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limit the size of expressions in Grobner

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Signed-off-by: Lev Nachmanson <levnach@hotmail.com>
This commit is contained in:
Lev Nachmanson 2019-12-16 11:24:14 -10:00
parent 7ddcfcafad
commit 26956cafb0
3 changed files with 29 additions and 20 deletions
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27
src/math/lp/nla_grobner.cpp
View file

@ -27,7 +27,7 @@ grobner::grobner(core *c, intervals *s)
m_gc(m_nex_creator, m_gc(m_nex_creator,
c->m_reslim, c->m_reslim,
c->m_nla_settings.grobner_eqs_threshold(), c->m_nla_settings.grobner_eqs_threshold(),
c->m_nla_settings.grobner_superposed_expr_size_limit() c->m_nla_settings.grobner_expr_size_limit()
), ),
m_look_for_fixed_vars_in_rows(false) { m_look_for_fixed_vars_in_rows(false) {
std::function<void (lp::explanation const& e, std::ostream & out)> de; std::function<void (lp::explanation const& e, std::ostream & out)> de;
@ -205,13 +205,20 @@ bool grobner_core::compute_basis_step() {
} }
m_stats.m_compute_steps++; m_stats.m_compute_steps++;
simplify_using_to_superpose(*eq); simplify_using_to_superpose(*eq);
if (equation_is_too_complex(eq))
return false;
if (!canceled() && simplify_to_superpose_with_eq(eq)) { if (!canceled() && simplify_to_superpose_with_eq(eq)) {
TRACE("grobner", tout << "eq = "; display_equation(tout, *eq);); TRACE("grobner", tout << "eq = "; display_equation(tout, *eq););
superpose(eq); superpose(eq);
if (equation_is_too_complex(eq)) {
TRACE("grobner", display_equation(tout, *eq) << " is too complex: deleting it\n;";);
del_equation(eq);
} else {
insert_to_superpose(eq); insert_to_superpose(eq);
simplify_m_to_simplify(eq); simplify_m_to_simplify(eq);
TRACE("grobner", tout << "end of iteration:\n"; display(tout);); TRACE("grobner", tout << "end of iteration:\n"; display(tout););
} }
}
return false; return false;
} }
@ -486,7 +493,9 @@ void grobner_core::simplify_target_monomials_sum_j(equation const& source, equat
bool grobner_core::simplify_source_target(equation const& source, equation& target) { bool grobner_core::simplify_source_target(equation const& source, equation& target) {
TRACE("grobner", tout << "simplifying: "; display_equation(tout, target); tout << "\nusing: "; display_equation(tout, source);); TRACE("grobner", tout << "simplifying: "; display_equation(tout, target); tout << "\nusing: "; display_equation(tout, source););
TRACE("grobner_d", tout << "simplifying: " << *(target.expr()) << " using " << *(source.expr()) << "\n";); TRACE("grobner_d", tout << "simplifying: " << *(target.expr()) << " using " << *(source.expr()) << "\n";);
SASSERT(m_nex_creator.is_simplified(*source.expr())); SASSERT(m_nex_creator.is_simplified(*source.expr()) && !equation_is_too_complex(&source));
if (equation_is_too_complex(&target))
return false;
SASSERT(m_nex_creator.is_simplified(*target.expr())); SASSERT(m_nex_creator.is_simplified(*target.expr()));
if (target.expr()->is_scalar()) { if (target.expr()->is_scalar()) {
TRACE("grobner_d", tout << "no simplification\n";); TRACE("grobner_d", tout << "no simplification\n";);
@ -514,7 +523,7 @@ bool grobner_core::simplify_source_target(equation const& source, equation& targ
} }
void grobner_core::process_simplified_target(equation* target, ptr_buffer<equation>& to_remove) { void grobner_core::process_simplified_target(equation* target, ptr_buffer<equation>& to_remove) {
if (is_trivial(target)) { if (is_trivial(target) || equation_is_too_complex(target)) {
to_remove.push_back(target); to_remove.push_back(target);
} else if (m_changed_leading_term) { } else if (m_changed_leading_term) {
insert_to_simplify(target); insert_to_simplify(target);
@ -525,8 +534,7 @@ void grobner_core::process_simplified_target(equation* target, ptr_buffer<equati
bool grobner_core::simplify_to_superpose_with_eq(equation* eq) { bool grobner_core::simplify_to_superpose_with_eq(equation* eq) {
TRACE("grobner_d", tout << "eq->exp " << *(eq->expr()) << "\n";); TRACE("grobner_d", tout << "eq->exp " << *(eq->expr()) << "\n";);
SASSERT(!equation_is_too_complex(eq));
ptr_buffer<equation> to_insert;
ptr_buffer<equation> to_remove; ptr_buffer<equation> to_remove;
ptr_buffer<equation> to_delete; ptr_buffer<equation> to_delete;
for (equation * target : m_to_superpose) { for (equation * target : m_to_superpose) {
@ -537,15 +545,14 @@ bool grobner_core::simplify_to_superpose_with_eq(equation* eq) {
if (simplify_source_target(*eq, *target)) { if (simplify_source_target(*eq, *target)) {
process_simplified_target(target, to_remove); process_simplified_target(target, to_remove);
} }
if (is_trivial(target)) { if (is_trivial(target)||equation_is_too_complex(target)) {
to_delete.push_back(target); to_delete.push_back(target);
} }
else { else {
SASSERT(m_nex_creator.is_simplified(*target->expr())); SASSERT(m_nex_creator.is_simplified(*target->expr()));
} }
} }
for (equation* eq : to_insert)
insert_to_superpose(eq);
for (equation* eq : to_remove) for (equation* eq : to_remove)
m_to_superpose.erase(eq); m_to_superpose.erase(eq);
for (equation* eq : to_delete) for (equation* eq : to_delete)
@ -560,7 +567,7 @@ void grobner_core::simplify_m_to_simplify(equation* eq) {
TRACE("grobner_d", tout << "eq->exp " << *(eq->expr()) << "\n";); TRACE("grobner_d", tout << "eq->exp " << *(eq->expr()) << "\n";);
ptr_buffer<equation> to_delete; ptr_buffer<equation> to_delete;
for (equation* target : m_to_simplify) { for (equation* target : m_to_simplify) {
if (simplify_source_target(*eq, *target) && is_trivial(target)) if (simplify_source_target(*eq, *target) && (is_trivial(target) || equation_is_too_complex(target)))
to_delete.push_back(target); to_delete.push_back(target);
} }
for (equation* eq : to_delete) for (equation* eq : to_delete)
@ -613,7 +620,7 @@ void grobner_core::superpose(equation * eq1, equation * eq2) {
TRACE("grobner_d", tout << "eq1="; display_equation(tout, *eq1) << "eq2="; display_equation(tout, *eq2);); TRACE("grobner_d", tout << "eq1="; display_equation(tout, *eq1) << "eq2="; display_equation(tout, *eq2););
init_equation(eq, expr_superpose(eq1->expr(), eq2->expr(), ab, ac, b, c), m_dep_manager.mk_join(eq1->dep(), eq2->dep())); init_equation(eq, expr_superpose(eq1->expr(), eq2->expr(), ab, ac, b, c), m_dep_manager.mk_join(eq1->dep(), eq2->dep()));
if (m_nex_creator.gt(eq->expr(), eq1->expr()) || m_nex_creator.gt(eq->expr(), eq2->expr()) || if (m_nex_creator.gt(eq->expr(), eq1->expr()) || m_nex_creator.gt(eq->expr(), eq2->expr()) ||
eq->expr()->size() > m_superposed_exp_size_limit) { equation_is_too_complex(eq)) {
TRACE("grobner", display_equation(tout, *eq) << " is too complex: deleting it\n;";); TRACE("grobner", display_equation(tout, *eq) << " is too complex: deleting it\n;";);
del_equation(eq); del_equation(eq);
} else { } else {

10
src/math/lp/nla_grobner.h
View file

@ -89,15 +89,15 @@ private:
bool m_changed_leading_term; bool m_changed_leading_term;
equation_set m_all_eqs; equation_set m_all_eqs;
unsigned m_grobner_eqs_threshold; unsigned m_grobner_eqs_threshold;
unsigned m_superposed_exp_size_limit; unsigned m_expr_size_limit;
public: public:
grobner_core(nex_creator& nc, reslimit& lim, unsigned eqs_threshold, unsigned superposed_expr_size_limit) : grobner_core(nex_creator& nc, reslimit& lim, unsigned eqs_threshold, unsigned expr_size_limit) :
m_nex_creator(nc), m_nex_creator(nc),
m_limit(lim), m_limit(lim),
m_dep_manager(m_val_manager, m_alloc), m_dep_manager(m_val_manager, m_alloc),
m_changed_leading_term(false), m_changed_leading_term(false),
m_grobner_eqs_threshold(eqs_threshold), m_grobner_eqs_threshold(eqs_threshold),
m_superposed_exp_size_limit(superposed_expr_size_limit) m_expr_size_limit(expr_size_limit)
{} {}
~grobner_core(); ~grobner_core();
@ -159,7 +159,9 @@ private:
std::ostream& print_stats(std::ostream&) const; std::ostream& print_stats(std::ostream&) const;
std::ostream& display_dependency(std::ostream& out, common::ci_dependency*) const; std::ostream& display_dependency(std::ostream& out, common::ci_dependency*) const;
bool equation_is_too_complex(const equation* eq) const {
return eq->expr()->size() > m_expr_size_limit;
}
#ifdef Z3DEBUG #ifdef Z3DEBUG
bool test_find_b_c(const nex* ab, const nex* ac, const nex_mul* b, const nex_mul* c); bool test_find_b_c(const nex* ab, const nex* ac, const nex_mul* b, const nex_mul* c);
bool test_find_b(const nex* ab, const nex_mul* b); bool test_find_b(const nex* ab, const nex_mul* b);

6
src/math/lp/nla_settings.h
View file

@ -32,7 +32,7 @@ class nla_settings {
unsigned m_grobner_frequency; unsigned m_grobner_frequency;
unsigned m_grobner_eqs_threshold; unsigned m_grobner_eqs_threshold;
unsigned m_grobner_row_length_limit; unsigned m_grobner_row_length_limit;
unsigned m_grobner_superposed_expr_size_limit; unsigned m_grobner_expr_size_limit;
public: public:
nla_settings() : m_run_order(true), nla_settings() : m_run_order(true),
@ -44,7 +44,7 @@ public:
m_grobner_frequency(5), m_grobner_frequency(5),
m_grobner_eqs_threshold(512), m_grobner_eqs_threshold(512),
m_grobner_row_length_limit(10), m_grobner_row_length_limit(10),
m_grobner_superposed_expr_size_limit(50) m_grobner_expr_size_limit(50)
{} {}
unsigned grobner_eqs_threshold() const { return m_grobner_eqs_threshold; } unsigned grobner_eqs_threshold() const { return m_grobner_eqs_threshold; }
@ -70,6 +70,6 @@ public:
unsigned grobner_frequency() const { return m_grobner_frequency; } unsigned grobner_frequency() const { return m_grobner_frequency; }
unsigned& grobner_frequency() { return m_grobner_frequency; } unsigned& grobner_frequency() { return m_grobner_frequency; }
unsigned grobner_row_length_limit() const { return m_grobner_row_length_limit; } unsigned grobner_row_length_limit() const { return m_grobner_row_length_limit; }
unsigned grobner_superposed_expr_size_limit() const { return m_grobner_superposed_expr_size_limit; } unsigned grobner_expr_size_limit() const { return m_grobner_expr_size_limit; }
}; };
} }