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topological linear equation solver now respects sound computations

main
TimQu 8 years ago
parent
636d2638a5
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3b7b60aa6c
2 changed files with 54 additions and 18 deletions
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  1. 67
      src/storm/solver/TopologicalLinearEquationSolver.cpp
  2. 5
      src/storm/solver/TopologicalLinearEquationSolver.h

67
src/storm/solver/TopologicalLinearEquationSolver.cpp
View File

@ -41,9 +41,14 @@ namespace storm {
}
template<typename ValueType>
storm::Environment TopologicalLinearEquationSolver<ValueType>::getEnvironmentForUnderlyingSolver(storm::Environment const& env) const {
storm::Environment TopologicalLinearEquationSolver<ValueType>::getEnvironmentForUnderlyingSolver(storm::Environment const& env, bool adaptPrecision) const {
storm::Environment subEnv(env);
subEnv.solver().setLinearEquationSolverType(env.solver().topological().getUnderlyingSolverType());
subEnv.solver().setLinearEquationSolverType(env.solver().topological().getUnderlyingSolverType(), env.solver().topological().isUnderlyingSolverTypeSetFromDefault());
if (adaptPrecision) {
STORM_LOG_ASSERT(this->longestSccChainSize, "Did not compute the longest SCC chain size although it is needed.");
auto subEnvPrec = subEnv.solver().getPrecisionOfLinearEquationSolver(subEnv.solver().getLinearEquationSolverType());
subEnv.solver().setLinearEquationSolverPrecision(static_cast<storm::RationalNumber>(subEnvPrec.first.get() / storm::utility::convertNumber<storm::RationalNumber>(this->longestSccChainSize.get())));
}
return subEnv;
}
@ -55,25 +60,32 @@ namespace storm {
//std::cout << "Initial solution vector: " << std::endl;
//std::cout << storm::utility::vector::toString(x) << std::endl;
// For sound computations we need to increase the precision in each SCC
bool needAdaptPrecision = env.solver().isForceSoundness() && env.solver().getPrecisionOfLinearEquationSolver(env.solver().topological().getUnderlyingSolverType()).first.is_initialized();
if (!this->sortedSccDecomposition) {
if (!this->sortedSccDecomposition || (needAdaptPrecision && !this->longestSccChainSize)) {
STORM_LOG_TRACE("Creating SCC decomposition.");
createSortedSccDecomposition();
createSortedSccDecomposition(needAdaptPrecision);
}
//std::cout << "Sorted SCC decomposition: " << std::endl;
for (auto const& scc : *this->sortedSccDecomposition) {
//for (auto const& scc : *this->sortedSccDecomposition) {
//std::cout << "SCC: ";
for (auto const& row : scc) {
// for (auto const& row : scc) {
//std::cout << row << " ";
}
// }
//std::cout << std::endl;
}
//}
storm::Environment sccSolverEnvironment = getEnvironmentForUnderlyingSolver(env);
// We do not need to adapt the precision if all SCCs are trivial (i.e., the system is acyclic)
needAdaptPrecision = needAdaptPrecision && (this->sortedSccDecomposition->size() != this->getMatrixRowCount());
std::cout << "Found " << this->sortedSccDecomposition->size() << "SCCs. Average size is " << static_cast<double>(x.size()) /
static_cast<double>(this->sortedSccDecomposition->size()) << "." << std::endl;
storm::Environment sccSolverEnvironment = getEnvironmentForUnderlyingSolver(env, needAdaptPrecision);
std::cout << "Found " << this->sortedSccDecomposition->size() << "SCCs. Average size is " << static_cast<double>(this->getMatrixRowCount()) / static_cast<double>(this->sortedSccDecomposition->size()) << "." << std::endl;
if (this->longestSccChainSize) {
std::cout << "Longest SCC chain size is " << this->longestSccChainSize.get() << std::endl;
}
// Handle the case where there is just one large SCC
if (this->sortedSccDecomposition->size() == 1) {
@ -102,7 +114,7 @@ namespace storm {
}
template<typename ValueType>
void TopologicalLinearEquationSolver<ValueType>::createSortedSccDecomposition() const {
void TopologicalLinearEquationSolver<ValueType>::createSortedSccDecomposition(bool needLongestChainSize) const {
// Obtain the scc decomposition
auto sccDecomposition = storm::storage::StronglyConnectedComponentDecomposition<ValueType>(*this->A);
@ -124,7 +136,11 @@ namespace storm {
// Find a topological sort via DFS.
storm::storage::BitVector unsortedSCCs(sccDecomposition.size(), true);
std::vector<uint32_t> sccStack;
std::vector<uint32_t> sccStack, chainSizes;
if (needLongestChainSize) {
chainSizes.resize(this->sortedSccDecomposition->size(), 1u);
}
uint32_t longestChainSize = 0;
uint32_t const token = std::numeric_limits<uint32_t>::max();
std::set<uint64_t> successorSCCs;
@ -132,7 +148,7 @@ namespace storm {
sccStack.push_back(firstUnsortedScc);
while (!sccStack.empty()) {
auto const& currentSccIndex = sccStack.back();
uint32_t currentSccIndex = sccStack.back();
if (currentSccIndex != token) {
// Check whether the SCC is still unprocessed
if (unsortedSCCs.get(currentSccIndex)) {
@ -157,12 +173,31 @@ namespace storm {
} else {
// all successors of the current scc have already been explored.
sccStack.pop_back(); // pop the token
sortedSCCs.push_back(std::move(sccDecomposition.getBlock(sccStack.back())));
unsortedSCCs.set(sccStack.back(), false);
currentSccIndex = sccStack.back();
storm::storage::StronglyConnectedComponent& scc = sccDecomposition.getBlock(currentSccIndex);
// Compute the longest chain size for this scc
if (needLongestChainSize) {
uint32_t& currentChainSize = chainSizes[currentSccIndex];
for (auto const& row : scc) {
for (auto const& entry : this->A->getRow(row)) {
currentChainSize = std::max(currentChainSize, chainSizes[sccIndices[entry.getColumn()]] + 1);
}
}
longestChainSize = std::max(longestChainSize, currentChainSize);
}
unsortedSCCs.set(currentSccIndex, false);
sccStack.pop_back(); // pop the current scc index
sortedSCCs.push_back(std::move(scc));
}
}
}
if (longestChainSize > 0) {
this->longestSccChainSize = longestChainSize;
}
}
template<typename ValueType>

5
src/storm/solver/TopologicalLinearEquationSolver.h
View File

@ -41,10 +41,10 @@ namespace storm {
virtual uint64_t getMatrixRowCount() const override;
virtual uint64_t getMatrixColumnCount() const override;
storm::Environment getEnvironmentForUnderlyingSolver(storm::Environment const& env) const;
storm::Environment getEnvironmentForUnderlyingSolver(storm::Environment const& env, bool adaptPrecision = false) const;
// Creates an SCC decomposition and sorts the SCCs according to a topological sort.
void createSortedSccDecomposition() const;
void createSortedSccDecomposition(bool needLongestChainSize) const;
// Solves the SCC with the given index
// ... for the case that the SCC is trivial
@ -67,6 +67,7 @@ namespace storm {
// cached auxiliary data
mutable std::unique_ptr<std::vector<storm::storage::StronglyConnectedComponent>> sortedSccDecomposition;
mutable boost::optional<uint64_t> longestSccChainSize;
mutable std::unique_ptr<storm::solver::LinearEquationSolver<ValueType>> sccSolver;
};

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