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pb theory

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2013-11-16 21:05:33 -08:00
parent 77cdb2bcde
commit f6c5088cc9
3 changed files with 112 additions and 34 deletions
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1
src/smt/tactic/smt_tactic.cpp
View file

@ -135,7 +135,6 @@ public:
proof_converter_ref & pc,
expr_dependency_ref & core) {
try {
IF_VERBOSE(0, verbose_stream() << "(smt.smt-tactic using the old SAT solver)\n";);
SASSERT(in->is_well_sorted());
ast_manager & m = in->m();
TRACE("smt_tactic", tout << this << "\nAUTO_CONFIG: " << fparams().m_auto_config << " HIDIV0: " << fparams().m_hi_div0 << " "

140
src/smt/theory_pb.cpp
View file

@ -52,6 +52,7 @@ namespace smt {
SASSERT(!ctx.b_internalized(atom));
bool_var abv = ctx.mk_bool_var(atom);
ctx.set_var_theory(abv, get_id());
ineq* c = alloc(ineq, atom, literal(abv));
c->m_k = m_util.get_k(atom);
@ -119,7 +120,7 @@ namespace smt {
n *= 2;
}
c->m_compilation_threshold = args.size()*log;
TRACE("card", tout << "threshold:" << (args.size()*log) << "\n";);
TRACE("card", tout << "compilation threshold: " << (args.size()*log) << "\n";);
}
else {
c->m_compilation_threshold = UINT_MAX;
@ -364,19 +365,22 @@ namespace smt {
void theory_pb::assign_eh(bool_var v, bool is_true) {
context& ctx = get_context();
ast_manager& m = get_manager();
ptr_vector<ineq>* ineqs = 0;
ineq* c = 0;
TRACE("card", tout << "assign: " << mk_pp(ctx.bool_var2expr(v), m) << " <- " << is_true << "\n";);
TRACE("card", tout << "assign: " << literal(v, !is_true) << "\n";);
if (m_watch.find(v, ineqs)) {
for (unsigned i = 0; i < ineqs->size(); ++i) {
assign_watch(v, is_true, *ineqs, i);
if (assign_watch(v, is_true, *ineqs, i)) {
// i was removed from watch list.
--i;
}
}
}
ineq* c = 0;
if (m_ineqs.find(v, c)) {
assign_ineq(*c);
assign_ineq(*c, is_true);
}
TRACE("card", display(tout););
}
literal_vector& theory_pb::get_helpful_literals(ineq& c, bool negate) {
@ -414,7 +418,8 @@ namespace smt {
on the assumption that inequalities are mostly units
and/or relatively few compared to number of argumets.
*/
void theory_pb::assign_ineq(ineq& c) {
void theory_pb::assign_ineq(ineq& c, bool is_true) {
context& ctx = get_context();
numeral sum = 0, maxsum = 0;
for (unsigned i = 0; i < c.size(); ++i) {
@ -430,13 +435,17 @@ namespace smt {
}
}
lbool lit_assignment = ctx.get_assignment(c.lit());
SASSERT(lit_assignment != l_undef);
if (sum >= c.k() && lit_assignment == l_false) {
TRACE("card",
tout << "assign: " << c.lit() << " <- " << is_true << "\n";
display(tout, c); );
if (sum >= c.k() && !is_true) {
literal_vector& lits = get_helpful_literals(c, true);
lits.push_back(c.lit());
add_clause(c, lits);
}
else if (maxsum < c.k() && lit_assignment == l_true) {
else if (maxsum < c.k() && is_true) {
literal_vector& lits = get_unhelpful_literals(c, true);
lits.push_back(~c.lit());
add_clause(c, lits);
@ -450,21 +459,25 @@ namespace smt {
(inequalities are closed under negation).
*/
void theory_pb::assign_watch(bool_var v, bool is_true, watch_list& watch, unsigned watch_index) {
bool theory_pb::assign_watch(bool_var v, bool is_true, watch_list& watch, unsigned watch_index) {
bool removed = false;
context& ctx = get_context();
ineq& c = *watch[watch_index];
numeral k = c.m_k;
unsigned w = c.find_lit(v, 0, c.watch_size());
numeral coeff = c.coeff(w);
TRACE("card",
tout << "assign: " << literal(v) << " <- " << is_true << "\n";
display(tout, c); );
if (is_true == c.lit(w).sign()) {
//
// sum is not increased.
// Adjust set of watched literals.
//
del_watch(watch, watch_index, c, w);
numeral tmp_sum = c.sum();
for (unsigned i = c.watch_size(); c.max_sum() - coeff < k + c.max_coeff() && i < c.size(); ++i) {
for (unsigned i = c.watch_size(); c.max_sum() < k + c.max_coeff() + coeff && i < c.size(); ++i) {
lbool lit_assignment = ctx.get_assignment(c.lit(i));
switch(lit_assignment) {
case l_true:
@ -477,19 +490,17 @@ namespace smt {
break;
}
}
if (c.max_sum() >= k + coeff) {
del_watch(watch, watch_index, c, w);
SASSERT(c.max_sum() >= k);
removed = true;
}
SASSERT(tmp_sum <= c.max_sum());
TRACE("card", tout << "tmp_sum: " << tmp_sum << "\n"; display(tout, c); );
if (c.max_sum() < k) {
//
// c.lit() <- false
// we have to add the previously watched literal back.
// such that the sum of watched literals has maximal sum >= k
//
SASSERT(coeff == c.coeff(w));
SASSERT(c.max_sum() + coeff >= k);
add_watch(c, c.find_lit(v, c.watch_size(), c.size()));
SASSERT(c.max_sum() >= k);
switch(ctx.get_assignment(c.lit())) {
case l_false:
break;
@ -506,24 +517,44 @@ namespace smt {
}
}
else if (tmp_sum >= k) {
// ineq should be true.
// this is handled below
//
// c.lit() <- true
//
switch(ctx.get_assignment(c.lit())) {
case l_true:
break;
case l_false: {
literal_vector& lits = get_helpful_literals(c, true);
lits.push_back(c.lit());
add_clause(c, lits);
break;
}
case l_undef: {
add_assign(c, get_helpful_literals(c, false), c.lit());
break;
}
}
}
else if (c.max_sum() - c.max_coeff() < k) {
else if (c.max_sum() < k + c.max_coeff()) {
// tmp_sum < k <= c.max_sum()
// opportunities for unit propagation for unassigned
// literals whose coefficients satisfy
// c.max_sum() - coeff < k
if (l_true == ctx.get_assignment(c.lit())) {
literal_vector& lits = get_unhelpful_literals(c, false);
literal_vector& lits = get_unhelpful_literals(c, true);
lits.push_back(c.lit());
numeral max_sum = c.max_sum() - coeff;
for (unsigned i = 0; i < c.size(); ++i) {
if (c.max_sum() - c.coeff(i) < k && ctx.get_assignment(c.lit(i)) == l_undef) {
if (max_sum - c.coeff(i) < k && ctx.get_assignment(c.lit(i)) == l_undef) {
add_assign(c, lits, c.lit(i));
}
}
}
}
else {
// c.max_sum() >= k + c.max_coeff()
// tmp_sum < k <= c.max_sum() - c.max_coeff()
// we might miss opportunities for unit propagation if
// max_coeff is not the maximal coefficient
@ -562,7 +593,8 @@ namespace smt {
// Progress was made.
// The watch list contains at least enough
// literals to force the assignment.
return removed;
}
struct theory_pb::sort_expr {
@ -759,13 +791,45 @@ namespace smt {
void theory_pb::pop_scope_eh(unsigned num_scopes) {
unsigned sz = m_ineqs_lim[m_ineqs_lim.size()-num_scopes];
while (m_ineqs_trail.size() > sz) {
SASSERT(m_ineqs.contains(m_ineqs_trail.back()));
m_ineqs.remove(m_ineqs_trail.back());
m_ineqs_trail.pop_back();
bool_var v = m_ineqs_trail.back();
ineq* c = 0;
VERIFY(m_ineqs.find(v, c));
m_ineqs.remove(v);
m_ineqs_trail.pop_back();
for (unsigned i = 0; i < c->watch_size(); ++i) {
bool_var w = c->lit(i).var();
ptr_vector<ineq>* ineqs = 0;
VERIFY(m_watch.find(w, ineqs));
for (unsigned j = 0; j < ineqs->size(); ++j) {
if ((*ineqs)[j] == c) {
std::swap((*ineqs)[j],(*ineqs)[ineqs->size()-1]);
ineqs->pop_back();
break;
}
}
}
dealloc(c);
}
m_ineqs_lim.resize(m_ineqs_lim.size()-num_scopes);
}
void theory_pb::display(std::ostream& out) const {
u_map<ptr_vector<ineq>*>::iterator it = m_watch.begin(), end = m_watch.end();
for (; it != end; ++it) {
out << "watch: " << literal(it->m_key) << " |-> ";
watch_list const& wl = *it->m_value;
for (unsigned i = 0; i < wl.size(); ++i) {
out << wl[i]->lit() << " ";
}
out << "\n";
}
u_map<ineq*>::iterator itc = m_ineqs.begin(), endc = m_ineqs.end();
for (; itc != endc; ++itc) {
ineq& c = *itc->m_value;
display(out, c);
}
}
std::ostream& theory_pb::display(std::ostream& out, ineq& c) const {
ast_manager& m = get_manager();
out << mk_pp(c.m_app, m) << "\n";
@ -779,6 +843,8 @@ namespace smt {
<< "propagations: " << c.m_num_propagations
<< " max_coeff: " << c.max_coeff()
<< " watch size: " << c.watch_size()
<< " sum: " << c.sum()
<< " max-sum: " << c.max_sum()
<< "\n";
return out;
}
@ -793,6 +859,13 @@ namespace smt {
inc_propagations(c);
m_stats.m_num_propagations++;
context& ctx = get_context();
TRACE("card", tout << "#prop:" << c.m_num_propagations << " - ";
for (unsigned i = 0; i < lits.size(); ++i) {
tout << lits[i] << " ";
}
tout << "=> " << l << "\n";
display(tout, c););
ctx.assign(l, ctx.mk_justification(
theory_propagation_justification(
get_id(), ctx.get_region(), lits.size(), lits.c_ptr(), l)));
@ -804,7 +877,12 @@ namespace smt {
inc_propagations(c);
m_stats.m_num_axioms++;
context& ctx = get_context();
TRACE("card", tout << "#prop:" << c.m_num_propagations << " - "; ctx.display_literals_verbose(tout, lits.size(), lits.c_ptr()); tout << "\n";);
TRACE("card", tout << "#prop:" << c.m_num_propagations << " - ";
for (unsigned i = 0; i < lits.size(); ++i) {
tout << lits[i] << " ";
}
tout << "\n";
display(tout, c););
justification* js = 0;
ctx.mk_clause(lits.size(), lits.c_ptr(), js, CLS_AUX_LEMMA, 0);
IF_VERBOSE(2, ctx.display_literals_verbose(verbose_stream(),

5
src/smt/theory_pb.h
View file

@ -110,10 +110,11 @@ namespace smt {
literal compile_arg(expr* arg);
void add_watch(ineq& c, unsigned index);
void del_watch(watch_list& watch, unsigned index, ineq& c, unsigned ineq_index);
void assign_watch(bool_var v, bool is_true, watch_list& watch, unsigned index);
void assign_ineq(ineq& c);
bool assign_watch(bool_var v, bool is_true, watch_list& watch, unsigned index);
void assign_ineq(ineq& c, bool is_true);
std::ostream& display(std::ostream& out, ineq& c) const;
virtual void display(std::ostream& out) const;
void add_clause(ineq& c, literal_vector const& lits);
void add_assign(ineq& c, literal_vector const& lits, literal l);