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Make dtmc model checker throw on unreachable condition when checking conditional probabilities. #946

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Make dtmc model checker throw on unreachable condition when checking conditional probabilities. #946

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e0487be
Make dtmc model checker throw on unreachable condition.
lukovdm Jul 1, 2026
5f8696b
Change exception type
lukovdm Jul 1, 2026
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1 change: 1 addition & 0 deletions resources/examples/testfiles/dtmc/test_conditional.pm
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Expand Up @@ -14,5 +14,6 @@ rewards
s=2 : 1;
endrewards

label "unreachable" = false;
label "condition" = s=2;
label "target" = s=3;
3 changes: 2 additions & 1 deletion src/storm/modelchecker/helper/conditional/ConditionalHelper.cpp
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Expand Up @@ -8,6 +8,7 @@
#include "storm/environment/modelchecker/ConditionalModelCheckerEnvironment.h"
#include "storm/environment/modelchecker/ModelCheckerEnvironment.h"
#include "storm/environment/solver/MinMaxSolverEnvironment.h"
#include "storm/exceptions/InvalidPropertyException.h"
#include "storm/exceptions/NotImplementedException.h"
#include "storm/exceptions/NotSupportedException.h"
#include "storm/modelchecker/prctl/helper/SparseMdpPrctlHelper.h"
Expand Down Expand Up @@ -1252,7 +1253,7 @@ std::optional<SolutionType> handleTrivialCases(uint64_t const initialState, Norm
if (normalForm.conditionStates.get(initialState)) {
return normalForm.getTargetValue(initialState); // The value is already known, nothing to do.
} else {
STORM_LOG_THROW(!normalForm.universalObservationFailureStates.get(initialState), storm::exceptions::NotSupportedException,
STORM_LOG_THROW(!normalForm.universalObservationFailureStates.get(initialState), storm::exceptions::InvalidPropertyException,
"Trying to compute undefined conditional probability: the condition has probability 0 under all policies.");
// The last case for a terminal initial state is that it is already target and the condition is reachable with non-zero probability.
// In this case, all schedulers induce a conditional probability of 1 (or do not reach the condition, i.e., have undefined value)
Expand Down
97 changes: 49 additions & 48 deletions src/storm/modelchecker/prctl/helper/SparseDtmcPrctlHelper.cpp
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Expand Up @@ -860,33 +860,33 @@ std::vector<SolutionType> SparseDtmcPrctlHelper<ValueType, RewardModelType, Solu
} else {
// Prepare result vector.
std::vector<ValueType> result(transitionMatrix.getRowCount(), storm::utility::infinity<ValueType>());

if (!conditionStates.empty()) {
BaierTransformedModel transformedModel =
computeBaierTransformation(env, transitionMatrix, backwardTransitions, targetStates, conditionStates, boost::none);

if (transformedModel.noTargetStates) {
storm::utility::vector::setVectorValues(result, transformedModel.beforeStates, storm::utility::zero<ValueType>());
STORM_LOG_THROW(!conditionStates.empty(), storm::exceptions::InvalidPropertyException,

@tquatmann tquatmann Jul 3, 2026

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Do we have to check that conditionStates are reachable from all relevant (i.e. initial) states?

Something like

auto const conditionGreaterZeroStates = storm::utility::graph::performProbGreater0(backwardTransitions, allStates, conditionStates);
STORM_LOG_THROW(goal.hasRelevantStates && goal.getRelevantStates().isSubsetOf(conditionGreaterZeroStates), ...);

"The condition set has probability 0, so the conditional probability is not defined.");

BaierTransformedModel transformedModel =
computeBaierTransformation(env, transitionMatrix, backwardTransitions, targetStates, conditionStates, boost::none);

if (transformedModel.noTargetStates) {
storm::utility::vector::setVectorValues(result, transformedModel.beforeStates, storm::utility::zero<ValueType>());
} else {
// At this point, we do not need to check whether there are 'before' states, since the condition
// states were non-empty so there is at least one state with a positive probability of satisfying
// the condition.

// Now compute reachability probabilities in the transformed model.
storm::storage::SparseMatrix<ValueType> const& newTransitionMatrix = transformedModel.transitionMatrix.get();
storm::storage::BitVector newRelevantValues;
if (goal.hasRelevantValues()) {
newRelevantValues = transformedModel.getNewRelevantStates(goal.relevantValues());
} else {
// At this point, we do not need to check whether there are 'before' states, since the condition
// states were non-empty so there is at least one state with a positive probability of satisfying
// the condition.

// Now compute reachability probabilities in the transformed model.
storm::storage::SparseMatrix<ValueType> const& newTransitionMatrix = transformedModel.transitionMatrix.get();
storm::storage::BitVector newRelevantValues;
if (goal.hasRelevantValues()) {
newRelevantValues = transformedModel.getNewRelevantStates(goal.relevantValues());
} else {
newRelevantValues = transformedModel.getNewRelevantStates();
}
goal.setRelevantValues(std::move(newRelevantValues));
std::vector<ValueType> conditionalProbabilities = computeUntilProbabilities(
env, std::move(goal), newTransitionMatrix, newTransitionMatrix.transpose(),
storm::storage::BitVector(newTransitionMatrix.getRowCount(), true), transformedModel.targetStates.get(), qualitative);

storm::utility::vector::setVectorValues(result, transformedModel.beforeStates, conditionalProbabilities);
newRelevantValues = transformedModel.getNewRelevantStates();
}
goal.setRelevantValues(std::move(newRelevantValues));
std::vector<ValueType> conditionalProbabilities =
computeUntilProbabilities(env, std::move(goal), newTransitionMatrix, newTransitionMatrix.transpose(),
storm::storage::BitVector(newTransitionMatrix.getRowCount(), true), transformedModel.targetStates.get(), qualitative);

storm::utility::vector::setVectorValues(result, transformedModel.beforeStates, conditionalProbabilities);
}

return result;
Expand All @@ -901,34 +901,35 @@ std::vector<SolutionType> SparseDtmcPrctlHelper<ValueType, RewardModelType, Solu
if constexpr (storm::IsIntervalType<ValueType>) {
STORM_LOG_THROW(false, storm::exceptions::NotImplementedException, "We do not support computing conditional rewards with interval models.");
} else {
STORM_LOG_THROW(!conditionStates.empty(), storm::exceptions::InvalidPropertyException,
"The condition set has probability 0, so the conditional probability is not defined.");

// Prepare result vector.
std::vector<ValueType> result(transitionMatrix.getRowCount(), storm::utility::infinity<ValueType>());

if (!conditionStates.empty()) {
BaierTransformedModel transformedModel = computeBaierTransformation(env, transitionMatrix, backwardTransitions, targetStates, conditionStates,
rewardModel.getTotalRewardVector(transitionMatrix));

if (transformedModel.noTargetStates) {
storm::utility::vector::setVectorValues(result, transformedModel.beforeStates, storm::utility::zero<ValueType>());
BaierTransformedModel transformedModel = computeBaierTransformation(env, transitionMatrix, backwardTransitions, targetStates, conditionStates,
rewardModel.getTotalRewardVector(transitionMatrix));

if (transformedModel.noTargetStates) {
storm::utility::vector::setVectorValues(result, transformedModel.beforeStates, storm::utility::zero<ValueType>());
} else {
// At this point, we do not need to check whether there are 'before' states, since the condition
// states were non-empty so there is at least one state with a positive probability of satisfying
// the condition.

// Now compute reachability probabilities in the transformed model.
storm::storage::SparseMatrix<ValueType> const& newTransitionMatrix = transformedModel.transitionMatrix.get();
storm::storage::BitVector newRelevantValues;
if (goal.hasRelevantValues()) {
newRelevantValues = transformedModel.getNewRelevantStates(goal.relevantValues());
} else {
// At this point, we do not need to check whether there are 'before' states, since the condition
// states were non-empty so there is at least one state with a positive probability of satisfying
// the condition.

// Now compute reachability probabilities in the transformed model.
storm::storage::SparseMatrix<ValueType> const& newTransitionMatrix = transformedModel.transitionMatrix.get();
storm::storage::BitVector newRelevantValues;
if (goal.hasRelevantValues()) {
newRelevantValues = transformedModel.getNewRelevantStates(goal.relevantValues());
} else {
newRelevantValues = transformedModel.getNewRelevantStates();
}
goal.setRelevantValues(std::move(newRelevantValues));
std::vector<ValueType> conditionalRewards =
computeReachabilityRewards(env, std::move(goal), newTransitionMatrix, newTransitionMatrix.transpose(), transformedModel.stateRewards.get(),
transformedModel.targetStates.get(), qualitative);
storm::utility::vector::setVectorValues(result, transformedModel.beforeStates, conditionalRewards);
newRelevantValues = transformedModel.getNewRelevantStates();
}
goal.setRelevantValues(std::move(newRelevantValues));
std::vector<ValueType> conditionalRewards =
computeReachabilityRewards(env, std::move(goal), newTransitionMatrix, newTransitionMatrix.transpose(), transformedModel.stateRewards.get(),
transformedModel.targetStates.get(), qualitative);
storm::utility::vector::setVectorValues(result, transformedModel.beforeStates, conditionalRewards);
}

return result;
Expand Down
9 changes: 9 additions & 0 deletions src/test/storm/modelchecker/prctl/dtmc/ConditionalDtmcPrctlModelCheckerTest.cpp
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Expand Up @@ -7,6 +7,7 @@
#include "storm/environment/solver/EigenSolverEnvironment.h"
#include "storm/environment/solver/GmmxxSolverEnvironment.h"
#include "storm/environment/solver/NativeSolverEnvironment.h"
#include "storm/exceptions/InvalidPropertyException.h"
#include "storm/logic/Formulas.h"
#include "storm/modelchecker/prctl/SparseDtmcPrctlModelChecker.h"
#include "storm/modelchecker/results/ExplicitQuantitativeCheckResult.h"
Expand Down Expand Up @@ -165,6 +166,10 @@ TYPED_TEST(ConditionalDtmcPrctlModelCheckerTest, Conditional) {
storm::modelchecker::ExplicitQuantitativeCheckResult<ValueType>& quantitativeResult2 = result->asExplicitQuantitativeCheckResult<ValueType>();
EXPECT_NEAR(storm::utility::one<ValueType>(), quantitativeResult2[0], this->precision());

formula = formulaParser.parseSingleFormulaFromString("P=? [F \"target\" || F \"unreachable\"]");

STORM_SILENT_EXPECT_THROW(checker.check(this->env(), *formula), storm::exceptions::InvalidPropertyException);

formula = formulaParser.parseSingleFormulaFromString("R=? [F \"target\"]");

result = checker.check(this->env(), *formula);
Expand All @@ -176,5 +181,9 @@ TYPED_TEST(ConditionalDtmcPrctlModelCheckerTest, Conditional) {
result = checker.check(this->env(), *formula);
storm::modelchecker::ExplicitQuantitativeCheckResult<ValueType>& quantitativeResult4 = result->asExplicitQuantitativeCheckResult<ValueType>();
EXPECT_NEAR(storm::utility::one<ValueType>(), quantitativeResult4[0], this->precision());

formula = formulaParser.parseSingleFormulaFromString("R=? [F \"target\" || F \"unreachable\"]");

STORM_SILENT_EXPECT_THROW(checker.check(this->env(), *formula), storm::exceptions::InvalidPropertyException);
}
} // namespace
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