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revert to a previous state: avoid adding branches for free vars when creating a gomory cut

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Signed-off-by: Lev Nachmanson <levnach@hotmail.com>
This commit is contained in:
Lev Nachmanson 2018-09-13 10:10:29 -07:00
parent 822b0c1d5c
commit 0be5fc5693
5 changed files with 176 additions and 194 deletions
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37
src/util/lp/int_solver.cpp
View file

@ -104,10 +104,11 @@ bool int_solver::is_gomory_cut_target(const row_strip<mpq>& row) {
j = p.var();
if (!is_base(j) && (!at_bound(j) || !is_zero(get_value(j).y))) {
TRACE("gomory_cut", tout << "row is not gomory cut target:\n";
display_column(tout, j););
display_column(tout, j);
tout << "infinitesimal: " << !is_zero(get_value(j).y) << "\n";);
return false;
}
}
}
return true;
}
@ -133,11 +134,22 @@ bool int_solver::current_solution_is_inf_on_cut() const {
}
lia_move int_solver::mk_gomory_cut( unsigned inf_col, const row_strip<mpq> & row) {
lp_assert(column_is_int_inf(inf_col));
gomory gc(m_t, m_k, m_ex, inf_col, row, *this);
return gc.create_cut();
}
int int_solver::find_free_var_in_gomory_row(const row_strip<mpq>& row) {
unsigned j;
for (const auto & p : row) {
j = p.var();
if (!is_base(j) && is_free(j))
return static_cast<int>(j);
}
return -1;
}
lia_move int_solver::proceed_with_gomory_cut(unsigned j) {
const row_strip<mpq>& row = m_lar_solver->get_row(row_of_basic_column(j));
@ -147,7 +159,6 @@ lia_move int_solver::proceed_with_gomory_cut(unsigned j) {
return create_branch_on_column(j);
m_upper = true;
return mk_gomory_cut(j, row);
}
@ -375,17 +386,10 @@ lia_move int_solver::make_hnf_cut() {
#endif
lia_move r = m_hnf_cutter.create_cut(m_t, m_k, m_ex, m_upper, x0);
m_lemma->clear();
m_lemma->push_back(ineq());
ineq & f_in = first_in();
mpq k;
bool upper;
lia_move r = m_hnf_cutter.create_cut(f_in.m_term, k, *m_ex, upper, x0);
if (r == lia_move::cut) {
f_in.m_term.m_v = -k;
f_in.m_cmp = upper? lconstraint_kind::LE : GE;
if (r == lia_move::cut) {
TRACE("hnf_cut",
print_ineq(f_in, tout << "cut:");
m_lar_solver->print_term(*m_t, tout << "cut:");
tout << " <= " << *m_k << std::endl;
for (unsigned i : m_hnf_cutter.constraints_for_explanation()) {
m_lar_solver->print_constraint(i, tout);
}
@ -866,7 +870,7 @@ bool int_solver::at_bound(unsigned j) const {
case column_type::upper_bound:
return mpq_solver.m_upper_bounds[j] == get_value(j);
default:
return true; // a free var is always at a bound
return false;
}
}
@ -1004,18 +1008,19 @@ lia_move int_solver::create_branch_on_column(int j) {
TRACE("check_main_int", tout << "branching" << std::endl;);
lp_assert(m_t.is_empty());
lp_assert(j != -1);
first_in().add_coeff_var(mpq(1), m_lar_solver->adjust_column_index_to_term_index(j));
m_t->add_coeff_var(mpq(1), m_lar_solver->adjust_column_index_to_term_index(j));
if (is_free(j)) {
m_upper = true;
m_k = mpq(0);
} else {
m_upper = left_branch_is_more_narrow_than_right(j);
m_k = m_upper? floor(get_value(j)) : ceil(get_value(j));
m_k = *m_upper? floor(get_value(j)) : ceil(get_value(j));
}
TRACE("int_solver", tout << "branching v" << j << " = " << get_value(j) << "\n";
display_column(tout, j);
tout << "k = " << m_k << std::endl;
);
return lia_move::branch;

34
src/util/lp/int_solver.h
View file

@ -33,39 +33,8 @@ class lar_solver;
template <typename T, typename X>
struct lp_constraint;
struct ineq {
lp::lconstraint_kind m_cmp;
lp::lar_term m_term;
ineq(lp::lconstraint_kind cmp, const lp::lar_term& term) : m_cmp(cmp), m_term(term) {}
ineq() {} // empty constructor
void add_coeff_var(const mpq& c, unsigned j) {
m_term.add_coeff_var(c, j);
}
bool holds(const vector<impq> & x) const {
auto v = m_term.apply(x);
switch(m_cmp) {
case lconstraint_kind::LE: return v <= zero_of_type<impq>();
case lconstraint_kind::LT: return v < zero_of_type<impq>();
case lconstraint_kind::GE: return v >= zero_of_type<impq>();
case lconstraint_kind::GT: return v > zero_of_type<impq>();
case lconstraint_kind::EQ: return v == zero_of_type<impq>();
default:
lp_assert(false);
return false;
}
}
bool is_empty() const { return m_term.is_empty(); }
};
typedef vector<ineq> lemma;
class int_solver {
struct validate_model {
int_solver& s;
lia_move& r;
validate_model(int_solver& s, lia_move& r): s(s), r(r) {}
~validate_model();
};
public:
// fields
lar_solver *m_lar_solver;
@ -85,6 +54,7 @@ public:
mpq const& get_offset() const { return m_k; }
explanation const& get_explanation() const { return m_ex; }
bool is_upper() const { return m_upper; }
lia_move check_wrapper(lar_term& t, mpq& k, explanation& ex);
bool is_base(unsigned j) const;
bool is_real(unsigned j) const;
const impq & lower_bound(unsigned j) const;
@ -146,7 +116,6 @@ private:
unsigned row_of_basic_column(unsigned j) const;
public:
std::ostream & print_ineq(const ineq & in, std::ostream & out) const;
void display_column(std::ostream & out, unsigned j) const;
constraint_index column_upper_bound_constraint(unsigned j) const;
constraint_index column_lower_bound_constraint(unsigned j) const;
@ -171,7 +140,6 @@ public:
int find_inf_int_nbasis_column() const;
lia_move run_gcd_test();
lia_move gomory_cut();
void add_free_vars_ineqs_to_lemma();
lia_move hnf_cut();
lia_move make_hnf_cut();
bool init_terms_for_hnf_cut();

199
src/util/lp/niil_solver.cpp
View file

@ -26,7 +26,7 @@ typedef lp::constraint_index lpci;
typedef std::unordered_set<lpci> expl_set;
typedef nra::mon_eq mon_eq;
typedef lp::var_index lpvar;
typedef lp::ineq ineq;
struct hash_svector {
size_t operator()(const unsigned_vector & v) const {
return svector_hash<unsigned_hash>()(v);
@ -979,117 +979,124 @@ struct solver::imp {
int m_sign; //
};
// struct factors_of_monomial {
// unsigned m_i_mon;
// const imp& m_imp;
// const mon_eq& m_mon;
// unsigned_vector m_minimized_vars;
// int m_sign;
// factors_of_monomial(unsigned i_mon, const imp& s) : m_i_mon(i_mon), m_imp(s),
// m_mon(m_imp.m_monomials[i_mon]) {
// m_minimized_vars = reduce_monomial_to_minimal(i_mon, m_sign);
// }
struct factors_of_monomial {
unsigned m_i_mon;
const imp& m_imp;
const mon_eq& m_mon;
unsigned_vector m_minimized_vars;
int m_sign;
factors_of_monomial(unsigned i_mon, const imp& s) : m_i_mon(i_mon), m_imp(s),
m_mon(m_imp.m_monomials[i_mon]) {
// m_minimized_vars = reduce_monomial_to_minimal(i_mon, m_sign);
}
// struct const_iterator {
// // fields
// unsigned_vector m_mask;
// factors_of_monomial& m_fm;
// //typedefs
struct const_iterator {
// fields
unsigned_vector m_mask;
// factors_of_monomial& m_fm;
//typedefs
// typedef const_iterator self_type;
// typedef signed_two_factorization value_type;
// typedef const signed_two_factorization reference;
// // typedef const column_cell* pointer;
// typedef int difference_type;
// typedef std::forward_iterator_tag iterator_category;
// bool get_factors(unsigned& k, unsigned& j) {
// unsigned_vector a;
// unsigned_vector b;
// for (unsigned j = 0; j < m_mask.size(); j++) {
// if (m_mask[j] == 1) {
// a.push_back(m_fm.m_minimized_vars[j]);
// } else {
// b.push_back(m_fm.m_minimized_vars[j]);
// }
// }
// SASSERT(!a.empty() && !b.empty());
// std::sort(a.begin(), a.end());
// std::sort(b.begin(), b.end());
// int a_sign, b_sign;
// if (a.size() == 1) {
// k = a[0];
// a_sign = 1;
// } else if (!m_imp.find_monomial_of_vars(a, k, a_sign)) {
// return false;
// } else {
// return false;
// }
// if (b.size() == 1) {
// j = b[0];
// b_sign = 1;
// } else if (!m_imp.find_monomial_of_vars(b, j, b_sign)) {
// return false;
// } else {
// return false;
// }
typedef const_iterator self_type;
typedef signed_two_factorization value_type;
typedef const signed_two_factorization reference;
// typedef const column_cell* pointer;
typedef int difference_type;
typedef std::forward_iterator_tag iterator_category;
bool get_factors(unsigned& k, unsigned& j) {
/*
unsigned_vector a;
unsigned_vector b;
for (unsigned j = 0; j < m_mask.size(); j++) {
if (m_mask[j] == 1) {
a.push_back(m_fm.m_minimized_vars[j]);
} else {
b.push_back(m_fm.m_minimized_vars[j]);
}
}
SASSERT(!a.empty() && !b.empty());
std::sort(a.begin(), a.end());
std::sort(b.begin(), b.end());
int a_sign, b_sign;
if (a.size() == 1) {
k = a[0];
a_sign = 1;
} else if (!m_imp.find_monomial_of_vars(a, k, a_sign)) {
return false;
} else {
return false;
}
if (b.size() == 1) {
j = b[0];
b_sign = 1;
} else if (!m_imp.find_monomial_of_vars(b, j, b_sign)) {
return false;
} else {
return false;
}
*/
SASSERT(false); // not implemented
return false;
// }
}
// reference operator*() const {
// unsigned k, j; // the factors
// if (!get_factors(k, j))
// return std::pair<lpvar, lpvar>(static_cast<unsigned>(-1), 0);
// return std::pair<lpvar, lpvar>(k, j);
// }
// void advance_mask() {
// for (unsigned k = 0; k < m_masl.size(); k++) {
// if (mask[k] == 0){
// mask[k] = 1;
// break;
// } else {
// mask[k] = 0;
// }
// }
// }
// self_type operator++() { self_type i = *this; operator++(1); return i; }
// self_type operator++(int) { advance_mask(); return *this; }
reference operator*() const {
SASSERT(false); // not implemented
// unsigned k, j; // the factors
//if (!get_factors(k, j))
// return std::pair<lpvar, lpvar>(static_cast<unsigned>(-1), 0);
return signed_two_factorization();
// return std::pair<lpvar, lpvar>(k, j);
}
void advance_mask() {
SASSERT(false);// not implemented
/*
for (unsigned k = 0; k < m_masl.size(); k++) {
if (mask[k] == 0){
mask[k] = 1;
break;
} else {
mask[k] = 0;
}
}*/
}
self_type operator++() { self_type i = *this; operator++(1); return i; }
self_type operator++(int) { advance_mask(); return *this; }
// const_iterator(const unsigned_vector& mask) :
// m_mask(mask) {
// // SASSERT(false);
// }
// bool operator==(const self_type &other) const {
// return m_mask == other.m_mask;
// }
// bool operator!=(const self_type &other) const { return !(*this == other); }
// };
const_iterator(const unsigned_vector& mask) :
m_mask(mask) {
// SASSERT(false);
}
bool operator==(const self_type &other) const {
return m_mask == other.m_mask;
}
bool operator!=(const self_type &other) const { return !(*this == other); }
};
// const_iterator begin() const {
// unsigned_vector mask(m_mon.m_vs.size(), static_cast<lpvar>(0));
// mask[0] = 1;
// return const_iterator(mask);
// }
const_iterator begin() const {
unsigned_vector mask(m_mon.m_vs.size(), static_cast<lpvar>(0));
mask[0] = 1;
return const_iterator(mask);
}
// const_iterator end() const {
// unsigned_vector mask(m_mon.m_vs.size(), 1);
// return const_iterator(mask);
// }
// };
const_iterator end() const {
unsigned_vector mask(m_mon.m_vs.size(), 1);
return const_iterator(mask);
}
};
bool lemma_for_proportional_factors(unsigned i_mon, lpvar a, lpvar b) {
return false;
}
// we derive a lemma from |xy| > |y| => |x| >= 1 || |y| = 0
bool basic_lemma_for_mon_proportionality_from_product_to_factors(unsigned i_mon) {
SASSERT(false); // not implemented
// for (std::pair<lpvar, lpvar> factors : factors_of_monomial(i_mon, *this))
// if (lemma_for_proportional_factors(i_mon, factors.first, factors.second))
// return true;
for (auto factors : factors_of_monomial(i_mon, *this)) {
// if (lemma_for_proportional_factors(i_mon, factors.first, factors.second))
}
// return true;
SASSERT(false);
return false;
}

10
src/util/lp/niil_solver.h
View file

@ -24,9 +24,15 @@ Revision History:
#include "util/params.h"
#include "nlsat/nlsat_solver.h"
#include "util/lp/lar_solver.h"
#include "util/lp/int_solver.h"
namespace niil {
typedef lp::lemma lemma;
struct ineq {
lp::lconstraint_kind m_cmp;
lp::lar_term m_term;
ineq(lp::lconstraint_kind cmp, const lp::lar_term& term) : m_cmp(cmp), m_term(term) {}
};
typedef vector<ineq> lemma;
// nonlinear integer incremental linear solver
class solver {
struct imp;