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limit explosiion of expressions in Grobner, allow rows containing free vars to Grobner

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Signed-off-by: Lev Nachmanson <levnach@hotmail.com>
This commit is contained in:
Lev Nachmanson 2019-12-15 10:58:03 -10:00
parent fb69139daa
commit 7ddcfcafad
3 changed files with 40 additions and 17 deletions
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41
src/math/lp/nla_grobner.cpp
View file

@ -26,7 +26,8 @@ grobner::grobner(core *c, intervals *s)
: common(c, s),
m_gc(m_nex_creator,
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()
),
m_look_for_fixed_vars_in_rows(false) {
std::function<void (lp::explanation const& e, std::ostream & out)> de;
@ -78,13 +79,12 @@ void grobner::add_var_and_its_factors_to_q_and_collect_new_rows(lpvar j, svector
TRACE("grobner", tout << "j = " << j << ", "; c().print_var(j, tout) << "\n";);
const auto& matrix = c().m_lar_solver.A_r();
c().insert_to_active_var_set(j);
const auto & core_slv = c().m_lar_solver.m_mpq_lar_core_solver;
for (auto & s : matrix.m_columns[j]) {
unsigned row = s.var();
if (m_rows.contains(row)) continue;
if (c().var_is_free(core_slv.m_r_basis[row])) {
TRACE("grobner", tout << "ignore the row " << row << " with the free basic var\n";);
continue; // mimic the behavior of the legacy solver
if (m_rows.contains(row)) continue;
if (matrix.m_rows[row].size() > c().m_nla_settings.grobner_row_length_limit()) {
TRACE("grobner", tout << "ignore the row " << row << " with the size " << matrix.m_rows[row].size() << "\n";);
continue;
}
m_rows.insert(row);
for (auto& rc : matrix.m_rows[row]) {
@ -611,11 +611,16 @@ void grobner_core::superpose(equation * eq1, equation * eq2) {
}
equation* eq = alloc(equation);
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()));
m_stats.m_superposed++;
update_stats_max_degree_and_size(eq);
eq->m_expr = m_nex_creator.simplify(eq->m_expr);
insert_to_simplify(eq);
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()) ||
eq->expr()->size() > m_superposed_exp_size_limit) {
TRACE("grobner", display_equation(tout, *eq) << " is too complex: deleting it\n;";);
del_equation(eq);
} else {
m_stats.m_superposed++;
update_stats_max_degree_and_size(eq);
insert_to_simplify(eq);
}
}
@ -734,8 +739,17 @@ std::ostream& grobner_core::print_stats(std::ostream & out) const {
}
void grobner_core::update_stats_max_degree_and_size(const equation *e) {
m_stats.m_max_expr_size = std::max(m_stats.m_max_expr_size, e->expr()->size());
m_stats.m_max_expr_degree = std::max(m_stats.m_max_expr_degree, e->expr()->get_degree());
if (m_stats.m_max_expr_size < e->expr()->size()) {
TRACE("grobner_stats_d", tout << "expr size = " << e->expr()->size() << "\n";);
TRACE("grobner_stats_d", display_equation(tout, *e););
m_stats.m_max_expr_size = e->expr()->size();
}
auto deg = e->expr()->get_degree();
if (m_stats.m_max_expr_degree < deg) {
TRACE("grobner_stats_d", tout << "expr degree = " << deg << "\n";);
m_stats.m_max_expr_degree = deg;
}
}
void grobner_core::display_equations(std::ostream & out, equation_set const & v, char const * header) const {
@ -767,6 +781,7 @@ void grobner_core::assert_eq_0(nex* e, common::ci_dependency * dep) {
c().print_var(j, tout << "(") << ")\n";
} */);
insert_to_simplify(eq);
update_stats_max_degree_and_size(eq);
}
void grobner_core::init_equation(equation* eq, nex*e, common::ci_dependency * dep) {

8
src/math/lp/nla_grobner.h
View file

@ -89,13 +89,15 @@ private:
bool m_changed_leading_term;
equation_set m_all_eqs;
unsigned m_grobner_eqs_threshold;
unsigned m_superposed_exp_size_limit;
public:
grobner_core(nex_creator& nc, reslimit& lim, unsigned eqs_threshold) :
grobner_core(nex_creator& nc, reslimit& lim, unsigned eqs_threshold, unsigned superposed_expr_size_limit) :
m_nex_creator(nc),
m_limit(lim),
m_dep_manager(m_val_manager, m_alloc),
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)
{}
~grobner_core();
@ -179,7 +181,7 @@ private:
void add_var_and_its_factors_to_q_and_collect_new_rows(lpvar j, svector<lpvar>& q);
void init();
void compute_basis();
std::unordered_set<lpvar> grobner::get_vars_of_expr_with_opening_terms(const nex* e);
std::unordered_set<lpvar> get_vars_of_expr_with_opening_terms(const nex* e);
void display_matrix(std::ostream & out) const;
std::ostream& display(std::ostream& out) const { return m_gc.display(out); }
void add_row(unsigned);

8
src/math/lp/nla_settings.h
View file

@ -31,6 +31,8 @@ class nla_settings {
bool m_run_grobner;
unsigned m_grobner_frequency;
unsigned m_grobner_eqs_threshold;
unsigned m_grobner_row_length_limit;
unsigned m_grobner_superposed_expr_size_limit;
public:
nla_settings() : m_run_order(true),
@ -40,7 +42,9 @@ public:
m_horner_row_length_limit(10),
m_run_grobner(true),
m_grobner_frequency(5),
m_grobner_eqs_threshold(512)
m_grobner_eqs_threshold(512),
m_grobner_row_length_limit(10),
m_grobner_superposed_expr_size_limit(50)
{}
unsigned grobner_eqs_threshold() const { return m_grobner_eqs_threshold; }
@ -65,5 +69,7 @@ public:
unsigned grobner_frequency() const { 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_superposed_expr_size_limit() const { return m_grobner_superposed_expr_size_limit; }
};
}