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LpChecker: Added a redundant constraint, improved stability.

tempestpy_adaptions
Tim Quatmann 5 years ago
parent
63fe1c01d1
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622926d9c1
1 changed files with 24 additions and 21 deletions
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  1. 33
      src/storm/modelchecker/multiobjective/deterministicScheds/DeterministicSchedsLpChecker.cpp

33
src/storm/modelchecker/multiobjective/deterministicScheds/DeterministicSchedsLpChecker.cpp
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@ -177,26 +177,22 @@ namespace storm {
template <typename ValueType>
std::map<uint64_t, storm::expressions::Expression> processEc(storm::storage::MaximalEndComponent const& ec, storm::storage::SparseMatrix<ValueType> const& transitions, std::string const& varNameSuffix, std::vector<storm::expressions::Expression> const& choiceVars, storm::solver::LpSolver<ValueType>& lpModel) {
std::map<uint64_t, storm::expressions::Expression> ecStateVars, ecChoiceVars, ecFlowChoiceVars;
// Compute an upper bound on the expected number of visits of the states in this ec.
// First get a lower bound l on the probability of a path that leaves this MEC. 1-l is an upper bound on Pr_s(X F s).
// The desired upper bound is thus 1/(1-(1-l)) = 1/l. See Baier et al., CAV'17
// To compute l, we multiply the smallest transition probabilities occurring at each state and MEC-Choice
// as well as the smallest 'exit' probability
// Observe that the actual transition probabilities do not matter for this encoding.
// Hence, we assume that all distributions are uniform to achieve a better (numerically more stable) bound
ValueType lpath = storm::utility::one<ValueType>();
for (auto const& stateChoices : ec) {
ValueType minProb = storm::utility::one<ValueType>();
uint64_t maxEntryCount = transitions.getColumnCount();
// Choices that leave the EC are not considered in the in[s] below. Hence, also do not need to consider them here.
for (auto const& choice : stateChoices.second) {
// Get the minimum over all transition probabilities
for (auto const& transition : transitions.getRow(choice)) {
if (!storm::utility::isZero(transition.getValue())) {
minProb = std::min(minProb, transition.getValue());
}
}
maxEntryCount = std::max(maxEntryCount, transitions.getRow(choice).getNumberOfEntries());
}
lpath *= minProb;
lpath *= storm::utility::one<ValueType>() / storm::utility::convertNumber<ValueType>(maxEntryCount);
}
ValueType expVisitsUpperBound = storm::utility::one<ValueType>() / lpath;
STORM_LOG_WARN_COND(expVisitsUpperBound <= storm::utility::convertNumber<ValueType>(1000.0), "Large upper bound for expected visiting times: " << expVisitsUpperBound);
@ -210,7 +206,7 @@ namespace storm {
}
// create constraints
std::map<uint64_t, std::vector<storm::expressions::Expression>> ins, outs;
std::map<uint64_t, std::vector<storm::expressions::Expression>> ins, outs, ecIns;
for (auto const& stateChoices : ec) {
std::vector<storm::expressions::Expression> ecChoiceVarsAtState;
std::vector<storm::expressions::Expression> out;
@ -221,11 +217,11 @@ namespace storm {
}
ecChoiceVarsAtState.push_back(ecChoiceVars[choice]);
out.push_back(ecFlowChoiceVars[choice]);
ValueType fakeProbability = storm::utility::one<ValueType>() / storm::utility::convertNumber<ValueType, uint64_t>(transitions.getRow(choice).getNumberOfEntries());
for (auto const& transition : transitions.getRow(choice)) {
if (!storm::utility::isZero(transition.getValue())) {
lpModel.addConstraint("", ecChoiceVars[choice] <= ecStateVars[transition.getColumn()]);
ins[transition.getColumn()].push_back(lpModel.getConstant(transition.getValue()) * ecFlowChoiceVars[choice]);
}
ins[transition.getColumn()].push_back(lpModel.getConstant(fakeProbability) * ecFlowChoiceVars[choice]);
ecIns[transition.getColumn()].push_back(ecChoiceVars[choice]);
}
}
lpModel.addConstraint("", ecStateVars[stateChoices.first] == storm::expressions::sum(ecChoiceVarsAtState));
@ -247,7 +243,10 @@ namespace storm {
in->second.push_back(lpModel.getConstant(storm::utility::one<ValueType>() / storm::utility::convertNumber<ValueType>(numStates)));
auto out = outs.find(stateChoices.first);
STORM_LOG_ASSERT(out != outs.end(), "out flow of ec state was not set.");
lpModel.addConstraint("", storm::expressions::sum(in->second)<= storm::expressions::sum(out->second));
lpModel.addConstraint("", storm::expressions::sum(in->second) <= storm::expressions::sum(out->second));
auto ecIn = ecIns.find(stateChoices.first);
STORM_LOG_ASSERT(ecIn != ecIns.end(), "ec state does not seem to have an incoming transition.");
lpModel.addConstraint("", storm::expressions::sum(ecIn->second) >= ecStateVars[stateChoices.first]);
}
return ecStateVars;
@ -270,6 +269,7 @@ namespace storm {
storm::storage::MaximalEndComponentDecomposition<ValueType> mecs(model.getTransitionMatrix(), backwardTransitions, storm::storage::BitVector(model.getNumberOfStates(), true), choicesWithValueZero);
for (auto const& mec : mecs) {
// For each objective we might need to split this mec into several subECs, if the objective yields a non-zero scheduler-independent state value for some states of this ec.
// However, note that this split happens objective-wise which is why we can not consider a subsystem in the mec-decomposition above
std::map<std::set<uint64_t>, std::vector<uint64_t>> excludedStatesToObjIndex;
bool mecContainsSchedulerDependentValue = false;
for (uint64_t objIndex = 0; objIndex < objectiveHelper.size(); ++objIndex) {
@ -339,7 +339,7 @@ namespace storm {
} else {
flowEncoding = env.modelchecker().multi().getEncodingType() == storm::MultiObjectiveModelCheckerEnvironment::EncodingType::Flow;
}
STORM_PRINT_AND_LOG("Using " << (flowEncoding ? "flow" : "classical") << " encoding." << std::endl);
STORM_LOG_INFO("Using " << (flowEncoding ? "flow" : "classical") << " encoding." << std::endl);
uint64_t numStates = model.getNumberOfStates();
uint64_t initialState = *model.getInitialStates().begin();
@ -521,6 +521,7 @@ namespace storm {
}
}
for (auto const& transition : model.getTransitionMatrix().getRow(state, choice)) {
if (!storm::utility::isZero(transition.getValue())) {
storm::expressions::Expression transitionValue = lpModel->getConstant(transition.getValue()) * stateVars[transition.getColumn()];
if (choiceValue.isInitialized()) {
choiceValue = choiceValue + transitionValue;
@ -528,6 +529,7 @@ namespace storm {
choiceValue = transitionValue;
}
}
}
choiceValue = choiceValue.simplify().reduceNesting();
if (numChoices == 1) {
stateValue = choiceValue;
@ -563,6 +565,7 @@ namespace storm {
if (ecVar.isInitialized()) {
// if this state is part of an ec, make sure to assign a value of zero.
if (objectiveHelper[objIndex].minimizing()) {
// This part is optional
lpModel->addConstraint("", stateVars[state] >= (ecVar - one) * lpModel->getConstant(objectiveHelper[objIndex].getUpperValueBoundAtState(env, state)));
} else {
lpModel->addConstraint("", stateVars[state] <= (one - ecVar) * lpModel->getConstant(objectiveHelper[objIndex].getUpperValueBoundAtState(env, state)));

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