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Better comments for SMT generation

main
Matthias Volk 8 years ago
parent
8051912147
commit
34911003e0
1 changed files with 51 additions and 14 deletions
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  1. 65
      src/storm-dft/modelchecker/dft/DFTASFChecker.cpp

65
src/storm-dft/modelchecker/dft/DFTASFChecker.cpp
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@ -271,7 +271,8 @@ namespace storm {
void DFTASFChecker::convert() {
std::vector<uint64_t> beVariables;
// Convert all elements
// Initialize variables
for (size_t i = 0; i < dft.nrElements(); ++i) {
std::shared_ptr<storm::storage::DFTElement<ValueType> const> element = dft.getElement(i);
varNames.push_back("t_" + element->name());
@ -294,21 +295,28 @@ namespace storm {
}
}
// BE
// Generate constraints
// No two BEs fail at the same time (first part of constraint 12)
constraints.push_back(std::make_shared<PairwiseDifferent>(beVariables));
constraints.back()->setDescription("No two BEs fail at the same time");
// All BEs have to fail (second part of constraint 12)
for (auto const& beV : beVariables) {
constraints.push_back(std::make_shared<BetweenValues>(beV, 1, dft.nrBasicElements()));
}
// Claim variables
for (auto const& csvV : claimVariables) {
constraints.push_back(std::make_shared<BetweenValues>(csvV.second, 0, dft.nrBasicElements() + 1));
// Initialize claim variables in [1, |BE|+1]
for (auto const& claimVariable : claimVariables) {
constraints.push_back(std::make_shared<BetweenValues>(claimVariable.second, 0, dft.nrBasicElements() + 1));
}
// First child of each spare is claimed in the beginning
for (size_t i = 0; i < dft.nrElements(); ++i) {
std::shared_ptr<storm::storage::DFTElement<ValueType> const> element = dft.getElement(i);
if(element->isSpareGate()) {
if (element->isSpareGate()) {
auto spare = std::static_pointer_cast<storm::storage::DFTSpare<double> const>(element);
auto const& spareChild = spare->children().front();
constraints.push_back(std::make_shared<IsConstantValue>(getClaimVariableIndex(spare->id(), spareChild->id()), 0));
@ -317,7 +325,9 @@ namespace storm {
}
}
// Encoding for specific gates
for (size_t i = 0; i < dft.nrElements(); ++i) {
// Get indices for gate children
std::vector<uint64_t> childVarIndices;
if (dft.isGate(i)) {
std::shared_ptr<storm::storage::DFTGate<ValueType> const> gate = dft.getGate(i);
@ -328,25 +338,39 @@ namespace storm {
std::shared_ptr<storm::storage::DFTElement<ValueType> const> element = dft.getElement(i);
switch (element->type()) {
case storm::storage::DFTElementType::BE:
// BEs were already considered before
break;
case storm::storage::DFTElementType::AND:
// Constraint for AND gate (constraint 1)
constraints.push_back(std::make_shared<IsMaximum>(timePointVariables.at(i), childVarIndices));
constraints.back()->setDescription("And gate");
break;
case storm::storage::DFTElementType::OR:
// Constraint for OR gate (constraint 2)
constraints.push_back(std::make_shared<IsMinimum>(timePointVariables.at(i), childVarIndices));
constraints.back()->setDescription("Or gate");
break;
case storm::storage::DFTElementType::PAND:
constraints.push_back(std::make_shared<IfThenElse>(std::make_shared<Sorted>(childVarIndices), std::make_shared<IsEqual>(timePointVariables.at(i), timePointVariables.at(childVarIndices.back())), std::make_shared<IsConstantValue>(timePointVariables.at(i), dft.nrBasicElements()+1)));
{
// Constraint for PAND gate (constraint 3)
std::shared_ptr<DFTConstraint> ifC = std::make_shared<Sorted>(childVarIndices);
std::shared_ptr<DFTConstraint> thenC = std::make_shared<IsEqual>(timePointVariables.at(i), timePointVariables.at(childVarIndices.back()));
std::shared_ptr<DFTConstraint> elseC = std::make_shared<IsConstantValue>(timePointVariables.at(i), dft.nrBasicElements()+1);
constraints.push_back(std::make_shared<IfThenElse>(ifC, thenC, elseC));
constraints.back()->setDescription("Pand gate");
}
case storm::storage::DFTElementType::SPARE:
{
auto spare = std::static_pointer_cast<storm::storage::DFTSpare<double> const>(element);
auto const& children = spare->children();
constraints.push_back(std::make_shared<Iff>(std::make_shared<IsLEqual>(getClaimVariableIndex(spare->id(), children.back()->id()), childVarIndices.back()), std::make_shared<IsEqual>(timePointVariables.at(i), childVarIndices.back())));
// If last child is claimed before failure the spare fails when the last child fails (constraint 5)
std::shared_ptr<DFTConstraint> leftC = std::make_shared<IsLEqual>(getClaimVariableIndex(spare->id(), children.back()->id()), childVarIndices.back());
constraints.push_back(std::make_shared<Iff>(leftC, std::make_shared<IsEqual>(timePointVariables.at(i), childVarIndices.back())));
constraints.back()->setDescription("Last child & claimed -> spare fails");
// Construct constraint for claiming
std::shared_ptr<DFTConstraint> elseCase = nullptr;
for (uint64_t j = 0; j < children.size(); ++j) {
uint64_t currChild = children.size() - 2 - j;
@ -354,22 +378,35 @@ namespace storm {
uint64_t xv = childVarIndices.at(currChild); // if v is the child, xv is the time x fails.
uint64_t csn = getClaimVariableIndex(spare->id(), childVarIndices.at(currChild+1)); // csn is the moment the spare claims the next child
uint64_t xn = childVarIndices.at(currChild+1); // xn is the moment the next child fails
// Generate constraint for trying to claim next child
if (j == 0) {
elseCase = std::make_shared<IsEqual>(timePointVariables.at(i), xv);
// Last child: spare fails at same point as xv (otherwise case in constraint 7)
elseCase = std::make_shared<IsEqual>(timePointVariables.at(i), xv);
}
// Next child is not yet failed
ifcs.push_back(std::make_shared<IsLEqual>(xv, xn));
// Child is not yet claimed by a different spare (first part of case distinction for constraint 7)
for (auto const& otherSpare : children.at(currChild+1)->parents()) {
if (otherSpare->id() == i) { continue; }// not a OTHER spare.
if (otherSpare->id() == i) {
// not an OTHER spare.
continue;
}
ifcs.push_back(std::make_shared<IsConstantValue>(getClaimVariableIndex(otherSpare->id(), children.at(currChild+1)->id()), dft.nrBasicElements()+1));
}
std::shared_ptr<DFTConstraint> ite = std::make_shared<IfThenElse>(std::make_shared<And>(ifcs), std::make_shared<IsEqual>(csn, xv), elseCase);
elseCase = ite;
constraints.push_back(std::make_shared<Iff>(std::make_shared<IsLEqual>(getClaimVariableIndex(spare->id(), children.at(currChild)->id()), xv), ite));
// Claim next child (constraint 7)
// elseCase contains the constraints for the recursive call to phi^s_{i+1}
std::shared_ptr<DFTConstraint> tryClaimC = std::make_shared<IfThenElse>(std::make_shared<And>(ifcs), std::make_shared<IsEqual>(csn, xv), elseCase);
elseCase = tryClaimC;
// If i-th child fails after being claimed, then try to claim (i+1)-th child (constraint 6)
constraints.push_back(std::make_shared<Iff>(std::make_shared<IsLEqual>(getClaimVariableIndex(spare->id(), children.at(currChild)->id()), xv), tryClaimC));
constraints.back()->setDescription(std::to_string(j+1) + " but last child & claimed");
}
break;
}
default:
STORM_LOG_WARN("DFT element of type '" << element->type() << "' is ignored for SMT encoding.");
break;
}
}

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