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First improvement step for Freudenthal triangulation

tempestpy_adaptions
Tim Quatmann 5 years ago
parent
eca4dab6c0
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937659f356
1 changed files with 73 additions and 57 deletions
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  1. 118
      src/storm-pomdp/storage/BeliefManager.h

118
src/storm-pomdp/storage/BeliefManager.h
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@ -263,78 +263,94 @@ namespace storm {
return pomdp.getObservation(belief.begin()->first);
}
struct FreudenthalData {
FreudenthalData(StateType const& pomdpState, StateType const& dimension, BeliefValueType const& x) : pomdpState(pomdpState), dimension(dimension), value(storm::utility::floor(x)), diff(x-value) { };
StateType pomdpState;
StateType dimension; // i
BeliefValueType value; // v[i] in the Lovejoy paper
BeliefValueType diff; // d[i] in the Lovejoy paper
};
struct FreudenthalDataComparator {
bool operator()(FreudenthalData const& first, FreudenthalData const& second) const {
if (first.diff != second.diff) {
return first.diff > second.diff;
} else {
return first.dimension < second.dimension;
}
}
};
Triangulation triangulateBelief(BeliefType belief, uint64_t resolution) {
//TODO this can also be simplified using the sparse vector interpretation
//TODO Enable chaching for this method?
STORM_LOG_ASSERT(assertBelief(belief), "Input belief for triangulation is not valid.");
auto nrStates = pomdp.getNumberOfStates();
auto convResolution = storm::utility::convertNumber<BeliefValueType>(resolution);
// This is the Freudenthal Triangulation as described in Lovejoy (a whole lotta math)
// Variable names are based on the paper
// TODO avoid reallocations for these vectors
std::vector<BeliefValueType> x(nrStates);
std::vector<BeliefValueType> v(nrStates);
std::vector<BeliefValueType> d(nrStates);
auto convResolution = storm::utility::convertNumber<BeliefValueType>(resolution);
for (size_t i = 0; i < nrStates; ++i) {
for (auto const &probEntry : belief) {
if (probEntry.first >= i) {
x[i] += convResolution * probEntry.second;
}
}
v[i] = storm::utility::floor(x[i]);
d[i] = x[i] - v[i];
// However, we speed this up a little by exploiting that belief states usually have sparse support.
// TODO: for the sorting, it probably suffices to have a map from diffs to dimensions. The other Freudenthaldata could then also be stored in vectors, which would be a bit more like the original algorithm
// Initialize some data
std::vector<typename std::set<FreudenthalData, FreudenthalDataComparator>::iterator> dataIterators;
dataIterators.reserve(belief.size());
// Initialize first row of 'qs' matrix
std::vector<BeliefValueType> qsRow;
qsRow.reserve(dataIterators.size());
std::set<FreudenthalData, FreudenthalDataComparator> freudenthalData;
BeliefValueType x = convResolution;
for (auto const& entry : belief) {
auto insertionIt = freudenthalData.emplace(entry.first, dataIterators.size(), x).first;
dataIterators.push_back(insertionIt);
qsRow.push_back(dataIterators.back()->value);
x -= entry.second * convResolution;
}
qsRow.push_back(storm::utility::zero<BeliefValueType>());
assert(!freudenthalData.empty());
auto p = storm::utility::vector::getSortedIndices(d);
std::vector<std::vector<BeliefValueType>> qs(nrStates, std::vector<BeliefValueType>(nrStates));
for (size_t i = 0; i < nrStates; ++i) {
if (i == 0) {
for (size_t j = 0; j < nrStates; ++j) {
qs[i][j] = v[j];
}
} else {
for (size_t j = 0; j < nrStates; ++j) {
if (j == p[i - 1]) {
qs[i][j] = qs[i - 1][j] + storm::utility::one<BeliefValueType>();
} else {
qs[i][j] = qs[i - 1][j];
}
Triangulation result;
result.weights.reserve(freudenthalData.size());
result.gridPoints.reserve(freudenthalData.size());
// Insert first grid point
// TODO: this special treatment is actually not necessary.
BeliefValueType firstWeight = storm::utility::one<ValueType>() - freudenthalData.begin()->diff + freudenthalData.rbegin()->diff;
if (!cc.isZero(firstWeight)) {
result.weights.push_back(firstWeight);
BeliefType gridPoint;
for (StateType j = 0; j < dataIterators.size(); ++j) {
BeliefValueType gridPointEntry = qsRow[j] - qsRow[j + 1];
if (!cc.isZero(gridPointEntry)) {
gridPoint[dataIterators[j]->pomdpState] = gridPointEntry / convResolution;
}
}
result.gridPoints.push_back(getOrAddBeliefId(gridPoint));
}
Triangulation result;
// The first weight is 1-sum(other weights). We therefore process the js in reverse order
BeliefValueType firstWeight = storm::utility::one<BeliefValueType>();
for (size_t j = nrStates; j > 0;) {
--j;
// First create the weights. The weights vector will be reversed at the end.
ValueType weight;
if (j == 0) {
weight = firstWeight;
} else {
weight = d[p[j - 1]] - d[p[j]];
firstWeight -= weight;
}
if (freudenthalData.size() > 1) {
// Insert remaining grid points
auto currentSortedEntry = freudenthalData.begin();
auto previousSortedEntry = currentSortedEntry++;
for (StateType i = 1; i < dataIterators.size(); ++i) {
// 'compute' the next row of the qs matrix
qsRow[previousSortedEntry->dimension] += storm::utility::one<BeliefValueType>();
BeliefValueType weight = previousSortedEntry->diff - currentSortedEntry->diff;
if (!cc.isZero(weight)) {
result.weights.push_back(weight);
BeliefType gridPoint;
auto const& qsj = qs[j];
for (size_t i = 0; i < nrStates - 1; ++i) {
BeliefValueType gridPointEntry = qsj[i] - qsj[i + 1];
for (StateType j = 0; j < dataIterators.size(); ++j) {
BeliefValueType gridPointEntry = qsRow[j] - qsRow[j + 1];
if (!cc.isZero(gridPointEntry)) {
gridPoint[i] = gridPointEntry / convResolution;
}
gridPoint[dataIterators[j]->pomdpState] = gridPointEntry / convResolution;
}
if (!cc.isZero(qsj[nrStates - 1])) {
gridPoint[nrStates - 1] = qsj[nrStates - 1] / convResolution;
}
result.gridPoints.push_back(getOrAddBeliefId(gridPoint));
}
++previousSortedEntry;
++currentSortedEntry;
}
}
STORM_LOG_ASSERT(assertTriangulation(belief, result), "Incorrect triangulation: " << toString(result));

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