mirrors/z3
3
0
Fork 0
mirror of https://github.com/Z3Prover/z3 synced 2025-04-28 19:35:50 +00:00
Code Activity

separate int-cube functionalty

Browse source 
Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2020-02-08 15:27:11 -08:00
parent c12c9a75e6
commit 8d293171d5
5 changed files with 191 additions and 124 deletions
Download patch file Download diff file Expand all files Collapse all files

155
src/math/lp/int_solver.cpp
View file

@ -9,6 +9,7 @@
#include <utility>
#include "math/lp/monic.h"
#include "math/lp/gomory.h"
#include "math/lp/int_cube.h"
namespace lp {
@ -97,12 +98,6 @@ int int_solver::find_inf_int_boxed_base_column_with_smallest_range(unsigned & in
return result;
}
constraint_index int_solver::column_upper_bound_constraint(unsigned j) const {
return m_lar_solver->get_column_upper_bound_witness(j);
}
bool int_solver::current_solution_is_inf_on_cut() const {
const auto & x = m_lar_solver->m_mpq_lar_core_solver.m_r_x;
impq v = m_t.apply(x);
@ -114,15 +109,38 @@ bool int_solver::current_solution_is_inf_on_cut() const {
return v * sign > impq(m_k) * sign;
}
constraint_index int_solver::column_upper_bound_constraint(unsigned j) const {
return m_lar_solver->get_column_upper_bound_witness(j);
}
constraint_index int_solver::column_lower_bound_constraint(unsigned j) const {
return m_lar_solver->get_column_lower_bound_witness(j);
}
unsigned int_solver::row_of_basic_column(unsigned j) const {
return m_lar_solver->row_of_basic_column(j);
}
lp_settings& int_solver::settings() {
return m_lar_solver->settings();
}
const lp_settings& int_solver::settings() const {
return m_lar_solver->settings();
}
bool int_solver::column_is_int(unsigned j) const {
return m_lar_solver->column_is_int(j);
}
bool int_solver::is_real(unsigned j) const {
return !column_is_int(j);
}
bool int_solver::value_is_int(unsigned j) const {
return m_lar_solver->column_value_is_int(j);
}
// this will allow to enable and disable tracking of the pivot rows
struct check_return_helper {
@ -141,102 +159,20 @@ struct check_return_helper {
}
};
impq int_solver::get_cube_delta_for_term(const lar_term& t) const {
if (t.size() == 2) {
bool seen_minus = false;
bool seen_plus = false;
for(const auto & p : t) {
if (!column_is_int(p.var()))
goto usual_delta;
const mpq & c = p.coeff();
if (c == one_of_type<mpq>()) {
seen_plus = true;
} else if (c == -one_of_type<mpq>()) {
seen_minus = true;
} else {
goto usual_delta;
}
}
if (seen_minus && seen_plus)
return zero_of_type<impq>();
return impq(0, 1);
}
usual_delta:
mpq delta = zero_of_type<mpq>();
for (const auto & p : t)
if (column_is_int(p.var()))
delta += abs(p.coeff());
delta *= mpq(1, 2);
return impq(delta);
}
bool int_solver::tighten_term_for_cube(unsigned i) {
unsigned ti = i + m_lar_solver->terms_start_index();
if (!m_lar_solver->term_is_used_as_row(ti))
return true;
const lar_term* t = m_lar_solver->terms()[i];
impq delta = get_cube_delta_for_term(*t);
TRACE("cube", m_lar_solver->print_term_as_indices(*t, tout); tout << ", delta = " << delta;);
if (is_zero(delta))
return true;
return m_lar_solver->tighten_term_bounds_by_delta(i, delta);
}
bool int_solver::tighten_terms_for_cube() {
for (unsigned i = 0; i < m_lar_solver->terms().size(); i++)
if (!tighten_term_for_cube(i)) {
TRACE("cube", tout << "cannot tighten";);
return false;
}
return true;
}
bool int_solver::should_find_cube() {
return m_number_of_calls % settings().m_int_find_cube_period == 0;
}
lia_move int_solver::find_cube() {
if (!should_find_cube())
return lia_move::undef;
settings().stats().m_cube_calls++;
TRACE("cube",
for (unsigned j = 0; j < m_lar_solver->A_r().column_count(); j++)
display_column(tout, j);
tout << m_lar_solver->constraints();
);
m_lar_solver->push();
if (!tighten_terms_for_cube()) {
m_lar_solver->pop();
int_cube ic(*this);
if (should_find_cube()) {
return ic();
}
else {
return lia_move::undef;
}
lp_status st = m_lar_solver->find_feasible_solution();
if (st != lp_status::FEASIBLE && st != lp_status::OPTIMAL) {
TRACE("cube", tout << "cannot find a feasiblie solution";);
m_lar_solver->pop();
m_lar_solver->move_non_basic_columns_to_bounds();
find_feasible_solution();
// it can happen that we found an integer solution here
return !m_lar_solver->r_basis_has_inf_int()? lia_move::sat: lia_move::undef;
}
m_lar_solver->pop();
m_lar_solver->round_to_integer_solution();
m_lar_solver->set_status(lp_status::FEASIBLE);
lp_assert(settings().get_cancel_flag() || is_feasible());
TRACE("cube", tout << "success";);
settings().stats().m_cube_success++;
return lia_move::sat;
}
void int_solver::find_feasible_solution() {
m_lar_solver->find_feasible_solution();
lp_assert(lp_status::OPTIMAL == m_lar_solver->get_status() || lp_status::FEASIBLE == m_lar_solver->get_status());
}
bool int_solver::should_run_gcd_test() {
return settings().m_int_run_gcd_test;
@ -287,14 +223,6 @@ bool int_solver::hnf_cutter_is_full() const {
m_hnf_cutter.vars().size() >= settings().limit_on_columns_for_hnf_cutter;
}
lp_settings& int_solver::settings() {
return m_lar_solver->settings();
}
const lp_settings& int_solver::settings() const {
return m_lar_solver->settings();
}
bool int_solver::hnf_has_var_with_non_integral_value() const {
for (unsigned j : m_hnf_cutter.vars())
if (!get_value(j).is_int())
@ -634,14 +562,6 @@ bool int_solver::ext_gcd_test(const row_strip<mpq> & row,
return true;
}
/*
linear_combination_iterator<mpq> * int_solver::get_column_iterator(unsigned j) {
if (m_lar_solver->use_tableau())
return new iterator_on_column<mpq, impq>(m_lar_solver->A_r().m_columns[j], m_lar_solver->A_r());
return new iterator_on_indexed_vector<mpq>(m_lar_solver->get_column_in_lu_mode(j));
}
*/
int_solver::int_solver(lar_solver* lar_slv) :
m_lar_solver(lar_slv),
@ -674,7 +594,6 @@ bool int_solver::has_upper(unsigned j) const {
}
}
static void set_lower(impq & l, bool & inf_l, impq const & v ) {
if (inf_l || v > l) {
l = v;
@ -682,7 +601,6 @@ static void set_lower(impq & l, bool & inf_l, impq const & v ) {
}
}
static void set_upper(impq & u, bool & inf_u, impq const & v) {
if (inf_u || v < u) {
u = v;
@ -778,17 +696,6 @@ bool int_solver::get_freedom_interval_for_column(unsigned j, bool & inf_l, impq
return (inf_l || inf_u || l <= u);
}
bool int_solver::column_is_int(unsigned j) const {
return m_lar_solver->column_is_int(j);
}
bool int_solver::is_real(unsigned j) const {
return !column_is_int(j);
}
bool int_solver::value_is_int(unsigned j) const {
return m_lar_solver->column_value_is_int(j);
}
bool int_solver::is_feasible() const {
auto & lcs = m_lar_solver->m_mpq_lar_core_solver;
@ -802,7 +709,7 @@ const impq & int_solver::get_value(unsigned j) const {
}
std::ostream& int_solver::display_column(std::ostream & out, unsigned j) const {
m_lar_solver->m_mpq_lar_core_solver.m_r_solver.print_column_info(j, out);
return m_lar_solver->m_mpq_lar_core_solver.m_r_solver.print_column_info(j, out);
return out;
}