Alexander Bork
6 years ago
7 changed files with 340 additions and 237 deletions
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13src/storm-dft/api/storm-dft.cpp
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4src/storm-dft/api/storm-dft.h
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185src/storm-dft/modelchecker/dft/DFTASFChecker.cpp
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50src/storm-dft/modelchecker/dft/DFTASFChecker.h
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241src/storm-dft/utility/FailureBoundFinder.cpp
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73src/storm-dft/utility/FailureBoundFinder.h
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11src/test/storm-dft/api/DftSmtTest.cpp
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#include "FailureBoundFinder.h"
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namespace storm { |
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namespace dft { |
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namespace utility { |
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uint64_t |
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FailureBoundFinder::correctLowerBound(std::shared_ptr<storm::modelchecker::DFTASFChecker> smtchecker, |
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uint64_t bound, uint_fast64_t timeout) { |
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STORM_LOG_DEBUG("Lower bound correction - try to correct bound " << std::to_string(bound)); |
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uint64_t boundCandidate = bound; |
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uint64_t nrDepEvents = 0; |
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uint64_t nrNonMarkovian = 0; |
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auto dft = smtchecker->getDFT(); |
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// Count dependent events
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for (size_t i = 0; i < dft.nrElements(); ++i) { |
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std::shared_ptr<storm::storage::DFTElement<double> const> element = dft.getElement(i); |
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if (element->type() == storm::storage::DFTElementType::BE_EXP || |
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element->type() == storm::storage::DFTElementType::BE_CONST) { |
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auto be = std::static_pointer_cast<storm::storage::DFTBE<double> const>(element); |
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if (be->hasIngoingDependencies()) { |
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++nrDepEvents; |
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} |
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} |
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} |
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// Only need to check as long as bound candidate + nr of non-Markovians to check is smaller than number of dependent events
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while (nrNonMarkovian <= nrDepEvents && boundCandidate >= 0) { |
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if (nrNonMarkovian == 0 and boundCandidate == 0) { |
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nrNonMarkovian = 1; |
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} |
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STORM_LOG_TRACE( |
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"Lower bound correction - check possible bound " << std::to_string(boundCandidate) |
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<< " with " |
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<< std::to_string(nrNonMarkovian) |
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<< " non-Markovian states"); |
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// The uniqueness transformation for constantly failed BEs guarantees that a DFT never fails
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// in step 0 without intermediate non-Markovians, thus forcibly set nrNonMarkovian
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smtchecker->setSolverTimeout(timeout * 1000); |
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storm::solver::SmtSolver::CheckResult tmp_res = |
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smtchecker->checkFailsLeqWithEqNonMarkovianState(boundCandidate + nrNonMarkovian, |
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nrNonMarkovian); |
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smtchecker->unsetSolverTimeout(); |
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switch (tmp_res) { |
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case storm::solver::SmtSolver::CheckResult::Sat: |
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/* If SAT, there is a sequence where only boundCandidate-many BEs fail directly and rest is nonMarkovian.
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* Bound candidate is vaild, therefore check the next one */ |
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STORM_LOG_TRACE("Lower bound correction - SAT"); |
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// Prevent integer underflow
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if (boundCandidate == 0) { |
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STORM_LOG_DEBUG("Lower bound correction - corrected bound to 0"); |
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return 0; |
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} |
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--boundCandidate; |
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break; |
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case storm::solver::SmtSolver::CheckResult::Unknown: |
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// If any query returns unknown, we cannot be sure about the bound and fall back to the naive one
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STORM_LOG_DEBUG("Lower bound correction - Solver returned 'Unknown', corrected to 1"); |
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return 1; |
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default: |
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// if query is UNSAT, increase number of non-Markovian states and try again
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STORM_LOG_TRACE("Lower bound correction - UNSAT"); |
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++nrNonMarkovian; |
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break; |
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} |
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} |
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// if for one candidate all queries are UNSAT, it is not valid. Return last valid candidate
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STORM_LOG_DEBUG("Lower bound correction - corrected bound to " << std::to_string(boundCandidate + 1)); |
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return boundCandidate + 1; |
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} |
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uint64_t |
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FailureBoundFinder::correctUpperBound(std::shared_ptr<storm::modelchecker::DFTASFChecker> smtchecker, |
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uint64_t bound, uint_fast64_t timeout) { |
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STORM_LOG_DEBUG("Upper bound correction - try to correct bound " << std::to_string(bound)); |
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uint64_t boundCandidate = bound; |
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uint64_t nrDepEvents = 0; |
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uint64_t nrNonMarkovian = 0; |
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uint64_t currentTimepoint = 0; |
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auto dft = smtchecker->getDFT(); |
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// Count dependent events
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for (size_t i = 0; i < dft.nrElements(); ++i) { |
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std::shared_ptr<storm::storage::DFTElement<double> const> element = dft.getElement(i); |
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if (element->type() == storm::storage::DFTElementType::BE_EXP || |
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element->type() == storm::storage::DFTElementType::BE_CONST) { |
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auto be = std::static_pointer_cast<storm::storage::DFTBE<double> const>(element); |
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if (be->hasIngoingDependencies()) { |
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++nrDepEvents; |
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} |
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} |
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} |
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while (boundCandidate >= 0) { |
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currentTimepoint = bound + 1; |
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while (currentTimepoint - boundCandidate > 0) { |
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--currentTimepoint; |
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nrNonMarkovian = currentTimepoint - boundCandidate; |
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STORM_LOG_TRACE( |
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"Upper bound correction - candidate " << std::to_string(boundCandidate) |
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<< " check split " |
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<< |
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std::to_string(currentTimepoint) << "|" |
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<< std::to_string(nrNonMarkovian)); |
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smtchecker->setSolverTimeout(timeout * 1000); |
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storm::solver::SmtSolver::CheckResult tmp_res = |
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smtchecker->checkFailsAtTimepointWithEqNonMarkovianState(currentTimepoint, |
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nrNonMarkovian); |
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smtchecker->unsetSolverTimeout(); |
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switch (tmp_res) { |
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case storm::solver::SmtSolver::CheckResult::Sat: |
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STORM_LOG_TRACE("Upper bound correction - SAT"); |
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STORM_LOG_DEBUG("Upper bound correction - corrected to bound " << boundCandidate << |
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" (TLE can fail at sequence point " |
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<< std::to_string( |
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currentTimepoint) |
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<< " with " |
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<< std::to_string( |
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nrNonMarkovian) |
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<< " non-Markovian states)"); |
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return boundCandidate; |
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case storm::solver::SmtSolver::CheckResult::Unknown: |
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// If any query returns unknown, we cannot be sure about the bound and fall back to the naive one
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STORM_LOG_DEBUG( |
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"Upper bound correction - Solver returned 'Unknown', corrected to bound " |
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<< bound); |
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return bound; |
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default: |
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// if query is UNSAT, increase number of non-Markovian states and try again
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STORM_LOG_TRACE("Lower bound correction - UNSAT"); |
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break; |
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} |
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} |
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--boundCandidate; |
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} |
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// if for one candidate all queries are UNSAT, it is not valid. Return last valid candidate
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STORM_LOG_DEBUG("Upper bound correction - corrected bound to " << std::to_string(boundCandidate)); |
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return boundCandidate; |
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} |
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uint64_t FailureBoundFinder::getLeastFailureBound(storm::storage::DFT<double> const &dft, |
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bool useSMT, uint_fast64_t timeout) { |
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if (useSMT) { |
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STORM_LOG_TRACE("Compute lower bound for number of BE failures necessary for the DFT to fail"); |
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storm::modelchecker::DFTASFChecker smtchecker(dft); |
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smtchecker.activateExperimentalMode(); |
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smtchecker.toSolver(); |
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uint64_t bound = 0; |
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while (bound < dft.nrBasicElements() + 1) { |
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smtchecker.setSolverTimeout(timeout * 1000); |
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storm::solver::SmtSolver::CheckResult tmp_res = smtchecker.checkTleFailsWithLeq(bound); |
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smtchecker.unsetSolverTimeout(); |
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switch (tmp_res) { |
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case storm::solver::SmtSolver::CheckResult::Sat: |
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if (!dft.getDependencies().empty()) { |
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return correctLowerBound( |
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std::make_shared<storm::modelchecker::DFTASFChecker>(smtchecker), bound, |
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timeout); |
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} else { |
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return bound; |
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} |
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case storm::solver::SmtSolver::CheckResult::Unknown: |
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STORM_LOG_DEBUG("Lower bound: Solver returned 'Unknown'"); |
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return bound; |
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default: |
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++bound; |
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break; |
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} |
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} |
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return bound; |
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} else { |
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// naive bound
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return 1; |
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} |
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} |
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uint64_t FailureBoundFinder::getLeastFailureBound(storm::storage::DFT<RationalFunction> const &dft, |
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bool useSMT, uint_fast64_t timeout) { |
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if (useSMT) { |
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STORM_LOG_WARN("SMT encoding does not support rational functions"); |
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} |
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return 1; |
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} |
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uint64_t FailureBoundFinder::getAlwaysFailedBound(storm::storage::DFT<double> const &dft, bool useSMT, |
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uint_fast64_t timeout) { |
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STORM_LOG_TRACE("Compute bound for number of BE failures such that the DFT always fails"); |
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if (useSMT) { |
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storm::modelchecker::DFTASFChecker smtchecker(dft); |
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smtchecker.activateExperimentalMode(); |
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smtchecker.toSolver(); |
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if (smtchecker.checkTleNeverFailed() == storm::solver::SmtSolver::CheckResult::Sat) { |
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return dft.nrBasicElements() + 1; |
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} |
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uint64_t bound = dft.nrBasicElements(); |
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while (bound >= 0) { |
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smtchecker.setSolverTimeout(timeout * 1000); |
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storm::solver::SmtSolver::CheckResult tmp_res = smtchecker.checkTleFailsWithEq(bound); |
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smtchecker.unsetSolverTimeout(); |
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switch (tmp_res) { |
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case storm::solver::SmtSolver::CheckResult::Sat: |
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if (!dft.getDependencies().empty()) { |
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return correctUpperBound( |
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std::make_shared<storm::modelchecker::DFTASFChecker>(smtchecker), bound, |
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timeout); |
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} else { |
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return bound; |
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} |
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case storm::solver::SmtSolver::CheckResult::Unknown: |
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STORM_LOG_DEBUG("Upper bound: Solver returned 'Unknown'"); |
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return bound; |
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default: |
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--bound; |
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break; |
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} |
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} |
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return bound; |
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} else { |
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// naive bound
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return dft.nrBasicElements() + 1; |
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} |
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} |
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uint64_t |
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FailureBoundFinder::getAlwaysFailedBound(storm::storage::DFT<RationalFunction> const &dft, bool useSMT, |
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uint_fast64_t timeout) { |
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if (useSMT) { |
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STORM_LOG_WARN("SMT encoding does not support rational functions"); |
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} |
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return dft.nrBasicElements() + 1; |
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} |
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class FailureBoundFinder; |
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} |
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} |
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} |
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@ -0,0 +1,73 @@ |
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#include <vector> |
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#include "storm-dft/storage/dft/DFT.h" |
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#include "storm-dft/modelchecker/dft/DFTASFChecker.h" |
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namespace storm { |
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namespace dft { |
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namespace utility { |
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class FailureBoundFinder { |
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public: |
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/** |
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* Get the minimal number of BEs necessary for the TLE to fail (lower bound for number of failures to check) |
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* |
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* @param dft the DFT to check |
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* @param useSMT if set, an SMT solver is used to improve the bounds |
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* @param timeout timeout for each query in seconds, defaults to 10 seconds |
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* @return the minimal number |
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*/ |
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static uint64_t getLeastFailureBound(storm::storage::DFT<double> const &dft, |
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bool useSMT = false, |
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uint_fast64_t timeout = 10); |
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static uint64_t getLeastFailureBound(storm::storage::DFT<storm::RationalFunction> const &dft, |
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bool useSMT = false, |
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uint_fast64_t timeout = 10); |
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/** |
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* Get the number of BE failures for which the TLE always fails (upper bound for number of failures to check). |
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* |
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* @param dft the DFT to check |
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* @param useSMT if set, an SMT solver is used to improve the bounds |
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* @param timeout timeout for each query in seconds, defaults to 10 seconds |
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* @return the number |
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*/ |
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static uint64_t getAlwaysFailedBound(storm::storage::DFT<double> const &dft, |
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bool useSMT = false, |
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uint_fast64_t timeout = 10); |
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static uint64_t getAlwaysFailedBound(storm::storage::DFT<storm::RationalFunction> const &dft, |
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bool useSMT = false, |
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uint_fast64_t timeout = 10); |
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private: |
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/** |
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* Helper function for correction of least failure bound when dependencies are present. |
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* The main idea is to check if a later point of failure for the TLE than the pre-computed bound exists, but |
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* up until that point the number of non-Markovian states visited is so large, that less than the pre-computed bound BEs fail by themselves. |
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* The corrected bound is then (newTLEFailureTimepoint)-(nrNonMarkovianStatesVisited). This term is minimized. |
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* |
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* @param smtchecker the SMT checker to use |
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* @param bound known lower bound to be corrected |
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* @param timeout timeout timeout for each query in seconds |
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* @return the corrected bound |
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*/ |
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static uint64_t |
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correctLowerBound(std::shared_ptr<storm::modelchecker::DFTASFChecker> smtchecker, uint64_t bound, |
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uint_fast64_t timeout); |
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/** |
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* Helper function for correction of bound for number of BEs such that the DFT always fails when dependencies are present |
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* |
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* @param smtchecker the SMT checker to use |
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* @param bound known bound to be corrected |
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* @param timeout timeout timeout for each query in seconds |
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* @return the corrected bound |
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*/ |
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static uint64_t |
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correctUpperBound(std::shared_ptr<storm::modelchecker::DFTASFChecker> smtchecker, uint64_t bound, |
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uint_fast64_t timeout); |
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}; |
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} |
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} |
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} |
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