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Implemented triangulation in a more dynamic way.

main
Tim Quatmann 6 years ago
parent
cc5faee9c0
commit
fa10087fba
3 changed files with 112 additions and 58 deletions
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  1. 1
      src/storm-pomdp/modelchecker/ApproximatePOMDPModelCheckerOptions.h
  2. 8
      src/storm-pomdp/modelchecker/ApproximatePOMDPModelchecker.cpp
  3. 161
      src/storm-pomdp/storage/BeliefManager.h

1
src/storm-pomdp/modelchecker/ApproximatePOMDPModelCheckerOptions.h
View File

@ -38,6 +38,7 @@ namespace storm {
ValueType obsThresholdIncrementFactor = storm::utility::convertNumber<ValueType>(0.1);
ValueType numericPrecision = storm::NumberTraits<ValueType>::IsExact ? storm::utility::zero<ValueType>() : storm::utility::convertNumber<ValueType>(1e-9); /// Used to decide whether two beliefs are equal
bool dynamicTriangulation = true; // Sets whether the triangulation is done in a dynamic way (yielding more precise triangulations)
};
}
}

8
src/storm-pomdp/modelchecker/ApproximatePOMDPModelchecker.cpp
View File

@ -185,7 +185,7 @@ namespace storm {
if (options.discretize) {
std::vector<uint64_t> observationResolutionVector(pomdp.getNrObservations(), options.resolutionInit);
auto manager = std::make_shared<BeliefManagerType>(pomdp, options.numericPrecision);
auto manager = std::make_shared<BeliefManagerType>(pomdp, options.numericPrecision, options.dynamicTriangulation ? BeliefManagerType::TriangulationMode::Dynamic : BeliefManagerType::TriangulationMode::Static);
if (rewardModelName) {
manager->setRewardModel(rewardModelName);
}
@ -205,7 +205,7 @@ namespace storm {
}
}
if (options.unfold) { // Underapproximation (uses a fresh Belief manager)
auto manager = std::make_shared<BeliefManagerType>(pomdp, options.numericPrecision);
auto manager = std::make_shared<BeliefManagerType>(pomdp, options.numericPrecision, options.dynamicTriangulation ? BeliefManagerType::TriangulationMode::Dynamic : BeliefManagerType::TriangulationMode::Static);
if (rewardModelName) {
manager->setRewardModel(rewardModelName);
}
@ -243,7 +243,7 @@ namespace storm {
HeuristicParameters overApproxHeuristicPar;
if (options.discretize) { // Setup and build first OverApproximation
observationResolutionVector = std::vector<uint64_t>(pomdp.getNrObservations(), options.resolutionInit);
overApproxBeliefManager = std::make_shared<BeliefManagerType>(pomdp, options.numericPrecision);
overApproxBeliefManager = std::make_shared<BeliefManagerType>(pomdp, options.numericPrecision, options.dynamicTriangulation ? BeliefManagerType::TriangulationMode::Dynamic : BeliefManagerType::TriangulationMode::Static);
if (rewardModelName) {
overApproxBeliefManager->setRewardModel(rewardModelName);
}
@ -267,7 +267,7 @@ namespace storm {
std::shared_ptr<ExplorerType> underApproximation;
HeuristicParameters underApproxHeuristicPar;
if (options.unfold) { // Setup and build first UnderApproximation
underApproxBeliefManager = std::make_shared<BeliefManagerType>(pomdp, options.numericPrecision);
underApproxBeliefManager = std::make_shared<BeliefManagerType>(pomdp, options.numericPrecision, options.dynamicTriangulation ? BeliefManagerType::TriangulationMode::Dynamic : BeliefManagerType::TriangulationMode::Static);
if (rewardModelName) {
underApproxBeliefManager->setRewardModel(rewardModelName);
}

161
src/storm-pomdp/storage/BeliefManager.h
View File

@ -20,7 +20,12 @@ namespace storm {
typedef boost::container::flat_set<StateType> BeliefSupportType;
typedef uint64_t BeliefId;
BeliefManager(PomdpType const& pomdp, BeliefValueType const& precision) : pomdp(pomdp), cc(precision, false) {
enum class TriangulationMode {
Static,
Dynamic
};
BeliefManager(PomdpType const& pomdp, BeliefValueType const& precision, TriangulationMode const& triangulationMode) : pomdp(pomdp), cc(precision, false), triangulationMode(triangulationMode) {
beliefToIdMap.resize(pomdp.getNrObservations());
initialBeliefId = computeInitialBelief();
}
@ -288,65 +293,112 @@ namespace storm {
}
};
Triangulation triangulateBelief(BeliefType belief, uint64_t resolution) {
STORM_LOG_ASSERT(assertBelief(belief), "Input belief for triangulation is not valid.");
void triangulateBeliefFreudenthal(BeliefType const& belief, uint64_t const& resolution, Triangulation& result) {
STORM_LOG_ASSERT(resolution != 0, "Invalid resolution: 0");
StateType numEntries = belief.size();
auto convResolution = storm::utility::convertNumber<BeliefValueType>(resolution);
// This is the Freudenthal Triangulation as described in Lovejoy (a whole lotta math)
// Probabilities will be triangulated to values in 0/N, 1/N, 2/N, ..., N/N
// Variable names are mostly based on the paper
// However, we speed this up a little by exploiting that belief states usually have sparse support (i.e. numEntries is much smaller than pomdp.getNumberOfStates()).
// Initialize diffs and the first row of the 'qs' matrix (aka v)
std::set<FreudenthalDiff, std::greater<FreudenthalDiff>> sorted_diffs; // d (and p?) in the paper
std::vector<BeliefValueType> qsRow; // Row of the 'qs' matrix from the paper (initially corresponds to v
qsRow.reserve(numEntries);
std::vector<StateType> toOriginalIndicesMap; // Maps 'local' indices to the original pomdp state indices
toOriginalIndicesMap.reserve(numEntries);
BeliefValueType x = convResolution;
for (auto const& entry : belief) {
qsRow.push_back(storm::utility::floor(x)); // v
sorted_diffs.emplace(toOriginalIndicesMap.size(), x - qsRow.back()); // x-v
toOriginalIndicesMap.push_back(entry.first);
x -= entry.second * convResolution;
}
// Insert a dummy 0 column in the qs matrix so the loops below are a bit simpler
qsRow.push_back(storm::utility::zero<BeliefValueType>());
result.weights.reserve(numEntries);
result.gridPoints.reserve(numEntries);
auto currentSortedDiff = sorted_diffs.begin();
auto previousSortedDiff = sorted_diffs.end();
--previousSortedDiff;
for (StateType i = 0; i < numEntries; ++i) {
// Compute the weight for the grid points
BeliefValueType weight = previousSortedDiff->diff - currentSortedDiff->diff;
if (i == 0) {
// The first weight is a bit different
weight += storm::utility::one<ValueType>();
} else {
// 'compute' the next row of the qs matrix
qsRow[previousSortedDiff->dimension] += storm::utility::one<BeliefValueType>();
}
if (!cc.isZero(weight)) {
result.weights.push_back(weight);
// Compute the grid point
BeliefType gridPoint;
for (StateType j = 0; j < numEntries; ++j) {
BeliefValueType gridPointEntry = qsRow[j] - qsRow[j + 1];
if (!cc.isZero(gridPointEntry)) {
gridPoint[toOriginalIndicesMap[j]] = gridPointEntry / convResolution;
}
}
result.gridPoints.push_back(getOrAddBeliefId(gridPoint));
}
previousSortedDiff = currentSortedDiff++;
}
}
void triangulateBeliefDynamic(BeliefType const& belief, uint64_t const& resolution, Triangulation& result) {
// Find the best resolution for this belief, i.e., N such that the largest distance between one of the belief values to a value in {i/N | 0 ≤ i ≤ N} is minimal
uint64_t finalResolution = resolution;
BeliefValueType finalResolutionDist = storm::utility::one<BeliefValueType>();
// We don't need to check resolutions that are smaller than the maximal resolution divided by 2 (as we already checked multiples of these)
for (uint64_t currResolution = resolution; currResolution > resolution / 2; --currResolution) {
BeliefValueType currResDist = storm::utility::zero<ValueType>();
BeliefValueType currResolutionConverted = storm::utility::convertNumber<BeliefValueType>(currResolution);
bool continueWithNextResolution = false;
for (auto const& belEntry : belief) {
BeliefValueType product = belEntry.second * currResolutionConverted;
BeliefValueType dist = storm::utility::abs<BeliefValueType>(product - storm::utility::round(product)) / currResolutionConverted;
if (dist > currResDist) {
if (dist > finalResolutionDist) {
// This resolution is worse than a previous resolution
continueWithNextResolution = true;
break;
}
currResDist = dist;
}
}
STORM_LOG_ASSERT(continueWithNextResolution || currResDist <= finalResolutionDist, "Distance for this resolution should not be larger than a previously checked one.");
if (!continueWithNextResolution) {
finalResolution = currResolution;
finalResolutionDist = currResDist;
}
}
STORM_LOG_TRACE("Picking resolution " << finalResolution << " for belief " << toString(belief));
// do standard freudenthal with the found resolution
triangulateBeliefFreudenthal(belief, finalResolution, result);
}
Triangulation triangulateBelief(BeliefType const& belief, uint64_t const& resolution) {
STORM_LOG_ASSERT(assertBelief(belief), "Input belief for triangulation is not valid.");
Triangulation result;
// Quickly triangulate Dirac beliefs
if (numEntries == 1u) {
if (belief.size() == 1u) {
result.weights.push_back(storm::utility::one<BeliefValueType>());
result.gridPoints.push_back(getOrAddBeliefId(belief));
} else {
auto convResolution = storm::utility::convertNumber<BeliefValueType>(resolution);
// This is the Freudenthal Triangulation as described in Lovejoy (a whole lotta math)
// Variable names are mostly based on the paper
// However, we speed this up a little by exploiting that belief states usually have sparse support (i.e. numEntries is much smaller than pomdp.getNumberOfStates()).
// Initialize diffs and the first row of the 'qs' matrix (aka v)
std::set<FreudenthalDiff, std::greater<FreudenthalDiff>> sorted_diffs; // d (and p?) in the paper
std::vector<BeliefValueType> qsRow; // Row of the 'qs' matrix from the paper (initially corresponds to v
qsRow.reserve(numEntries);
std::vector<StateType> toOriginalIndicesMap; // Maps 'local' indices to the original pomdp state indices
toOriginalIndicesMap.reserve(numEntries);
BeliefValueType x = convResolution;
for (auto const& entry : belief) {
qsRow.push_back(storm::utility::floor(x)); // v
sorted_diffs.emplace(toOriginalIndicesMap.size(), x - qsRow.back()); // x-v
toOriginalIndicesMap.push_back(entry.first);
x -= entry.second * convResolution;
}
// Insert a dummy 0 column in the qs matrix so the loops below are a bit simpler
qsRow.push_back(storm::utility::zero<BeliefValueType>());
result.weights.reserve(numEntries);
result.gridPoints.reserve(numEntries);
auto currentSortedDiff = sorted_diffs.begin();
auto previousSortedDiff = sorted_diffs.end();
--previousSortedDiff;
for (StateType i = 0; i < numEntries; ++i) {
// Compute the weight for the grid points
BeliefValueType weight = previousSortedDiff->diff - currentSortedDiff->diff;
if (i == 0) {
// The first weight is a bit different
weight += storm::utility::one<ValueType>();
} else {
// 'compute' the next row of the qs matrix
qsRow[previousSortedDiff->dimension] += storm::utility::one<BeliefValueType>();
}
if (!cc.isZero(weight)) {
result.weights.push_back(weight);
// Compute the grid point
BeliefType gridPoint;
for (StateType j = 0; j < numEntries; ++j) {
BeliefValueType gridPointEntry = qsRow[j] - qsRow[j + 1];
if (!cc.isZero(gridPointEntry)) {
gridPoint[toOriginalIndicesMap[j]] = gridPointEntry / convResolution;
}
}
result.gridPoints.push_back(getOrAddBeliefId(gridPoint));
}
previousSortedDiff = currentSortedDiff++;
switch (triangulationMode) {
case TriangulationMode::Static:
triangulateBeliefFreudenthal(belief, resolution, result);
break;
case TriangulationMode::Dynamic:
triangulateBeliefDynamic(belief, resolution, result);
break;
default:
STORM_LOG_ASSERT(false, "Invalid triangulation mode.");
}
}
STORM_LOG_ASSERT(assertTriangulation(belief, result), "Incorrect triangulation: " << toString(result));
@ -445,6 +497,7 @@ namespace storm {
storm::utility::ConstantsComparator<ValueType> cc;
TriangulationMode triangulationMode;
};
}
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