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use PB solver instead of full arithmetic for bouding Pareto fronts so that difference logic theory isn't broken. Codeplex issue 175

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2015-02-22 09:46:21 -08:00
parent 49483fdc28
commit c3232693f0
5 changed files with 51 additions and 54 deletions
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92
src/opt/opt_context.cpp
View file

@ -327,78 +327,66 @@ namespace opt {
expr_ref context::mk_le(unsigned i, model_ref& mdl) {
objective const& obj = m_objectives[i];
expr_ref val(m), result(m), term(m);
mk_term_val(mdl, obj, term, val);
switch (obj.m_type) {
case O_MINIMIZE:
result = mk_ge(term, val);
break;
case O_MAXSMT:
result = mk_ge(term, val);
break;
case O_MAXIMIZE:
result = mk_ge(val, term);
break;
}
return result;
return mk_cmp(false, mdl, obj);
}
expr_ref context::mk_ge(unsigned i, model_ref& mdl) {
objective const& obj = m_objectives[i];
expr_ref val(m), result(m), term(m);
mk_term_val(mdl, obj, term, val);
switch (obj.m_type) {
case O_MINIMIZE:
result = mk_ge(val, term);
break;
case O_MAXSMT:
result = mk_ge(val, term);
break;
case O_MAXIMIZE:
result = mk_ge(term, val);
break;
}
return result;
return mk_cmp(true, mdl, obj);
}
expr_ref context::mk_gt(unsigned i, model_ref& mdl) {
expr_ref result = mk_le(i, mdl);
result = m.mk_not(result);
return result;
}
void context::mk_term_val(model_ref& mdl, objective const& obj, expr_ref& term, expr_ref& val) {
rational r;
expr_ref context::mk_cmp(bool is_ge, model_ref& mdl, objective const& obj) {
rational k(0);
expr_ref val(m), result(m);
switch (obj.m_type) {
case O_MINIMIZE:
is_ge = !is_ge;
case O_MAXIMIZE:
term = obj.m_term;
break;
case O_MAXSMT: {
unsigned sz = obj.m_terms.size();
expr_ref_vector sum(m);
expr_ref zero(m);
zero = m_arith.mk_numeral(rational(0), false);
for (unsigned i = 0; i < sz; ++i) {
expr* t = obj.m_terms[i];
rational const& w = obj.m_weights[i];
sum.push_back(m.mk_ite(t, m_arith.mk_numeral(w, false), zero));
}
if (sum.empty()) {
term = zero;
VERIFY(mdl->eval(obj.m_term, val) && is_numeral(val, k));
if (is_ge) {
result = mk_ge(obj.m_term, val);
}
else {
term = m_arith.mk_add(sum.size(), sum.c_ptr());
}
result = mk_ge(val, obj.m_term);
}
break;
case O_MAXSMT: {
m_opt_solver->ensure_pb();
pb_util pb(m);
unsigned sz = obj.m_terms.size();
ptr_vector<expr> terms;
vector<rational> coeffs;
for (unsigned i = 0; i < sz; ++i) {
terms.push_back(obj.m_terms[i]);
coeffs.push_back(obj.m_weights[i]);
VERIFY(mdl->eval(obj.m_terms[i], val));
if (m.is_true(val)) {
k += obj.m_weights[i];
}
}
if (is_ge) {
result = pb.mk_ge(sz, coeffs.c_ptr(), terms.c_ptr(), k);
}
else {
result = pb.mk_le(sz, coeffs.c_ptr(), terms.c_ptr(), k);
}
break;
}
}
TRACE("opt",
model_smt2_pp(tout << "Model:\n", m, *mdl, 0);
mdl->eval(term, val); tout << term << " " << val << "\n";);
VERIFY(mdl->eval(term, val) && is_numeral(val, r));
}
tout << (is_ge?">= ":"<= ") << k << "\n";
display_objective(tout, obj);
tout << "\n";
tout << result << "\n";);
return result;
}
expr_ref context::mk_ge(expr* t, expr* s) {
expr_ref result(m);

2
src/opt/opt_context.h
View file

@ -282,7 +282,7 @@ namespace opt {
// pareto
void yield();
expr_ref mk_ge(expr* t, expr* s);
void mk_term_val(model_ref& mdl, objective const& obj, expr_ref& term, expr_ref& val);
expr_ref mk_cmp(bool is_ge, model_ref& mdl, objective const& obj);
};

2
src/opt/opt_pareto.cpp
View file

@ -68,7 +68,7 @@ namespace opt {
fmls.push_back(m.mk_or(gt.size(), gt.c_ptr()));
fml = m.mk_and(fmls.size(), fmls.c_ptr());
IF_VERBOSE(10, verbose_stream() << "dominates: " << fml << "\n";);
TRACE("opt", tout << fml << "\n";);
TRACE("opt", tout << fml << "\n"; model_smt2_pp(tout, m, *m_model, 0););
m_solver->assert_expr(fml);
}

8
src/opt/opt_solver.cpp
View file

@ -86,6 +86,14 @@ namespace opt {
m_context.set_logic(logic);
}
void opt_solver::ensure_pb() {
smt::theory_id th_id = m.get_family_id("pb");
smt::theory* th = get_context().get_theory(th_id);
if (!th) {
get_context().register_plugin(alloc(smt::theory_pb, m, m_params));
}
}
smt::theory_opt& opt_solver::get_optimizer() {
smt::context& ctx = m_context.get_context();
smt::theory_id arith_id = m_context.m().get_family_id("arith");

1
src/opt/opt_solver.h
View file

@ -122,6 +122,7 @@ namespace opt {
bool dump_benchmarks();
smt::context& get_context() { return m_context.get_context(); } // used by weighted maxsat.
void ensure_pb();
smt::theory_opt& get_optimizer();