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add integer branch and bound to nlsat

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2017-12-14 17:07:17 -08:00
parent 58c6cb87c3
commit e5fa35e969
4 changed files with 68 additions and 10 deletions
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4
src/nlsat/nlsat_interval_set.cpp
View file

@ -672,14 +672,14 @@ namespace nlsat {
return new_set;
}
void interval_set_manager::peek_in_complement(interval_set const * s, anum & w, bool randomize) {
void interval_set_manager::peek_in_complement(interval_set const * s, bool is_int, anum & w, bool randomize) {
SASSERT(!is_full(s));
if (s == 0) {
if (randomize) {
int num = m_rand() % 2 == 0 ? 1 : -1;
#define MAX_RANDOM_DEN_K 4
int den_k = (m_rand() % MAX_RANDOM_DEN_K);
int den = 1 << den_k;
int den = is_int ? 1 : (1 << den_k);
scoped_mpq _w(m_am.qm());
m_am.qm().set(_w, num, den);
m_am.set(w, _w);

2
src/nlsat/nlsat_interval_set.h
View file

@ -108,7 +108,7 @@ namespace nlsat {
\pre !is_full(s)
*/
void peek_in_complement(interval_set const * s, anum & w, bool randomize);
void peek_in_complement(interval_set const * s, bool is_int, anum & w, bool randomize);
};
typedef obj_ref<interval_set, interval_set_manager> interval_set_ref;

70
src/nlsat/nlsat_solver.cpp
View file

@ -903,15 +903,18 @@ namespace nlsat {
*/
lbool value(literal l) {
lbool val = assigned_value(l);
if (val != l_undef)
if (val != l_undef) {
return val;
}
bool_var b = l.var();
atom * a = m_atoms[b];
if (a == 0)
if (a == 0) {
return l_undef;
}
var max = a->max_var();
if (!m_assignment.is_assigned(max))
if (!m_assignment.is_assigned(max)) {
return l_undef;
}
val = to_lbool(m_evaluator.eval(a, l.sign()));
TRACE("value_bug", tout << "value of: "; display(tout, l); tout << " := " << val << "\n";
tout << "xk: " << m_xk << ", a->max_var(): " << a->max_var() << "\n";
@ -1168,7 +1171,7 @@ namespace nlsat {
void select_witness() {
scoped_anum w(m_am);
SASSERT(!m_ism.is_full(m_infeasible[m_xk]));
m_ism.peek_in_complement(m_infeasible[m_xk], w, m_randomize);
m_ism.peek_in_complement(m_infeasible[m_xk], m_is_int[m_xk], w, m_randomize);
TRACE("nlsat",
tout << "infeasible intervals: "; m_ism.display(tout, m_infeasible[m_xk]); tout << "\n";
tout << "assigning "; m_display_var(tout, m_xk); tout << "(x" << m_xk << ") -> " << w << "\n";);
@ -1232,6 +1235,61 @@ namespace nlsat {
}
}
lbool search_check() {
lbool r = l_undef;
while (true) {
r = search();
if (r != l_true) break;
random_gen r(++m_random_seed);
unsigned start = r(num_vars());
for (var y = 0; y < num_vars(); y++) {
var x = (y + start) % num_vars();
if (m_is_int[x] && m_assignment.is_assigned(x) && !m_am.is_int(m_assignment.value(x))) {
scoped_anum v(m_am), vlo(m_am), vhi(m_am);
rational lo, hi;
bool is_even = false;
v = m_assignment.value(x);
init_search();
m_am.int_lt(v, vlo);
m_am.int_gt(v, vhi);
if (!m_am.is_int(vlo)) break;
if (!m_am.is_int(vhi)) break;
m_am.to_rational(vlo, lo);
m_am.to_rational(vhi, hi);
// derive tight bounds.
while (true) {
lo++;
if (!m_am.gt(v, lo.to_mpq())) { lo--; break; }
}
while (true) {
hi--;
if (!m_am.lt(v, hi.to_mpq())) { hi++; break; }
}
polynomial_ref p(m_pm);
rational one(1);
m_lemma.reset();
p = m_pm.mk_linear(1, &one, &x, -lo);
poly* p1 = p.get();
m_lemma.push_back(~mk_ineq_literal(atom::GT, 1, &p1, &is_even));
p = m_pm.mk_linear(1, &one, &x, -hi);
poly* p2 = p.get();
m_lemma.push_back(~mk_ineq_literal(atom::LT, 1, &p2, &is_even));
// perform branch and bound
clause * cls = mk_clause(m_lemma.size(), m_lemma.c_ptr(), false, 0);
if (cls) {
TRACE("nlsat", display(tout << "conflict " << lo << " " << hi, *cls); tout << "\n";);
}
r = l_undef;
break;
}
}
}
return r;
}
lbool check() {
TRACE("nlsat_smt2", display_smt2(tout););
TRACE("nlsat_fd", tout << "is_full_dimensional: " << is_full_dimensional() << "\n";);
@ -1250,7 +1308,7 @@ namespace nlsat {
reordered = true;
}
sort_watched_clauses();
lbool r = search();
lbool r = search_check();
CTRACE("nlsat_model", r == l_true, tout << "model before restore order\n"; display_assignment(tout););
if (reordered)
restore_order();
@ -1929,7 +1987,7 @@ namespace nlsat {
for (var x = 0; x < num; x++) {
p.push_back(x);
}
random_gen r(m_random_seed);
random_gen r(++m_random_seed);
shuffle(p.size(), p.c_ptr(), r);
reorder(p.size(), p.c_ptr());
}

2
src/tactic/smtlogics/qfnia_tactic.cpp
View file

@ -107,7 +107,7 @@ tactic * mk_qfnia_tactic(ast_manager & m, params_ref const & p) {
simp_p.set_bool("som", true); // expand into sums of monomials
return and_then(mk_qfnia_premable(m, p),
or_else(mk_qfnia_sat_solver(m, p),
or_else(// mk_qfnia_sat_solver(m, p),
mk_qfnia_nlsat_solver(m, p),
and_then(using_params(mk_simplify_tactic(m), simp_p),
mk_smt_tactic())));