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sls: fix bug where unsat remains empty after a literal is flipped. The new satisfiable subset should be checked

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refined interface between solvers to expose fixed variables for tabu objectives
This commit is contained in:
Nikolaj Bjorner 2024-12-01 18:35:56 -08:00
parent 24c3cd38d1
commit e6feb8423a
8 changed files with 118 additions and 30 deletions
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27
src/ast/sls/sls_arith_base.cpp
View file

@ -1968,6 +1968,7 @@ namespace sls {
template<typename num_t>
bool arith_base<num_t>::set_value(expr* e, expr* v) {
if (!a.is_int_real(e))
return false;
var_t w = m_expr2var.get(e->get_id(), UINT_MAX);
@ -1984,7 +1985,14 @@ namespace sls {
}
if (n == value(w))
return true;
return update(w, n);
bool r = update(w, n);
if (!r) {
IF_VERBOSE(2,
verbose_stream() << "set value failed " << mk_pp(e, m) << " := " << mk_pp(v, m) << "\n";
display(verbose_stream(), w) << " := " << value(w) << "\n");
}
return r;
}
template<typename num_t>
@ -1996,6 +2004,23 @@ namespace sls {
return expr_ref(a.mk_numeral(m_vars[v].value().to_rational(), a.is_int(e)), m);
}
template<typename num_t>
bool arith_base<num_t>::is_fixed(expr* e, expr_ref& value) {
if (!a.is_int_real(e))
return false;
num_t n;
if (is_num(e, n)) {
value = expr_ref(a.mk_numeral(n.to_rational(), a.is_int(e)), m);
return true;
}
auto v = mk_term(e);
if (is_fixed(v)) {
value = expr_ref(a.mk_numeral(m_vars[v].value().to_rational(), a.is_int(e)), m);
return true;
}
return false;
}
template<typename num_t>
bool arith_base<num_t>::is_sat() {
invariant();

1
src/ast/sls/sls_arith_base.h
View file

@ -280,6 +280,7 @@ namespace sls {
void register_term(expr* e) override;
bool set_value(expr* e, expr* v) override;
expr_ref get_value(expr* e) override;
bool is_fixed(expr* e, expr_ref& value) override;
void initialize() override;
void propagate_literal(sat::literal lit) override;
bool propagate() override;

4
src/ast/sls/sls_arith_plugin.cpp
View file

@ -64,6 +64,10 @@ namespace sls {
WITH_FALLBACK(get_value(e));
}
bool arith_plugin::is_fixed(expr* e, expr_ref& value) {
WITH_FALLBACK(is_fixed(e, value));
}
void arith_plugin::initialize() {
APPLY_BOTH(initialize());
}

1
src/ast/sls/sls_arith_plugin.h
View file

@ -32,6 +32,7 @@ namespace sls {
~arith_plugin() override {}
void register_term(expr* e) override;
expr_ref get_value(expr* e) override;
bool is_fixed(expr* e, expr_ref& value) override;
void initialize() override;
void propagate_literal(sat::literal lit) override;
bool propagate() override;

22
src/ast/sls/sls_context.cpp
View file

@ -172,6 +172,7 @@ namespace sls {
}
void context::propagate_boolean_assignment() {
start_propagation:
reinit_relevant();
for (auto p : m_plugins)
@ -180,9 +181,12 @@ namespace sls {
for (sat::literal lit : root_literals())
propagate_literal(lit);
if (m_new_constraint)
return;
if (any_of(root_literals(), [&](sat::literal lit) { return !is_true(lit); })) {
if (unsat().empty())
goto start_propagation;
return;
}
while (!m_new_constraint && m.inc() && (!m_repair_up.empty() || !m_repair_down.empty())) {
while (!m_repair_down.empty() && !m_new_constraint && m.inc()) {
@ -258,9 +262,6 @@ namespace sls {
auto p = m_plugins.get(fid, nullptr);
if (p)
p->propagate_literal(lit);
if (!is_true(lit)) {
m_new_constraint = true;
}
}
bool context::is_true(expr* e) {
@ -291,6 +292,14 @@ namespace sls {
bool context::set_value(expr * e, expr * v) {
return any_of(m_plugins, [&](auto p) { return p && p->set_value(e, v); });
}
bool context::is_fixed(expr* e, expr_ref& value) {
if (m.is_value(e)) {
value = e;
return true;
}
return any_of(m_plugins, [&](auto p) { return p && p->is_fixed(e, value); });
}
bool context::is_relevant(expr* e) {
unsigned id = e->get_id();
@ -317,6 +326,7 @@ namespace sls {
m_constraint_trail.push_back(e);
add_clause(e);
m_new_constraint = true;
verbose_stream() << "add constraint\n";
++m_stats.m_num_constraints;
}

2
src/ast/sls/sls_context.h
View file

@ -42,6 +42,7 @@ namespace sls {
virtual family_id fid() { return m_fid; }
virtual void register_term(expr* e) = 0;
virtual expr_ref get_value(expr* e) = 0;
virtual bool is_fixed(expr* e, expr_ref& value) { return false; }
virtual void initialize() = 0;
virtual void start_propagation() {};
virtual bool propagate() = 0;
@ -192,6 +193,7 @@ namespace sls {
// Between plugin solvers
expr_ref get_value(expr* e);
bool is_fixed(expr* v, expr_ref& value);
bool set_value(expr* e, expr* v);
void new_value_eh(expr* e);
bool is_true(expr* e);

87
src/ast/sls/sls_seq_plugin.cpp
View file

@ -63,7 +63,7 @@ Alternate to lookahead strategy:
- create a priority buffer array of vector<ptr_vector<expr>> based on depth.
- walk from lowest depth up. Reset each inner buffer when processed. Parents always
have higher depth.
- calculate repair/break score when hitting a predicate based on bval1.
- calculate repair/break depth when hitting a predicate based on bval1.
- strval1 and bval1 are modified by
- use a global timestamp.
- label each eval subterm by a timestamp that gets set.
@ -145,9 +145,26 @@ namespace sls {
auto ve = ctx.get_value(e);
if (a.is_numeral(ve, r) && r == sx.length())
continue;
update(e, rational(sx.length()));
// set e to length of x or
// set x to a string of length e
if (r == 0 || sx.length() == 0) {
verbose_stream() << "todo-create lemma: len(x) = 0 <=> x = \"\"\n";
// create a lemma: len(x) = 0 => x = ""
}
if (ctx.rand(2) == 0 && update(e, rational(sx.length())))
return false;
if (r < sx.length() && update(x, sx.extract(0, r.get_unsigned())))
return false;
if (update(e, rational(sx.length())))
return false;
if (r > sx.length() && update(x, sx + zstring(m_chars[ctx.rand(m_chars.size())])))
return false;
verbose_stream() << mk_pp(x, m) << " = " << sx << " " << ve << "\n";
NOT_IMPLEMENTED_YET();
return false;
}
if ((seq.str.is_index(e, x, y, z) || seq.str.is_index(e, x, y)) && seq.is_string(x->get_sort())) {
auto sx = strval0(x);
auto sy = strval0(y);
@ -603,21 +620,32 @@ namespace sls {
auto const& R = rhs(eq);
unsigned i = 0, j = 0; // position into current string
unsigned ni = 0, nj = 0; // current string in concatenation
double depth = 1.0; // priority of update. Doubled when depth of equal strings are increased.
double score = 1.0; // priority of update. Doubled when score of equal strings are increased.
IF_VERBOSE(4,
verbose_stream() << "unify: \"" << strval0(eq->get_arg(0)) << "\" == \"" << strval0(eq->get_arg(1)) << "\"\n";
for (auto x : L) verbose_stream() << mk_pp(x, m) << " ";
verbose_stream() << " == ";
for (auto x : R) verbose_stream() << mk_pp(x, m) << " ";
verbose_stream() << "\n";
for (auto x : L) verbose_stream() << "\"" << strval0(x) << "\" ";
verbose_stream() << " == ";
for (auto x : R) verbose_stream() << "\"" << strval0(x) << "\" ";
verbose_stream() << "\n";
);
while (ni < L.size() && nj < R.size()) {
auto const& xi = L[ni];
auto const& yj = R[nj];
auto const& vi = strval0(xi);
auto const& vj = strval0(yj);
IF_VERBOSE(4,
verbose_stream() << "unify: \"" << vi << "\" = \"" << vj << "\" incides " << i << " " << j << "\n";
verbose_stream() << vi.length() << " " << vj.length() << "\n");
if (vi.length() == i && vj.length() == j) {
depth *= 2;
score *= 2;
if (nj + 1 < R.size() && !strval0(R[nj + 1]).empty())
m_str_updates.push_back({ xi, vi + zstring(strval0(R[nj + 1])[0]), depth });
m_str_updates.push_back({ xi, vi + zstring(strval0(R[nj + 1])[0]), score });
if (ni + 1 < L.size() && !strval0(L[ni + 1]).empty())
m_str_updates.push_back({ yj, vj + zstring(strval0(L[ni + 1])[0]), depth });
m_str_updates.push_back({ yj, vj + zstring(strval0(L[ni + 1])[0]), score });
i = 0;
j = 0;
++ni;
@ -627,8 +655,8 @@ namespace sls {
if (vi.length() == i) {
// xi -> vi + vj[j]
SASSERT(j < vj.length());
m_str_updates.push_back({ xi, vi + zstring(vj[j]), depth});
depth *= 2;
m_str_updates.push_back({ xi, vi + zstring(vj[j]), score});
score *= 2;
i = 0;
++ni;
continue;
@ -636,8 +664,8 @@ namespace sls {
if (vj.length() == j) {
// yj -> vj + vi[i]
SASSERT(i < vi.length());
m_str_updates.push_back({ yj, vj + zstring(vi[i]), depth });
depth *= 2;
m_str_updates.push_back({ yj, vj + zstring(vi[i]), score });
score *= 2;
j = 0;
++nj;
continue;
@ -645,30 +673,33 @@ namespace sls {
SASSERT(i < vi.length());
SASSERT(j < vj.length());
if (is_value(xi) && is_value(yj)) {
if (vi[i] != vj[j])
score = 1;
++i, ++j;
continue;
}
if (vi[i] == vj[j]) {
++i, ++j;
continue;
}
if (!is_value(xi)) {
m_str_updates.push_back({ xi, vi.extract(0, i), depth });
m_str_updates.push_back({ xi, vi.extract(0, i) + zstring(vj[j]), depth});
m_str_updates.push_back({ xi, vi.extract(0, i), score });
m_str_updates.push_back({ xi, vi.extract(0, i) + zstring(vj[j]), score});
}
if (!is_value(yj)) {
m_str_updates.push_back({ yj, vj.extract(0, j), depth });
m_str_updates.push_back({ yj, vj.extract(0, j) + zstring(vi[i]), depth });
m_str_updates.push_back({ yj, vj.extract(0, j), score });
m_str_updates.push_back({ yj, vj.extract(0, j) + zstring(vi[i]), score });
}
break;
}
for (; ni < L.size(); ++ni)
if (!is_value(L[ni]))
m_str_updates.push_back({ L[ni], zstring(), depth });
if (!is_value(L[ni]) && !strval0(L[ni]).empty())
m_str_updates.push_back({ L[ni], zstring(), 1 });
for (; nj < R.size(); ++nj)
if (!is_value(R[nj]))
m_str_updates.push_back({ R[nj], zstring(), depth });
if (!is_value(R[nj]) && !strval0(R[nj]).empty())
m_str_updates.push_back({ R[nj], zstring(), 1 });
return apply_update();
}
@ -1092,6 +1123,13 @@ namespace sls {
sum_scores += score;
for (auto const& [e, val, score] : m_int_updates)
sum_scores += score;
IF_VERBOSE(4,
for (auto const& [e, val, score] : m_str_updates)
verbose_stream() << mk_pp(e, m) << " := \"" << val << "\" score: " << score << "\n";
for (auto const& [e, val, score] : m_int_updates)
verbose_stream() << mk_pp(e, m) << " := " << val << " score: " << score << "\n";
);
while (!m_str_updates.empty() || !m_int_updates.empty()) {
bool is_str_update = false;
@ -1165,6 +1203,7 @@ namespace sls {
if (m_initialized)
return;
m_initialized = true;
expr_ref val(m);
for (auto lit : ctx.unit_literals()) {
auto e = ctx.atom(lit.var());
expr* x, * y, * z;
@ -1214,6 +1253,12 @@ namespace sls {
if (len_r.is_unsigned())
ev.max_length = std::min(ev.max_length, len_r.get_unsigned());
}
// TBD: assumes arithmetic is already initialized
if (seq.str.is_length(t, x) && ctx.is_fixed(t, val) &&
a.is_numeral(val, len_r) && len_r.is_unsigned()) {
auto& ev = get_eval(x);
ev.min_length = ev.max_length = len_r.get_unsigned();
}
}
}

4
src/tactic/sls/sls_tactic.cpp
View file

@ -78,7 +78,8 @@ public:
try {
res = m_sls->check();
}
catch (z3_exception&) {
catch (z3_exception& ex) {
IF_VERBOSE(1, verbose_stream() << "SLS threw an exception: " << ex.what() << "\n");
m_sls->collect_statistics(m_st);
throw;
}
@ -98,7 +99,6 @@ public:
}
else
mc = nullptr;
}
void operator()(goal_ref const& g,