3
0
Fork 0
mirror of https://github.com/Z3Prover/z3 synced 2025-04-08 18:31:49 +00:00

fixing bounds calculation

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2017-01-13 17:05:51 -08:00
parent cb6c6332b3
commit 975474f560
2 changed files with 156 additions and 37 deletions

View file

@ -28,6 +28,7 @@ Notes:
#include "pb_rewriter_def.h"
#include "sparse_matrix_def.h"
#include "simplex_def.h"
#include "mpz.h"
namespace smt {
@ -244,7 +245,15 @@ namespace smt {
SASSERT(m_bound > 0);
SASSERT(ctx.get_assignment(lit) == l_false);
unsigned index = m_bound + 1;
for (unsigned i = 0; i <= m_bound; ++i) {
//
// We give preference to a watched literal in position 1..m_bound.
// Notice, that if a literal occurs multiple
// times in m_args, within [0..m_bound] then it is inserted into the watch
// list for this cardinality constraint. For each occurrence, a callback
// to assign is made.
//
for (unsigned i = m_bound + 1; i > 0; ) {
--i;
if (m_args[i] == lit) {
index = i;
break;
@ -261,9 +270,6 @@ namespace smt {
if (ctx.get_assignment(lit2) != l_false) {
TRACE("pb", tout << "swap " << lit2 << "\n";);
std::swap(m_args[index], m_args[i]);
if (ctx.get_assignment(m_args[0]) == l_false) {
std::swap(m_args[0], m_args[index]);
}
th.watch_literal(lit2, this);
return l_undef;
}
@ -1016,9 +1022,8 @@ namespace smt {
}
lits.push_back(lit);
ctx.mk_th_axiom(get_id(), lits.size(), lits.c_ptr());
lit.neg();
for (unsigned i = 0; i < c->size(); ++i) {
literal lits2[2] = { lit, c->lit(i) };
literal lits2[2] = { ~lit, c->lit(i) };
ctx.mk_th_axiom(get_id(), 2, lits2);
}
dealloc(c);
@ -1104,7 +1109,7 @@ namespace smt {
m_stats.m_num_conflicts++;
context& ctx = get_context();
justification* js = 0;
if (proofs_enabled()) {
if (proofs_enabled()) {
js = alloc(theory_lemma_justification, get_id(), ctx, lits.size(), lits.c_ptr());
}
resolve_conflict(c, lits);
@ -1117,7 +1122,6 @@ namespace smt {
m_stats.m_num_propagations++;
context& ctx = get_context();
TRACE("pb", tout << "#prop: " << c.num_propagations() << " - " << lits << " " << c.lit() << " => " << l << "\n";);
ctx.assign(l, ctx.mk_justification(
card_justification(
c, get_id(), ctx.get_region(), lits.size(), lits.c_ptr(), l)));
@ -1910,9 +1914,7 @@ namespace smt {
ctx.set_mark(v);
++m_num_marks;
}
if (lvl > ctx.get_base_level()) {
inc_coeff(l, offset);
}
inc_coeff(l, offset);
}
void theory_pb::process_card(card& c, int offset) {
@ -1930,25 +1932,113 @@ namespace smt {
SASSERT(ctx.get_assignment(c.lit()) == l_true);
}
void theory_pb::inc_coeff(literal l, int offset) {
if (l.sign()) {
m_bound -= offset;
void theory_pb::validate_lemma() {
uint_set seen;
int value = -m_bound;
context& ctx = get_context();
for (unsigned i = 0; i < m_active_coeffs.size(); ++i) {
bool_var v = m_active_coeffs[i];
if (seen.contains(v)) {
continue;
}
seen.insert(v);
int coeff = get_coeff(v);
if (coeff == 0) continue;
if (coeff < 0 && ctx.get_assignment(v) != l_true) {
value -= coeff;
}
else if (coeff > 0 && ctx.get_assignment(v) != l_false) {
value += coeff;
}
}
std::cout << "bound: " << m_bound << " value " << value << " lemma is " << (value >= 0 ? "sat" : "unsat") << "\n";
}
void theory_pb::inc_coeff(literal l, int offset) {
SASSERT(offset > 0);
bool_var v = l.var();
SASSERT(v != null_bool_var);
if (static_cast<bool_var>(m_coeffs.size()) <= v) {
m_coeffs.resize(v + 1, 0);
}
if (m_coeffs[v] == 0) {
int coeff0 = m_coeffs[v];
if (coeff0 == 0) {
m_active_coeffs.push_back(v);
}
int inc = l.sign() ? -offset : offset;
m_coeffs[v] += inc;
int coeff1 = inc + coeff0;
m_coeffs[v] = coeff1;
if (coeff0 > 0 && 0 > coeff1) {
m_bound += coeff1;
}
else if (coeff0 < 0 && 0 < coeff1) {
m_bound += coeff0;
}
}
/**
\brief attempt a cut and simplification of constraints.
*/
void theory_pb::cut() {
unsigned g = 0;
for (unsigned i = 0; i < m_active_coeffs.size(); ++i) {
bool_var v = m_active_coeffs[i];
int coeff = m_coeffs[v];
if (coeff == 0) {
m_active_coeffs[i] = m_active_coeffs.back();
m_active_coeffs.pop_back();
continue;
}
if (coeff < 0) {
coeff = -coeff;
}
if (m_bound < coeff) {
m_coeffs[v] = m_bound;
}
if (g == 0) {
g = static_cast<unsigned>(coeff);
}
else if (g != 1) {
g = u_gcd(g, static_cast<unsigned>(coeff));
}
}
if (g != 1 && g != 0) {
uint_set seen;
for (unsigned i = 0; i < m_active_coeffs.size(); ++i) {
bool_var v = m_active_coeffs[i];
if (!seen.contains(v)) {
seen.insert(v);
m_coeffs[v] /= g;
}
}
m_bound /= g;
TRACE("pb", display_resolved_lemma(tout << "cut\n"););
}
}
#if 0
void theory_pb::reduce2(int s1, int alpha, bool_var v, card& asserting) {
// m_coeffs one for each boolean variable.
int beta = coeff_of(v);
if (beta == 1) {
process_card(asserting, alpha);
return;
}
int s2 = slack(asserting);
while (beta * s1 + s2 * alpha >= 0) {
bool_var x = pick_var(asserting);
reduce();
reduce_degree();
s2 = s2 + delta_slack;
}
}
#endif
bool theory_pb::resolve_conflict(card& c, literal_vector const& confl) {
TRACE("pb", display(tout, c, true); get_context().display(tout););
TRACE("pb", display(tout, c, true); );
bool_var v;
context& ctx = get_context();
@ -1966,9 +2056,11 @@ namespace smt {
m_num_marks = 0;
m_bound = c.k();
m_antecedents.reset();
m_resolved.reset();
literal_vector ante;
process_card(c, 1);
// point into stack of assigned literals
literal_vector const& lits = ctx.assigned_literals();
@ -1977,12 +2069,12 @@ namespace smt {
b_justification js;
literal conseq = ~confl[2];
while (m_num_marks > 0) {
v = conseq.var();
TRACE("pb", display_resolved_lemma(tout << conseq << "\n"););
int offset = get_coeff(v);
if (offset == 0) {
@ -1991,19 +2083,20 @@ namespace smt {
else if (offset < 0) {
offset = -offset;
}
SASSERT(offset > 0);
js = ctx.get_justification(v);
TRACE("pb", tout << "conseq: " << conseq << "\n";);
validate_lemma();
// ctx.display(std::cout, js);
inc_coeff(conseq, offset);
m_bound += offset;
//
// Resolve selected conseq with antecedents.
//
int bound = 1;
switch(js.get_kind()) {
case b_justification::CLAUSE: {
@ -2016,7 +2109,7 @@ namespace smt {
}
unsigned num_lits = cls.get_num_literals();
if (cls.get_literal(0) == conseq) {
process_antecedent(cls.get_literal(1), offset);
process_antecedent(cls.get_literal(1), offset);
}
else {
SASSERT(cls.get_literal(1) == conseq);
@ -2047,12 +2140,14 @@ namespace smt {
}
else {
process_card(pbj->get_card(), offset);
bound = pbj->get_card().k();
}
break;
}
default:
UNREACHABLE();
}
m_bound += offset * bound;
process_next_resolvent:
@ -2068,11 +2163,30 @@ namespace smt {
SASSERT(ctx.get_assign_level(v) == m_conflict_lvl);
ctx.unset_mark(v);
m_resolved.push_back(idx);
--idx;
--m_num_marks;
}
validate_lemma();
TRACE("pb", display_resolved_lemma(tout << "done\n"););
uint_set seen;
int count = 0, sz = 0;
for (unsigned i = 0; i < m_active_coeffs.size(); ++i) {
bool_var v = m_active_coeffs[i];
if (seen.contains(v)) {
continue;
}
seen.insert(v);
int coeff = get_coeff(v);
if (coeff == 0) continue;
if (coeff < 0) coeff = -coeff;
++sz;
count += coeff;
}
std::cout << "New " << count << "(" << sz << ") >= " << m_bound << " " << c.size() << " >= " << c.k() << " new diff: " << count - m_bound << " old diff: " << c.size() - c.k() << "\n";
return true;
}
@ -2188,19 +2302,18 @@ namespace smt {
unsigned lvl;
out << "num marks: " << m_num_marks << "\n";
out << "conflict level: " << m_conflict_lvl << "\n";
for (unsigned i = lits.size(); i > 0;) {
--i;
v = lits[i].var();
for (unsigned i = 0; i < m_resolved.size(); ++i) {
v = lits[m_resolved[i]].var();
lvl = ctx.get_assign_level(v);
out << lvl << ": " << lits[i] << " " << (ctx.is_marked(v)?"m":"u") << " ";
out << lvl << ": " << lits[i] << " ";
ctx.display(out, ctx.get_justification(v));
}
if (!m_antecedents.empty()) {
out << m_antecedents << " ==> ";
}
int bound = m_bound;
uint_set seen;
bool first = true;
for (unsigned i = 0; i < m_active_coeffs.size(); ++i) {
bool_var v = m_active_coeffs[i];
if (seen.contains(v)) {
@ -2209,24 +2322,26 @@ namespace smt {
seen.insert(v);
int coeff = get_coeff(v);
if (coeff == 0) {
// skip
continue;
}
else if (coeff == 1) {
out << literal(v) << " ";
if (!first) {
out << " + ";
}
if (coeff == 1) {
out << literal(v);
}
else if (coeff == -1) {
out << literal(v, true) << " ";
bound -= coeff;
out << literal(v, true);
}
else if (coeff > 0) {
out << coeff << " " << literal(v) << " ";
out << coeff << " * " << literal(v);
}
else {
out << (-coeff) << " " << literal(v, true) << " ";
bound -= coeff;
out << (-coeff) << " * " << literal(v, true);
}
first = false;
}
out << " >= " << bound << "\n";
out << " >= " << m_bound << "\n";
}
std::ostream& theory_pb::display(std::ostream& out, arg_t const& c, bool values) const {

View file

@ -365,6 +365,7 @@ namespace smt {
// Conflict resolution, cutting plane derivation.
//
unsigned m_num_marks;
unsigned_vector m_resolved;
unsigned m_conflict_lvl;
svector<int> m_coeffs;
svector<bool_var> m_active_coeffs;
@ -379,8 +380,11 @@ namespace smt {
bool resolve_conflict(card& c, literal_vector const& conflict_clause);
void process_antecedent(literal l, int offset);
void process_card(card& c, int offset);
void cut();
bool is_proof_justification(justification const& j) const;
void validate_lemma();
void hoist_maximal_values();
void validate_final_check();