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add model correction

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2016-04-29 19:08:10 -07:00
parent c75fd02c95
commit 2428bf18f1
11 changed files with 156 additions and 65 deletions
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79
src/math/simplex/model_based_opt.cpp
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@ -97,9 +97,10 @@ namespace opt {
// e.g. t2/a2 >= t3/a3
// then replace a3*x + t3 by t3/a3 - t2/a2 <= 0
//
bound_type model_based_opt::maximize(rational& value) {
inf_eps model_based_opt::maximize() {
SASSERT(invariant());
unsigned_vector other;
unsigned_vector bound_trail, bound_vars;
while (!objective().m_vars.empty()) {
TRACE("opt", tout << "tableau\n";);
var v = objective().m_vars.back();
@ -120,17 +121,79 @@ namespace opt {
mul_add(m_objective_id, - coeff/bound_coeff, bound_row_index);
m_rows[bound_row_index].m_alive = false;
bound_trail.push_back(bound_row_index);
bound_vars.push_back(x);
}
else {
return unbounded;
return inf_eps::infinity();
}
}
value = objective().m_value;
if (objective().m_type == t_lt) {
return strict;
//
// update the evaluation of variables to satisfy the bound.
update_values(bound_vars, bound_trail);
rational value = objective().m_value;
if (objective().m_type == t_lt) {
return inf_eps(inf_rational(value, rational(-1)));
}
else {
return non_strict;
return inf_eps(inf_rational(value));
}
}
void model_based_opt::update_values(unsigned_vector const& bound_vars, unsigned_vector const& bound_trail) {
rational eps(0);
for (unsigned i = bound_trail.size(); i > 0; ) {
--i;
unsigned x = bound_vars[i];
row const& r = m_rows[bound_trail[i]];
rational val = r.m_coeff;
rational x_coeff;
vector<var> const& vars = r.m_vars;
for (unsigned j = 0; j < vars.size(); ++j) {
var const& v = vars[j];
if (x = v.m_id) {
x_coeff = v.m_coeff;
}
else {
val += m_var2value[v.m_id]*v.m_coeff;
}
}
SASSERT(!x_coeff.is_zero());
val /= -x_coeff;
// Adjust epsilon to be s
if (eps.is_zero() || (!val.is_zero() && eps > abs(val))) {
eps = abs(val)/rational(2);
}
if (eps.is_zero() || (!r.m_value.is_zero() && eps > abs(r.m_value))) {
eps = abs(r.m_value)/rational(2);
}
//
//
// ax + t < 0
// <=> x < -t/a
// <=> x := -t/a - epsilon
//
if (x_coeff.is_pos() && r.m_type == t_lt) {
val -= eps;
}
//
// -ax + t < 0
// <=> -ax < -t
// <=> -x < -t/a
// <=> x > t/a
// <=> x := t/a + epsilon
//
if (x_coeff.is_pos() && r.m_type == t_lt) {
val -= eps;
}
else if (x_coeff.is_neg() && r.m_type == t_lt) {
val += eps;
}
m_var2value[x] = val;
}
}
@ -343,6 +406,10 @@ namespace opt {
return v;
}
rational model_based_opt::get_value(unsigned var) {
return m_var2value[var];
}
void model_based_opt::set_row(unsigned row_id, vector<var> const& coeffs, rational const& c, ineq_type rel) {
row& r = m_rows[row_id];
rational val(c);