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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2021-05-15 10:12:11 -07:00
parent 683ce27c8f
commit 88bbe9d54e
6 changed files with 164 additions and 54 deletions
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160
src/math/polysat/linear_solver.cpp
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@ -27,34 +27,31 @@ namespace polysat {
case trail_i::inc_level_i:
--n;
break;
case trail_i::add_var_i:
NOT_IMPLEMENTED_YET();
case trail_i::add_var_i: {
auto [v, sz] = m_rows.back();
--m_sz2num_vars[sz];
m_rows.pop_back();
break;
}
case trail_i::set_bound_i: {
auto [v, sz] = m_rows.back();
sz2fixplex(sz).restore_bound();
m_rows.pop_back();
break;
}
case trail_i::set_value_i:
break;
case trail_i::add_row_i: {
auto [v, sz] = m_rows.back();
sz2fixplex(sz).del_row(v);
m_rows.pop_back();
break;
}
case trail_i::activate_constraint_i:
// not needed?
NOT_IMPLEMENTED_YET();
break;
default:
UNREACHABLE();
}
m_trail.pop_back();
}
}
fixplex_base& linear_solver::sz2fixplex(unsigned sz) {
fixplex_base* b = m_fix.get(sz, nullptr);
if (!b) {
@ -74,51 +71,107 @@ namespace polysat {
m_fix.set(sz, b);
}
return *b;
}
}
var_t linear_solver::internalize_pdd(pdd const& p) {
unsigned sz = p.power_of_2();
linearize(p);
if (m_vars.size() == 1 && m_coeffs.back() == 1)
return m_vars.back();
var_t v = fresh_var(sz);
m_vars.push_back(v);
m_coeffs.push_back(rational::power_of_two(sz) - 1);
sz2fixplex(sz).add_row(v, m_vars.size(), m_vars.data(), m_coeffs.data());
m_rows.push_back(std::make_pair(v, sz));
m_trail.push_back(trail_i::add_row_i);
return v;
}
/**
* create the row c.p() - v == 0
* when equality is asserted, set range on v as v == 0 or v > 0.
*/
void linear_solver::new_eq(eq_constraint& c) {
pdd p = c.p();
var_t v = internalize_pdd(c.p());
m_bool_var2row.setx(c.bvar(), v, UINT_MAX);
}
void linear_solver::assert_eq(eq_constraint& c) {
var_t v = m_bool_var2row[c.bvar()];
pdd p = c.p();
unsigned sz = p.power_of_2();
auto& fp = sz2fixplex(sz);
m_trail.push_back(trail_i::set_bound_i);
m_rows.push_back(std::make_pair(v, sz));
if (c.is_positive())
fp.set_bounds(v, rational::zero(), rational::zero());
else
fp.set_bounds(v, rational::one(), rational::power_of_two(sz) - 1);
}
void linear_solver::new_le(ule_constraint& c) {
var_t v = internalize_pdd(c.lhs());
m_bool_var2row.setx(c.bvar(), v, UINT_MAX);
var_t w = internalize_pdd(c.rhs());
m_bool_var2row.setx(c.bvar(), w, UINT_MAX);
// todo: track both variables
}
void linear_solver::assert_le(ule_constraint& c) {
// 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::new_bit(var_constraint& c) {
}
void linear_solver::assert_bit(var_constraint& c) {
}
void linear_solver::new_constraint(constraint& c) {
switch (c.kind()) {
case ckind_t::eq_t: {
//
// create the row c.p() - v == 0
// when equality is asserted, set range on v as v == 0 or v > 0.
//
pdd p = c.to_eq().p();
unsigned sz = p.power_of_2();
linearize(p);
var_t v = fresh_var(sz);
m_vars.push_back(v);
m_coeffs.push_back(rational::power_of_two(sz) - 1);
sz2fixplex(sz).add_row(v, m_vars.size(), m_vars.data(), m_coeffs.data());
m_rows.push_back(std::make_pair(v, sz));
m_trail.push_back(trail_i::add_row_i);
m_bool_var2row.setx(c.bvar(), v, UINT_MAX);
break;
}
case ckind_t::eq_t:
new_eq(c.to_eq());
break;
case ckind_t::ule_t:
new_le(c.to_ule());
break;
case ckind_t::bit_t:
new_bit(c.to_bit());
break;
default:
UNREACHABLE();
break;
}
}
void linear_solver::activate_constraint(constraint& c) {
switch (c.kind()) {
case ckind_t::eq_t: {
var_t v = m_bool_var2row[c.bvar()];
pdd p = c.to_eq().p();
unsigned sz = p.power_of_2();
auto& fp = sz2fixplex(sz);
m_trail.push_back(trail_i::set_bound_i);
m_rows.push_back(std::make_pair(v, sz));
if (c.is_positive())
fp.set_bounds(v, rational::zero(), rational::zero());
else
fp.set_bounds(v, rational::one(), rational::power_of_two(sz) - 1);
break;
}
case ckind_t::eq_t:
assert_eq(c.to_eq());
break;
case ckind_t::ule_t:
assert_le(c.to_ule());
break;
case ckind_t::bit_t:
assert_bit(c.to_bit());
break;
default:
UNREACHABLE();
break;
}
}
@ -138,28 +191,45 @@ namespace polysat {
return 0;
}
var_t linear_solver::fresh_var(unsigned sz) {
var_t linear_solver::pvar2var(unsigned sz, pvar v) {
NOT_IMPLEMENTED_YET();
return 0;
}
var_t linear_solver::fresh_var(unsigned sz) {
m_sz2num_vars.reserve(sz + 1);
m_trail.push_back(trail_i::add_var_i);
m_rows.push_back(std::make_pair(0, sz));
return m_sz2num_vars[sz]++;
}
void linear_solver::set_value(pvar v, rational const& value) {
unsigned sz = s.size(v);
auto& fp = sz2fixplex(sz);
var_t w = pvar2var(sz, v);
m_trail.push_back(trail_i::set_bound_i);
m_rows.push_back(std::make_pair(w, sz));
fp.set_value(w, value);
}
void linear_solver::set_bound(pvar v, rational const& lo, rational const& hi) {
unsigned sz = s.size(v);
auto& fp = sz2fixplex(sz);
var_t w = pvar2var(sz, v);
m_trail.push_back(trail_i::set_bound_i);
m_rows.push_back(std::make_pair(v, sz));
fp.set_bounds(v, lo, hi);
m_rows.push_back(std::make_pair(w, sz));
fp.set_bounds(w, lo, hi);
}
// check integer modular feasibility under current bounds.
lbool linear_solver::check() {
return l_undef;
lbool res = l_true;
// loop over fp solvers that have been touched and use make_feasible.
return res;
}
void linear_solver::unsat_core(unsigned_vector& deps) {
NOT_IMPLEMENTED_YET();
}
// current value assigned to (linear) variable according to tableau.