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advanced stopping criteria for multi-counterexamples, additional measurements for cuts, an option to properly disable backward implications, and some cleaning

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Sebastian Junges 7 years ago
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1 changed files with 128 additions and 87 deletions
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  1. 75
      src/storm-counterexamples/counterexamples/SMTMinimalLabelSetGenerator.h

75
src/storm-counterexamples/counterexamples/SMTMinimalLabelSetGenerator.h
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@ -29,6 +29,19 @@ namespace storm {
namespace counterexamples {
/**
* Helper to avoid case disticinot between prism and jani
* Returns the number of edges/commands in a symbolic model description.
*/
size_t nrCommands(storm::storage::SymbolicModelDescription const& descr) {
if (descr.isJaniModel()) {
return descr.asJaniModel().getNumberOfEdges();
} else {
assert(descr.isPrismModel());
return descr.asPrismProgram().getNumberOfCommands();
}
}
/*!
* This class provides functionality to generate a minimal counterexample to a probabilistic reachability
* property in terms of used labels.
@ -313,12 +326,18 @@ namespace storm {
* @param context The Z3 context in which to build the expressions.
* @param solver The solver to use for the satisfiability evaluation.
*/
static void assertCuts(storm::storage::SymbolicModelDescription const& symbolicModel, storm::models::sparse::Model<T> const& model, std::vector<boost::container::flat_set<uint_fast64_t>> const& labelSets, storm::storage::BitVector const& psiStates, VariableInformation const& variableInformation, RelevancyInformation const& relevancyInformation, storm::solver::SmtSolver& solver) {
static std::chrono::milliseconds assertCuts(storm::storage::SymbolicModelDescription const& symbolicModel, storm::models::sparse::Model<T> const& model, std::vector<boost::container::flat_set<uint_fast64_t>> const& labelSets, storm::storage::BitVector const& psiStates, VariableInformation const& variableInformation, RelevancyInformation const& relevancyInformation, storm::solver::SmtSolver& solver, bool addBackwardImplications) {
// Walk through the model and
// * identify labels enabled in initial states
// * identify labels that can directly precede a given action
// * identify labels that directly reach a target state
// * identify labels that can directly follow a given action
auto assertCutsClock = std::chrono::high_resolution_clock::now();
//
if (addBackwardImplications) {
STORM_LOG_THROW(!symbolicModel.isJaniModel() || !symbolicModel.asJaniModel().usesAssignmentLevels(), storm::exceptions::NotSupportedException, "Counterexample generation with backward implications is not supported for indexed assignments");
}
boost::container::flat_set<uint_fast64_t> initialLabels;
std::set<boost::container::flat_set<uint_fast64_t>> initialCombinations;
@ -334,6 +353,7 @@ namespace storm {
storm::storage::BitVector const& initialStates = model.getInitialStates();
for (auto currentState : relevancyInformation.relevantStates) {
bool isInitial = initialStates.get(currentState);
for (auto currentChoice : relevancyInformation.relevantChoicesForRelevantStates.at(currentState)) {
// If the choice is a synchronization choice, we need to record it.
@ -344,7 +364,7 @@ namespace storm {
}
// If the state is initial, we need to add all the choice labels to the initial label set.
if (initialStates.get(currentState)) {
if (isInitial) {
initialLabels.insert(labelSets[currentChoice].begin(), labelSets[currentChoice].end());
initialCombinations.insert(labelSets[currentChoice]);
}
@ -378,6 +398,7 @@ namespace storm {
for (auto const& successorEntry : transitionMatrix.getRow(predecessorChoice)) {
if (successorEntry.getColumn() == currentState) {
choiceTargetsCurrentState = true;
break;
}
}
@ -392,8 +413,7 @@ namespace storm {
// Store the found implications in a container similar to the preceding label sets.
std::map<boost::container::flat_set<uint_fast64_t>, std::set<boost::container::flat_set<uint_fast64_t>>> backwardImplications;
if (!symbolicModel.isJaniModel() || !symbolicModel.asJaniModel().usesAssignmentLevels()) {
if (addBackwardImplications) {
// Create a new solver over the same variables as the given symbolic model description to use it for
// determining the symbolic cuts.
std::unique_ptr<storm::solver::SmtSolver> localSolver;
@ -587,8 +607,7 @@ namespace storm {
// Iterate over all possible combinations of updates of the preceding command set.
std::vector<storm::expressions::Expression> formulae;
bool done = false;
while (!done) {
while (true) {
std::map<storm::expressions::Variable, storm::expressions::Expression> currentVariableUpdateCombinationMap;
for (auto const& updateIterator : iteratorVector) {
for (auto const& variableUpdatePair : *updateIterator) {
@ -616,7 +635,7 @@ namespace storm {
// If we had to reset all iterator to the start, we are done.
if (k == 0) {
done = true;
break;
}
}
@ -723,6 +742,8 @@ namespace storm {
}
}
if(addBackwardImplications) {
STORM_LOG_DEBUG("Asserting taken labels are followed and preceeded by another label if they are not a target label or an initial label, respectively.");
boost::container::flat_map<boost::container::flat_set<uint_fast64_t>, storm::expressions::Expression> labelSetToFormula;
for (auto const &labelSet : relevancyInformation.relevantLabelSets) {
@ -802,6 +823,7 @@ namespace storm {
for (auto const &labelSetFormula : labelSetToFormula) {
solver.add(labelSetFormula.second || getOtherSynchronizationEnabledFormula(labelSetFormula.first, synchronizingLabels, labelSetToFormula, variableInformation, relevancyInformation));
}
}
STORM_LOG_DEBUG("Asserting synchronization cuts.");
// Finally, assert that if we take one of the synchronizing labels, we also take one of the combinations
@ -837,6 +859,9 @@ namespace storm {
assertDisjunction(solver, formulae, *variableInformation.manager);
}
}
auto endTime = std::chrono::high_resolution_clock::now();
return std::chrono::duration_cast<std::chrono::milliseconds>(endTime - assertCutsClock);
}
/*!
@ -1022,9 +1047,11 @@ namespace storm {
static std::vector<std::vector<storm::expressions::Expression>> createAdderPairs(VariableInformation const& variableInformation, std::vector<std::vector<storm::expressions::Expression>> const& in) {
std::vector<std::vector<storm::expressions::Expression>> result;
result.reserve(in.size() / 2 + in.size() % 2);
for (uint_fast64_t index = 0; index < in.size() / 2; ++index) {
uint64_t maxIndex = in.size() / 2;
result.reserve(maxIndex + in.size() % 2);
for (uint_fast64_t index = 0; index < maxIndex; ++index) {
result.push_back(createAdder(variableInformation, in[2 * index], in[2 * index + 1]));
}
@ -1586,9 +1613,11 @@ namespace storm {
bool encodeReachability;
bool useDynamicConstraints;
bool silent = false;
bool addBackwardImplicationCuts = true;
uint64_t continueAfterFirstCounterexampleUntil = 0;
uint64_t maximumCounterexamples = 1;
uint64_t multipleCounterexampleSizeCap = 100000000;
uint64_t maximumExtraIterations = 100000000;
};
struct GeneratorStats {
@ -1596,8 +1625,11 @@ namespace storm {
std::chrono::milliseconds solverTime;
std::chrono::milliseconds modelCheckingTime;
std::chrono::milliseconds analysisTime;
std::chrono::milliseconds cutTime;
uint64_t iterations;
};
/*!
* Computes the minimal command set that is needed in the given model to exceed the given probability threshold for satisfying phi until psi.
*
@ -1680,18 +1712,18 @@ namespace storm {
variableInformation.adderVariables = assertAdder(*solver, variableInformation);
variableInformation.auxiliaryVariables.push_back(assertLessOrEqualKRelaxed(*solver, variableInformation, 0));
// As we are done with the setup at this point, stop the clock for the setup time.
totalSetupTime = std::chrono::high_resolution_clock::now() - setupTimeClock;
// (6) Add constraints that cut off a lot of suboptimal solutions.
STORM_LOG_DEBUG("Asserting cuts.");
assertCuts(symbolicModel, model, labelSets, psiStates, variableInformation, relevancyInformation, *solver);
stats.cutTime = assertCuts(symbolicModel, model, labelSets, psiStates, variableInformation, relevancyInformation, *solver, options.addBackwardImplicationCuts);
STORM_LOG_DEBUG("Asserted cuts.");
if (options.encodeReachability) {
assertReachabilityCuts(model, labelSets, psiStates, variableInformation, relevancyInformation, *solver);
STORM_LOG_DEBUG("Asserted reachability cuts.");
}
// As we are done with the setup at this point, stop the clock for the setup time.
totalSetupTime = std::chrono::high_resolution_clock::now() - setupTimeClock;
// (7) Find the smallest set of commands that satisfies all constraints. If the probability of
// satisfying phi until psi exceeds the given threshold, the set of labels is minimal and can be returned.
// Otherwise, the current solution has to be ruled out and the next smallest solution is retrieved from
@ -1712,11 +1744,17 @@ namespace storm {
uint_fast64_t lastSize = 0;
uint_fast64_t iterations = 0;
uint_fast64_t currentBound = 0;
uint64_t firstCounterexampleFound = 0; // The value is not queried before being set.
std::vector<double> maximalPropertyValue;
uint_fast64_t zeroProbabilityCount = 0;
uint64_t smallestCounterexampleSize = model.getNumberOfChoices(); // Definitive u
size_t smallestCounterexampleSize = model.getNumberOfChoices(); // Definitive upper bound
uint64_t progressDelay = storm::settings::getModule<storm::settings::modules::GeneralSettings>().getShowProgressDelay();
do {
++iterations;
if (result.size() > 0 && iterations > firstCounterexampleFound + options.maximumExtraIterations) {
break;
}
STORM_LOG_DEBUG("Computing minimal command set.");
solverClock = std::chrono::high_resolution_clock::now();
boost::optional<boost::container::flat_set<uint_fast64_t>> smallest = findSmallestCommandSet(*solver, variableInformation, currentBound);
@ -1781,19 +1819,21 @@ namespace storm {
}
} else {
STORM_LOG_DEBUG("Found a counterexample.");
if (result.empty()) {
// If this is the first counterexample we find, we store when we found it.
firstCounterexampleFound = iterations;
}
result.push_back(commandSet);
if (options.maximumCounterexamples > result.size()) {
STORM_LOG_DEBUG("Exclude counterexample for future.");
ruleOutBiggerSolutions(*solver, commandSet, variableInformation, relevancyInformation);
} else {
STORM_LOG_DEBUG("Stop searching for further counterexamples.");
done = true;
}
smallestCounterexampleSize = std::min(smallestCounterexampleSize, commandSet.size());
}
totalAnalysisTime += (std::chrono::high_resolution_clock::now() - analysisClock);
++iterations;
auto now = std::chrono::high_resolution_clock::now();
auto durationSinceLastMessage = std::chrono::duration_cast<std::chrono::seconds>(now - timeOfLastMessage).count();
@ -1816,6 +1856,7 @@ namespace storm {
stats.setupTime = std::chrono::duration_cast<std::chrono::milliseconds>(totalSetupTime);
stats.modelCheckingTime = std::chrono::duration_cast<std::chrono::milliseconds>(totalModelCheckingTime);
stats.solverTime = std::chrono::duration_cast<std::chrono::milliseconds>(totalSolverTime);
stats.iterations = iterations;
if (storm::settings::getModule<storm::settings::modules::CoreSettings>().isShowStatisticsSet()) {
boost::container::flat_set<uint64_t> allLabels;

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