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working on hitting sets

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2014-06-08 14:12:54 +01:00
commit 960e8ea1d5
38 changed files with 1130 additions and 203 deletions
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5
src/math/simplex/simplex.h
View file

@ -174,10 +174,11 @@ namespace simplex {
var_t select_pivot_core(var_t x_i, bool is_below, scoped_numeral& out_a_ij);
int get_num_non_free_dep_vars(var_t x_j, int best_so_far);
var_t pick_var_to_leave(var_t x_j, bool inc, scoped_eps_numeral& gain, scoped_numeral& new_a_ij);
var_t pick_var_to_leave(var_t x_j, bool is_pos,
scoped_eps_numeral& gain, scoped_numeral& new_a_ij, bool& inc);
void select_pivot_primal(var_t v, var_t& x_i, var_t& x_j, scoped_numeral& a_ij, bool& inc);
void select_pivot_primal(var_t v, var_t& x_i, var_t& x_j, scoped_numeral& a_ij, bool& inc_x_i, bool& inc_x_j);
bool at_lower(var_t v) const;

70
src/math/simplex/simplex_def.h
View file

@ -646,13 +646,13 @@ namespace simplex {
scoped_eps_numeral delta(em);
scoped_numeral a_ij(m);
var_t x_i, x_j;
bool inc;
bool inc_x_i, inc_x_j;
while (true) {
if (m_cancel) {
return l_undef;
}
select_pivot_primal(v, x_i, x_j, a_ij, inc);
select_pivot_primal(v, x_i, x_j, a_ij, inc_x_i, inc_x_j);
if (x_j == null_var) {
// optimal
return l_true;
@ -660,12 +660,12 @@ namespace simplex {
TRACE("simplex", tout << "x_i: v" << x_i << " x_j: v" << x_j << "\n";);
var_info& vj = m_vars[x_j];
if (x_i == null_var) {
if (inc && vj.m_upper_valid) {
if (inc_x_j && vj.m_upper_valid) {
delta = vj.m_upper;
delta -= vj.m_value;
update_value(x_j, delta);
}
else if (!inc && vj.m_lower_valid) {
else if (!inc_x_j && vj.m_lower_valid) {
delta = vj.m_lower;
delta -= vj.m_value;
update_value(x_j, delta);
@ -686,7 +686,7 @@ namespace simplex {
pivot(x_i, x_j, a_ij);
TRACE("simplex", display(tout << "after pivot\n"););
move_to_bound(x_i, !inc);
move_to_bound(x_i, !inc_x_i);
SASSERT(well_formed_row(row(m_vars[x_j].m_base2row)));
TRACE("simplex", display(tout););
SASSERT(is_feasible());
@ -705,7 +705,7 @@ namespace simplex {
em.sub(vi.m_upper, vi.m_value, delta);
}
TRACE("simplex", tout << "move " << (to_lower?"to_lower":"to_upper")
<< " v" << x << " " << em.to_string(delta) << "\n";);
<< " v" << x << " delta: " << em.to_string(delta) << "\n";);
col_iterator it = M.col_begin(x), end = M.col_end(x);
for (; it != end && is_pos(delta); ++it) {
//
@ -756,10 +756,11 @@ namespace simplex {
x_i - base variable of row(x_i) to become non-base
x_j - variable in row(v) to make a base variable
a_ij - coefficient to x_j in row(x_i)
inc - whether to increment x_j (true if coefficient in row(v) is negative).
inc - whether to increment x_i
*/
template<typename Ext>
void simplex<Ext>::select_pivot_primal(var_t v, var_t& x_i, var_t& x_j, scoped_numeral& a_ij, bool& inc) {
void simplex<Ext>::select_pivot_primal(var_t v, var_t& x_i, var_t& x_j, scoped_numeral& a_ij,
bool& inc_x_i, bool& inc_x_j) {
row r(m_vars[v].m_base2row);
row_iterator it = M.row_begin(r), end = M.row_end(r);
@ -767,25 +768,27 @@ namespace simplex {
scoped_numeral new_a_ij(m);
x_i = null_var;
x_j = null_var;
inc = false;
inc_x_i = false;
bool inc_y = false;
for (; it != end; ++it) {
var_t x = it->m_var;
if (x == v) continue;
bool is_pos = m.is_pos(it->m_coeff) == m.is_pos(m_vars[v].m_base_coeff);
if ((is_pos && at_upper(x)) || (!is_pos && at_lower(x))) {
TRACE("simplex", tout << "v" << x << " pos: " << is_pos
bool inc_x = m.is_pos(it->m_coeff) == m.is_pos(m_vars[v].m_base_coeff);
if ((inc_x && at_upper(x)) || (!inc_x && at_lower(x))) {
TRACE("simplex", tout << "v" << x << " pos: " << inc_x
<< " at upper: " << at_upper(x)
<< " at lower: " << at_lower(x) << "\n";);
continue; // variable cannot be used for improving bounds.
// TBD check?
}
var_t y = pick_var_to_leave(x, is_pos, new_gain, new_a_ij);
}
var_t y = pick_var_to_leave(x, inc_x, new_gain, new_a_ij, inc_y);
if (y == null_var) {
// unbounded.
x_i = y;
x_j = x;
inc = is_pos;
inc_x_i = inc_y;
inc_x_j = inc_x;
a_ij = new_a_ij;
break;
}
@ -794,20 +797,39 @@ namespace simplex {
((is_zero(new_gain) && is_zero(gain) && (x_i == null_var || y < x_i)));
if (better) {
TRACE("simplex",
em.display(tout << "gain:", gain);
em.display(tout << " new gain:", new_gain);
tout << " base x_i: " << y << ", new base x_j: " << x << ", inc x_j: " << inc_x << "\n";);
x_i = y;
x_j = x;
inc = is_pos;
inc_x_i = inc_y;
inc_x_j = inc_x;
gain = new_gain;
a_ij = new_a_ij;
}
}
}
//
// y is a base variable.
// v is a base variable.
// v*a_v + x*a_x + E = 0
// y*b_y + x*b_x + F = 0
// inc(x) := sign(a_v) == sign(a_x)
// sign_eq := sign(b_y) == sign(b_x)
// sign_eq => (inc(x) != inc(y))
// !sign_eq => (inc(x) = inc(y))
// ->
// inc(y) := sign_eq != inc(x)
//
template<typename Ext>
typename simplex<Ext>::var_t
simplex<Ext>::pick_var_to_leave(
var_t x_j, bool inc,
scoped_eps_numeral& gain, scoped_numeral& new_a_ij) {
var_t x_j, bool inc_x_j,
scoped_eps_numeral& gain, scoped_numeral& new_a_ij, bool& inc_x_i) {
var_t x_i = null_var;
gain.reset();
scoped_eps_numeral curr_gain(em);
@ -818,10 +840,13 @@ namespace simplex {
var_info& vi = m_vars[s];
numeral const& a_ij = it.get_row_entry().m_coeff;
numeral const& a_ii = vi.m_base_coeff;
bool inc_s = (m.is_pos(a_ii) != m.is_pos(a_ij)) ? inc : !inc;
TRACE("simplex", tout << "v" << x_j << " base v" << s << " incs: " << inc_s
<< " upper valid:" << vi.m_upper_valid
<< " lower valid:" << vi.m_lower_valid << "\n";
bool sign_eq = (m.is_pos(a_ii) == m.is_pos(a_ij));
bool inc_s = sign_eq != inc_x_j;
TRACE("simplex", tout << "x_j: v" << x_j << ", base x_i: v" << s
<< ", inc_x_i: " << inc_s
<< ", inc_x_j: " << inc_x_j
<< ", upper valid:" << vi.m_upper_valid
<< ", lower valid:" << vi.m_lower_valid << "\n";
display_row(tout, r););
if ((inc_s && !vi.m_upper_valid) || (!inc_s && !vi.m_lower_valid)) {
continue;
@ -841,6 +866,7 @@ namespace simplex {
x_i = s;
gain = curr_gain;
new_a_ij = a_ij;
inc_x_i = inc_s;
TRACE("simplex", tout << "x_j v" << x_j << " x_i v" << x_i << " gain: ";
tout << curr_gain << "\n";);
}