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add bvsls module as backend to weighted maxsat

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2014-03-28 13:32:31 -07:00
parent a26e299390
commit 3d7f208ce6
5 changed files with 3499 additions and 54 deletions
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60
src/opt/weighted_maxsat.cpp
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@ -33,6 +33,7 @@ Notes:
#include "qfbv_tactic.h"
#include "card2bv_tactic.h"
#include "tactic2solver.h"
#include "bvsls_opt_engine.h"
namespace smt {
@ -463,11 +464,14 @@ namespace opt {
ref<solver> m_sat_solver;
scoped_ptr<imp> m_imp;
smt::pb_sls m_sls;
bvsls_opt_engine m_bvsls;
imp(ast_manager& m, opt_solver& s, expr_ref_vector const& soft_constraints, vector<rational> const& weights):
m(m), s(s), m_soft(soft_constraints), m_weights(weights), m_print_all_models(false), m_cancel(false),
m_solver(m, m_params, symbol("bound")),
m_sls(m)
m_sls(m),
m_bvsls(m, m_params)
{
m_assignment.resize(m_soft.size(), false);
}
@ -534,6 +538,9 @@ namespace opt {
if (m_engine == symbol("sls")) {
return sls_solve();
}
if (m_engine == symbol("bvsls")) {
return bvsls_solve();
}
if (m_engine == symbol::null || m_engine == symbol("wmax")) {
return incremental_solve();
}
@ -687,6 +694,57 @@ namespace opt {
return is_sat;
}
lbool bvsls_solve() {
IF_VERBOSE(1, verbose_stream() << "(bvsls solve)\n";);
bv_util bv(m);
pb::card_pb_rewriter pb_rewriter(m);
expr_ref tmp(m), objective(m), zero(m);
expr_ref_vector es(m);
for (unsigned i = 0; i < s.get_num_assertions(); ++i) {
pb_rewriter(s.get_assertion(i), tmp);
m_bvsls.assert_expr(tmp);
}
m_lower = m_upper = rational::zero();
for (unsigned i = 0; i < m_soft.size(); ++i) {
m_upper += m_weights[i];
}
rational num = numerator(m_upper);
rational den = denominator(m_upper);
rational maxval = num*den;
unsigned bv_size = maxval.get_num_bits();
zero = bv.mk_numeral(rational(0), bv_size);
for (unsigned i = 0; i < m_soft.size(); ++i) {
es.push_back(m.mk_ite(m_soft[i].get(), bv.mk_numeral(den*m_weights[i], bv_size), zero));
}
if (es.empty()) {
objective = bv.mk_numeral(0, bv_size);
}
else {
objective = es[0].get();
for (unsigned i = 1; i < es.size(); ++i) {
objective = bv.mk_bv_add(objective, es[i].get());
}
}
// TBD: can we set an initial model on m_bvsls?
bvsls_opt_engine::optimization_result res = m_bvsls.optimize(objective);
switch(res.is_sat) {
case l_true: {
unsigned bv_size = 0;
// TBD: m_bvsls.get_model(m_model);
VERIFY(bv.is_numeral(res.optimum, m_lower, bv_size));
break;
}
case l_false:
case l_undef:
break;
}
return res.is_sat;
}
/**
Iteratively increase cost until there is an assignment during
final_check that satisfies min_cost.