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working on pb

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2013-11-18 22:41:06 -08:00
parent efecb9b6c0
commit 1a8ff9cea4
2 changed files with 101 additions and 31 deletions
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120
src/smt/theory_pb.cpp
View file

@ -66,6 +66,10 @@ namespace smt {
return a;
}
theory_pb::numeral theory_pb::ineq::lcm(numeral a, numeral b) {
return (a*b)/gcd(a,b);
}
lbool theory_pb::ineq::normalize() {
numeral& k = m_k;
@ -996,27 +1000,76 @@ namespace smt {
if (lvl == m_conflict_lvl) {
IF_VERBOSE(0, verbose_stream() << "new mark\n";);
++m_num_marks;
if (v >= static_cast<bool_var>(m_conseq_index.size())) {
m_conseq_index.resize(v+1);
}
m_conseq_index[v] = m_lemma_index;
}
}
m_lemma.m_args.push_back(std::make_pair(l, coeff));
SASSERT(m_lemma_index <= m_lemma.size());
if (m_lemma_index == m_lemma.size()) {
m_lemma.m_args.resize(m_lemma_index+1);
}
m_lemma.m_args[m_lemma_index] = std::make_pair(l, coeff);
m_lemma_index = m_lemma.size();
}
else if (ctx.get_assignment(l) == l_true) {
else if (ctx.get_assignment(l) != l_false) {
m_lemma.m_k += coeff;
}
}
void theory_pb::process_ineq(ineq& c) {
// TBD: create CUT.
// only process literals that were
void theory_pb::process_ineq(ineq& c, literal conseq, numeral coeff1) {
//
// Create CUT.
// TBD only process literals that were
// assigned below current index 'idx'.
// and/or relevant to the conflict.
//
//
// . find coeff2
// . find lcm of coefficients to conseq.
// . multiply m_lemma by lcm/coeff coefficient to align.
// . create lcm/coeff_2 to multiply on this side.
// . cut resolve constraints.
//
context& ctx = get_context();
numeral coeff2 = (conseq==null_literal)?1:0;
for (unsigned i = 0; i < c.size(); ++i) {
if (ctx.get_assignment(c.lit(i)) == l_false) {
process_antecedent(c.lit(i), c.coeff(i));
if (c.lit(i) == conseq) {
coeff2 = c.coeff(i);
break;
}
}
process_antecedent(~c.lit(), 1);
m_lemma.m_k += c.k();
SASSERT(coeff2 > 0);
numeral lc = ineq::lcm(coeff1, coeff2);
numeral g = lc/coeff1;
if (g > 1) {
for (unsigned i = 0; i < m_lemma.size(); ++i) {
m_lemma.m_args[i].second *= g;
}
m_lemma.m_k *= g;
}
g = lc/coeff2;
for (unsigned i = 0; i < c.size(); ++i) {
if (ctx.get_assignment(c.lit(i)) == l_false) {
process_antecedent(c.lit(i), g*c.coeff(i));
}
else if (conseq == c.lit(i)) {
// skip this one.
}
else {
m_lemma.m_k += g*c.coeff(i);
}
}
m_lemma.m_k += g*c.k();
//
// we most likely want c.lit() to be
// an antecedent in a real clause.
// process_antecedent(~c.lit(), 1);
//
}
//
@ -1029,48 +1082,60 @@ namespace smt {
bool_var v;
context& ctx = get_context();
unsigned& lvl = m_conflict_lvl = 0;
bool found = false;
unsigned conseq_index = 0;
for (unsigned i = 0; i < c.size(); ++i) {
if (ctx.get_assignment(c.lit(i)) == l_false) {
lvl = std::max(lvl, ctx.get_assign_level(c.lit(i)));
}
found = found || (~conseq == c.lit(i));
if (~conseq == c.lit(i)) {
conseq_index = i;
}
}
SASSERT(lvl >= ctx.get_assign_level(c.lit()));
SASSERT(ctx.get_assignment(conseq) == l_true);
SASSERT(found); // conseq is negative in c
SASSERT(conseq_index > 0 || ~conseq == c.lit(0)); // conseq is negative in c
if (lvl == ctx.get_base_level()) {
return;
}
b_justification js(ctx.mk_justification(
pb_justification(
c, get_id(), ctx.get_region(),
0, 0, c.lit())));
m_lemma.reset();
m_num_marks = 0;
m_lemma.reset();
m_lemma_index = 0;
process_ineq(c, null_literal, 1); // add consequent to lemma.
SASSERT(c.lit(conseq_index) == ~conseq);
// point into stack of assigned literals
literal_vector const& lits = ctx.assigned_literals();
SASSERT(!lits.empty());
unsigned idx = lits.size()-1;
b_justification js = ctx.get_justification(conseq.var());
do {
//
// Resolve selected conseq with antecedents.
//
IF_VERBOSE(0, verbose_stream() << conseq << " " << js.get_kind() << "\n";);
numeral conseq_coeff = m_lemma.coeff(conseq_index);
m_lemma_index = conseq_index;
switch(js.get_kind()) {
case b_justification::CLAUSE: {
clause& cls = *js.get_clause();
unsigned num_lits = cls.get_num_literals();
for (unsigned i = 0; i < num_lits; ++i) {
process_antecedent(cls.get_literal(i), 1);
if (cls.get_literal(0) == conseq) {
process_antecedent(cls.get_literal(1), conseq_coeff);
}
m_lemma.m_k += 1;
else {
SASSERT(cls.get_literal(1) == conseq);
process_antecedent(cls.get_literal(0), conseq_coeff);
}
for (unsigned i = 2; i < num_lits; ++i) {
process_antecedent(cls.get_literal(i), conseq_coeff);
}
m_lemma.m_k += conseq_coeff;
justification* cjs = cls.get_justification();
if (cjs) {
// TBD
@ -1079,9 +1144,8 @@ namespace smt {
break;
}
case b_justification::BIN_CLAUSE:
m_lemma.m_k += 1;
process_antecedent(conseq, 1);
process_antecedent(~js.get_literal(), 1);
m_lemma.m_k += conseq_coeff;
process_antecedent(~js.get_literal(), conseq_coeff);
break;
case b_justification::AXIOM:
break;
@ -1091,12 +1155,13 @@ namespace smt {
if (j.get_from_theory() != get_id()) break;
pb_justification& pbj = dynamic_cast<pb_justification&>(j);
// weaken the lemma and resolve.
process_ineq(pbj.get_ineq());
process_ineq(pbj.get_ineq(), conseq, conseq_coeff);
break;
}
default:
UNREACHABLE();
}
m_lemma.normalize();
//
// find the next marked variable in the assignment stack
//
@ -1109,7 +1174,9 @@ namespace smt {
}
while (!ctx.is_marked(v));
js = ctx.get_justification(v);
conseq_index = m_conseq_index[v];
js = ctx.get_justification(v);
--m_num_marks;
}
while (m_num_marks > 0);
@ -1120,7 +1187,6 @@ namespace smt {
m_unmark.pop_back();
}
TRACE("pb", display(tout, m_lemma););
IF_VERBOSE(1, display(verbose_stream(), m_lemma););

12
src/smt/theory_pb.h
View file

@ -93,6 +93,7 @@ namespace smt {
bool well_formed() const;
static numeral gcd(numeral a, numeral b);
static numeral lcm(numeral a, numeral b);
};
@ -137,13 +138,16 @@ namespace smt {
//
// Conflict resolution, cutting plane derivation.
//
unsigned m_num_marks;
unsigned m_conflict_lvl;
ineq m_lemma;
unsigned m_num_marks;
unsigned m_conflict_lvl;
ineq m_lemma;
unsigned_vector m_conseq_index;
unsigned m_lemma_index;
svector<bool_var> m_unmark;
void set_next_index(unsigned i);
void resolve_conflict(literal conseq, ineq& c);
void process_antecedent(literal l, numeral coeff);
void process_ineq(ineq& c);
void process_ineq(ineq& c, literal conseq, numeral coeff);
void validate_final_check();
void validate_final_check(ineq& c);