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randomise branches in int_solver

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Signed-off-by: Lev Nachmanson <levnach@hotmail.com>
This commit is contained in:
Lev Nachmanson 2020-01-31 14:38:28 -08:00
parent d2fc88d675
commit abb13f8c76
3 changed files with 109 additions and 90 deletions
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48
src/math/lp/gomory.cpp
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@ -21,6 +21,8 @@
#include "math/lp/int_solver.h"
#include "math/lp/lar_solver.h"
#include "math/lp/lp_utils.h"
#define SMALL_CUTS 0
namespace lp {
class gomory::imp {
@ -35,7 +37,11 @@ class gomory::imp {
mpq m_one_minus_f;
mpq m_fj;
mpq m_one_minus_fj;
#if SMALL_CUTS
mpq m_abs_max, m_big_number;
#endif
struct found_big {};
const impq & get_value(unsigned j) const { return m_int_solver.get_value(j); }
bool is_real(unsigned j) const { return m_int_solver.is_real(j); }
bool at_lower(unsigned j) const { return m_int_solver.at_lower(j); }
@ -71,6 +77,9 @@ class gomory::imp {
m_t.add_monomial(new_a, j);
m_lcm_den = lcm(m_lcm_den, denominator(new_a));
TRACE("gomory_cut_detail", tout << "new_a = " << new_a << ", k = " << m_k << ", lcm_den = " << m_lcm_den << "\n";);
#if SMALL_CUTS
if (numerator(new_a) > m_big_number) throw found_big();
#endif
}
void real_case_in_gomory_cut(const mpq & a, unsigned j) {
@ -100,6 +109,9 @@ class gomory::imp {
}
TRACE("gomory_cut_detail_real", tout << a << "*v" << j << " k: " << m_k << "\n";);
m_t.add_monomial(new_a, j);
#if SMALL_CUTS
if (numerator(new_a) > m_big_number) throw found_big();
#endif
}
lia_move report_conflict_from_gomory_cut() {
@ -280,6 +292,14 @@ public:
tout << "1 - m_f: " << 1 - m_f << ", get_value(m_inf_col).x - m_f = " << get_value(m_inf_col).x - m_f << "\n";);
lp_assert(m_f.is_pos() && (get_value(m_inf_col).x - m_f).is_int());
#if SMALL_CUTS
m_abs_max = 0;
for (const auto & p : m_row) {
mpq t = abs(ceil(p.coeff()));
if (t > m_abs_max) m_abs_max = t;
}
m_big_number = m_abs_max; // .expt(2);
#endif
mpq one_min_m_f = 1 - m_f;
for (const auto & p : m_row) {
unsigned j = p.var();
@ -290,20 +310,24 @@ public:
}
// use -p.coeff() to make the format compatible with the format used in: Integrating Simplex with DPLL(T)
if (is_real(j)) {
real_case_in_gomory_cut(- p.coeff(), j);
} else {
if (p.coeff().is_int()) {
// m_fj will be zero and no monomial will be added
continue;
try {
if (is_real(j)) {
real_case_in_gomory_cut(- p.coeff(), j);
}
else if (!p.coeff().is_int()) {
some_int_columns = true;
m_fj = fractional_part(-p.coeff());
m_one_minus_fj = 1 - m_fj;
int_case_in_gomory_cut(j);
}
some_int_columns = true;
m_fj = fractional_part(-p.coeff());
m_one_minus_fj = 1 - m_fj;
int_case_in_gomory_cut(j);
}
catch (found_big) {
m_ex->clear();
m_t.clear();
m_k = 1;
return lia_move::undef;
}
}
if (m_t.is_empty())
return report_conflict_from_gomory_cut();
if (some_int_columns)