
default: UNREACHABLE();
}
TRACE("arith", tout << "is_lower: " << is_lower << " pos " << pos << "\n";);
app_ref atom(m);
// TBD utility: lp::lar_term term = mk_term(ineq.m_poly);
// then term is used instead of ineq.m_term
if (is_eq) {
atom = mk_eq(ineq.term(), ineq.rs());
}
else {
// create term >= 0 (or term <= 0)
atom = mk_bound(ineq.term(), ineq.rs(), is_lower);
}
literal lit(ctx().get_bool_var(atom), pos);
auto lit = mk_literal(ineq);
core.push_back(~lit);
}
set_conflict_or_lemma(core, false);
}
void assume_literal(nla::ineq const& i) {
auto lit = mk_literal(i);
ctx().mark_as_relevant(lit);
ctx().set_true_first_flag(lit.var());
}
final_check_status check_nla_continue() {
m_a1 = nullptr; m_a2 = nullptr;
lbool r = m_nla->check(m_nla_lemma_vector);
lbool r = m_nla->check(m_nla_literals, m_nla_lemma_vector);
switch (r) {
case l_false:
case l_false:
for (const nla::ineq& i : m_nla_literals)
assume_literal(i);
for (const nla::lemma & l : m_nla_lemma_vector)
false_case_of_check_nla(l);
return FC_CONTINUE;
@ -3173,6 +3184,7 @@ public:
lp::explanation m_explanation;
vector<nla::lemma> m_nla_lemma_vector;
vector<nla::ineq> m_nla_literals;
literal_vector m_core;
svector<enode_pair> m_eqs;
vector<parameter> m_params;