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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2021-05-21 18:03:05 -07:00
parent 28996429df
commit 5ad486901e
4 changed files with 70 additions and 13 deletions
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61
src/math/polysat/linear_solver.cpp
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@ -128,19 +128,58 @@ namespace polysat {
m_bool_var2row.setx(c.bvar(), pr, pr);
}
//
// v <= w:
// static constraints:
// - lo(v) <= lo(w)
// - hi(v) <= hi(w)
//
// special case for inequalities with constant bounds
// bounds propagation on fp, then bounds strengthening
// based on static constraints
// internal backtrack search over bounds
// inequality graph (with offsets)
//
void linear_solver::assert_le(ule_constraint& c) {
auto [v, w] = m_bool_var2row[c.bvar()];
// v <= w:
// static constraints:
// - lo(v) <= lo(w)
// - hi(v) <= hi(w)
//
// special case for inequalities with constant bounds
// bounds propagation on fp, then bounds strengthening
// based on static constraints
// internal backtrack search over bounds
// inequality graph (with offsets)
//
unsigned sz = c.lhs().power_of_2();
auto& fp = sz2fixplex(sz);
rational z(0);
if (c.rhs().is_val()) {
bool is_max_value = false;
if (c.is_positive())
// v <= rhs
fp.set_bounds(v, z, c.rhs().val());
else if (is_max_value)
throw default_exception("conflict not implemented");
else
// rhs < v
fp.set_bounds(v, c.rhs().val() + 1, z);
m_trail.push_back(trail_i::set_bound_i);
m_rows.push_back(std::make_pair(v, sz));
return;
}
if (c.lhs().is_val()) {
if (c.is_positive())
// w >= lhs
fp.set_bounds(w, c.lhs().val(), z);
else if (c.lhs().val() == 0)
throw default_exception("conflict not implemented");
else
// w < lhs
fp.set_bounds(w, z, c.lhs().val() - 1);
m_trail.push_back(trail_i::set_bound_i);
m_rows.push_back(std::make_pair(w, sz));
return;
}
if (c.is_positive())
fp.add_le(v, w);
else
fp.add_lt(w, v);
}
void linear_solver::new_bit(var_constraint& c) {