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#include "theory/arith/difference_manager.h"
#include "theory/uf/equality_engine_impl.h"
#include "theory/arith/constraint.h"
#include "theory/arith/arith_utilities.h"
namespace CVC4 {
namespace theory {
namespace arith {
DifferenceManager::DifferenceManager(context::Context* c, ConstraintDatabase& cd, TNodeCallBack& setup)
: d_conflict(c),
d_literalsQueue(c),
d_propagatations(c),
d_explanationMap(c),
d_constraintDatabase(cd),
d_setupLiteral(setup),
d_notify(*this),
d_ee(d_notify, c, "theory::arith::DifferenceManager"),
d_false(NodeManager::currentNM()->mkConst<bool>(false)),
d_hasSharedTerms(c, false)
{}
void DifferenceManager::differenceIsZero(Constraint lb, Constraint ub){
Assert(lb->isLowerBound());
Assert(ub->isUpperBound());
Assert(lb->getVariable() == ub->getVariable());
Assert(lb->getValue().sgn() == 0);
Assert(ub->getValue().sgn() == 0);
ArithVar s = lb->getVariable();
Node reason = ConstraintValue::explainConflict(lb,ub);
assertLiteral(true, s, reason);
}
void DifferenceManager::differenceIsZero(Constraint eq){
Assert(eq->isEquality());
Assert(eq->getValue().sgn() == 0);
ArithVar s = eq->getVariable();
//Explain for conflict is correct as these proofs are generated and stored eagerly
//These will be safe for propagation later as well
Node reason = eq->explainForConflict();
assertLiteral(true, s, reason);
}
void DifferenceManager::differenceCannotBeZero(Constraint c){
ArithVar s = c->getVariable();
//Explain for conflict is correct as these proofs are generated and stored eagerly
//These will be safe for propagation later as well
Node reason = c->explainForConflict();
assertLiteral(false, s, reason);
}
bool DifferenceManager::propagate(TNode x){
Debug("arith::differenceManager")<< "DifferenceManager::propagate("<<x<<")"<<std::endl;
if(inConflict()){
return true;
}
Node rewritten = Rewriter::rewrite(x);
//Need to still propagate this!
if(rewritten.getKind() == kind::CONST_BOOLEAN){
pushBack(x);
}
Assert(rewritten.getKind() != kind::CONST_BOOLEAN);
Constraint c = d_constraintDatabase.lookup(rewritten);
if(c == NullConstraint){
//using setup as there may not be a corresponding difference literal yet
d_setupLiteral(rewritten);
c = d_constraintDatabase.lookup(rewritten);
Assert(c != NullConstraint);
//c = d_constraintDatabase.addLiteral(rewritten);
}
Debug("arith::differenceManager")<< "x is "
<< c->hasProof() << " "
<< (x == rewritten) << " "
<< c->canBePropagated() << " "
<< c->negationHasProof() << std::endl;
if(c->negationHasProof()){
Node expC = explainInternal(x);
Node neg = c->getNegation()->explainForConflict();
Node conf = expC.andNode(neg);
Node final = flattenAnd(conf);
d_conflict.set(final);
Debug("arith::differenceManager") << "differenceManager found a conflict " << final << std::endl;
return false;
}
// Cases for propagation
// C : c has a proof
// S : x == rewritten
// P : c can be propagated
//
// CSP
// 000 : propagate x, and mark C it as being explained
// 001 : propagate x, and propagate c after marking it as being explained
// 01* : propagate x, mark c but do not propagate c
// 10* : propagate x, do not mark c and do not propagate c
// 11* : drop the constraint, do not propagate x or c
if(!c->hasProof() && x != rewritten){
pushBack(x, rewritten);
c->setEqualityEngineProof();
if(c->canBePropagated() && !c->assertedToTheTheory()){
c->propagate();
}
}else if(!c->hasProof() && x == rewritten){
pushBack(x, rewritten);
c->setEqualityEngineProof();
}else if(c->hasProof() && x != rewritten){
pushBack(x, rewritten);
}else{
Assert(c->hasProof() && x == rewritten);
}
return true;
}
void DifferenceManager::explain(TNode literal, std::vector<TNode>& assumptions) {
TNode lhs, rhs;
switch (literal.getKind()) {
case kind::EQUAL:
lhs = literal[0];
rhs = literal[1];
break;
case kind::NOT:
lhs = literal[0];
rhs = d_false;
break;
default:
Unreachable();
}
d_ee.explainEquality(lhs, rhs, assumptions);
}
void DifferenceManager::enqueueIntoNB(const std::set<TNode> s, NodeBuilder<>& nb){
std::set<TNode>::const_iterator it = s.begin();
std::set<TNode>::const_iterator it_end = s.end();
for(; it != it_end; ++it) {
nb << *it;
}
}
Node DifferenceManager::explainInternal(TNode internal){
std::vector<TNode> assumptions;
explain(internal, assumptions);
std::set<TNode> assumptionSet;
assumptionSet.insert(assumptions.begin(), assumptions.end());
if (assumptionSet.size() == 1) {
// All the same, or just one
return assumptions[0];
}else{
NodeBuilder<> conjunction(kind::AND);
enqueueIntoNB(assumptionSet, conjunction);
return conjunction;
}
}
Node DifferenceManager::explain(TNode external){
Node internal = externalToInternal(external);
return explainInternal(internal);
}
void DifferenceManager::explain(TNode external, NodeBuilder<>& out){
Node internal = externalToInternal(external);
std::vector<TNode> assumptions;
explain(internal, assumptions);
std::set<TNode> assumptionSet;
assumptionSet.insert(assumptions.begin(), assumptions.end());
enqueueIntoNB(assumptionSet, out);
}
void DifferenceManager::addDifference(ArithVar s, Node x, Node y){
Assert(s >= d_differences.size() || !isDifferenceSlack(s));
Debug("arith::differenceManager") << s << x << y << std::endl;
d_differences.resize(s+1);
d_differences[s] = Difference(x,y);
}
void DifferenceManager::addAssertionToEqualityEngine(bool eq, ArithVar s, TNode reason){
Assert(isDifferenceSlack(s));
TNode x = d_differences[s].x;
TNode y = d_differences[s].y;
if(eq){
d_ee.addEquality(x, y, reason);
}else{
d_ee.addDisequality(x, y, reason);
}
}
void DifferenceManager::dequeueLiterals(){
Assert(d_hasSharedTerms);
while(!d_literalsQueue.empty() && !inConflict()){
const LiteralsQueueElem& front = d_literalsQueue.front();
d_literalsQueue.dequeue();
addAssertionToEqualityEngine(front.d_eq, front.d_var, front.d_reason);
}
}
void DifferenceManager::enableSharedTerms(){
Assert(!d_hasSharedTerms);
d_hasSharedTerms = true;
dequeueLiterals();
}
void DifferenceManager::assertLiteral(bool eq, ArithVar s, TNode reason){
d_literalsQueue.enqueue(LiteralsQueueElem(eq, s, reason));
if(d_hasSharedTerms){
dequeueLiterals();
}
}
void DifferenceManager::addSharedTerm(Node x){
if(!d_hasSharedTerms){
enableSharedTerms();
}
d_ee.addTriggerTerm(x);
}
}/* CVC4::theory::arith namespace */
}/* CVC4::theory namespace */
}/* CVC4 namespace */
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