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qsat-opt

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2016-04-28 21:31:16 -07:00
parent c414c6b5fd
commit c75fd02c95
5 changed files with 145 additions and 33 deletions
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100
src/qe/qe_arith.cpp
View file

@ -28,6 +28,7 @@ Revision History:
#include "expr_functors.h"
#include "model_v2_pp.h"
#include "expr_safe_replace.h"
#include "model_based_opt.h"
namespace qe {
@ -98,6 +99,55 @@ namespace qe {
}
}
void linearize(model& model, opt::model_based_opt& mbo, expr* lit, obj_map<expr, unsigned>& tids) {
obj_map<expr, rational> ts;
rational c(0), mul(1);
expr_ref t(m);
opt::ineq_type ty = opt::t_le;
expr* e1, *e2;
bool is_not = m.is_not(lit, lit);
if (is_not) {
mul.neg();
}
SASSERT(!m.is_not(lit));
if (a.is_le(lit, e1, e2) || a.is_ge(lit, e2, e1)) {
if (is_not) mul.neg();
linearize(model, mul, e1, c, ts);
linearize(model, -mul, e2, c, ts);
ty = is_not ? opt::t_lt : opt::t_le;
}
else if (a.is_lt(lit, e1, e2) || a.is_gt(lit, e2, e1)) {
if (is_not) mul.neg();
linearize(model, mul, e1, c, ts);
linearize(model, -mul, e2, c, ts);
ty = is_not ? opt::t_le: opt::t_lt;
}
else if (m.is_eq(lit, e1, e2) && !is_not && is_arith(e1)) {
linearize(model, mul, e1, c, ts);
linearize(model, -mul, e2, c, ts);
ty = opt::t_eq;
}
else if (m.is_distinct(lit) && !is_not && is_arith(to_app(lit)->get_arg(0))) {
UNREACHABLE();
}
else if (m.is_distinct(lit) && is_not && is_arith(to_app(lit)->get_arg(0))) {
UNREACHABLE();
}
else if (m.is_eq(lit, e1, e2) && is_not && is_arith(e1)) {
UNREACHABLE();
}
else {
return;
}
if (ty == opt::t_lt && is_int()) {
c += rational(1);
ty = opt::t_le;
}
vars coeffs;
extract_coefficients(ts, tids, coeffs);
mbo.add_constraint(coeffs, c, ty);
}
void linearize(model& model, rational const& mul, expr* t, rational& c, obj_map<expr, rational>& ts) {
expr* t1, *t2, *t3;
rational mul1;
@ -913,18 +963,54 @@ namespace qe {
return true;
}
typedef opt::model_based_opt::var var;
typedef vector<var> vars;
opt::bound_type maximize(expr_ref_vector const& fmls, model& mdl, app* t, expr_ref& value, expr_ref& bound) {
opt::model_based_opt mbo;
obj_map<expr, rational> ts;
obj_map<expr, unsigned> tids;
vars coeffs;
rational c(0), mul(1);
linearize(mdl, mul, t, c, ts);
// TBD:
// pick variables one by one from ts.
// m_var = alloc(contains_app, m, v);
// perform upper or lower projection depending on sign of v.
//
return opt::unbounded;
extract_coefficients(ts, tids, coeffs);
mbo.set_objective(coeffs, c);
for (unsigned i = 0; i < fmls.size(); ++i) {
linearize(mdl, mbo, fmls[i], tids);
}
rational val;
opt::bound_type result = mbo.maximize(val);
value = a.mk_numeral(val, false);
switch (result) {
case opt::unbounded:
bound = m.mk_false();
break;
case opt::strict:
bound = a.mk_le(value, t);
break;
case opt::non_strict:
bound = a.mk_lt(value, t);
break;
}
return result;
}
void extract_coefficients(obj_map<expr, rational> const& ts, obj_map<expr, unsigned>& tids, vars& coeffs) {
coeffs.reset();
obj_map<expr, rational>::iterator it = ts.begin(), end = ts.end();
for (; it != end; ++it) {
unsigned id;
if (!tids.find(it->m_key, id)) {
id = tids.size();
tids.insert(it->m_key, id);
}
coeffs.push_back(var(id, it->m_value));
}
}
};
arith_project_plugin::arith_project_plugin(ast_manager& m) {

18
src/qe/qsat.cpp
View file

@ -1326,25 +1326,9 @@ namespace qe {
void maximize(expr_ref_vector const& core, model& mdl) {
TRACE("qe", tout << "maximize: " << core << "\n";);
m_was_sat |= !core.empty();
if (core.empty()) {
m_ex.assert_expr(m.mk_false());
m_fa.assert_expr(m.mk_false());
return;
}
expr_ref bound(m);
m_bound = m_mbp.maximize(core, mdl, m_objective, m_value, bound);
switch (m_bound) {
case opt::unbounded:
m_ex.assert_expr(m.mk_false());
m_fa.assert_expr(m.mk_false());
break;
case opt::strict:
m_ex.assert_expr(bound);
break;
case opt::non_strict:
m_ex.assert_expr(bound);
break;
}
m_ex.assert_expr(bound);
}
};