@ -265,8 +265,8 @@ namespace storm {
// Determine the set of initial states of the sub-DTMC.
storm : : storage : : BitVector newInitialStates = dtmc . getInitialStates ( ) % maybeStates ;
// Create a vector for the probabilities to go to a state with probability 1 in one step .
std : : vector < ValueType > oneStepProbabilities = dtmc . getTransitionMatrix ( ) . getConstrainedRowSumVector ( maybeStates , statesWithProbability1 ) ;
// Create a dummy vector for the one-step probabilities .
std : : vector < ValueType > oneStepProbabilities ( maybeStates . getNumberOfSetBits ( ) , storm : : utility : : zero < ValueType > ( ) ) ;
// We then build the submatrix that only has the transitions of the maybe states.
storm : : storage : : SparseMatrix < ValueType > submatrix = dtmc . getTransitionMatrix ( ) . getSubmatrix ( false , maybeStates , maybeStates ) ;
@ -303,70 +303,59 @@ namespace storm {
}
STORM_PRINT_AND_LOG ( " Eliminated " < < states . size ( ) < < " states. " < < std : : endl ) ;
flexibleMatrix . print ( ) ;
// FIXME: Eliminate backward transitions to initial state.
// At this point, the initial state has one of the following three scenarios:
// (a) only phi successors
// (b) only psi successors
// (c) phi and psi successors
//
// Case (a): ???
// Case (b): then we can add the probability of all transitions emanating from the initial state (=: p)
// and then use the regular scheme to compute the probability to reach a phi state (=: q) and then
// compute the result to be q/p.
// Case (c):
// Find first occurring representatives.
bool foundPhiRepresentative = false ;
storm : : storage : : sparse : : state_type phiRepresentative ;
bool foundPsiRepresentative = false ;
storm : : storage : : sparse : : state_type psiRepresentative ;
for ( auto initialState : newInitialStates ) {
for ( auto const & trans : flexibleMatrix . getRow ( initialState ) ) {
if ( ! foundPhiRepresentative & & phiStates . get ( trans . getColumn ( ) ) ) {
foundPhiRepresentative = true ;
phiRepresentative = trans . getColumn ( ) ;
STORM_LOG_DEBUG ( " Found phi representative " < < phiRepresentative ) ;
} else if ( ! foundPsiRepresentative & & psiStates . get ( trans . getColumn ( ) ) ) {
foundPsiRepresentative = true ;
psiRepresentative = trans . getColumn ( ) ;
STORM_LOG_DEBUG ( " Found psi representative " < < phiRepresentative ) ;
}
if ( foundPhiRepresentative & & foundPsiRepresentative ) {
eliminateState ( flexibleMatrix , oneStepProbabilities , * newInitialStates . begin ( ) , flexibleBackwardTransitions , missingStateRewards , false ) ;
// Now eliminate all chains of phi or psi states.
for ( auto phiState : phiStates ) {
// Only eliminate the state if it has a successor that is not itself.
auto const & currentRow = flexibleMatrix . getRow ( phiState ) ;
if ( currentRow . size ( ) = = 1 ) {
auto const & firstEntry = currentRow . front ( ) ;
if ( firstEntry . getColumn ( ) = = phiState ) {
break ;
}
}
eliminateState ( flexibleMatrix , oneStepProbabilities , phiState , flexibleBackwardTransitions , missingStateRewards , false , true , phiStates ) ;
}
for ( auto psiState : psiStates ) {
// Only eliminate the state if it has a successor that is not itself.
auto const & currentRow = flexibleMatrix . getRow ( psiState ) ;
if ( currentRow . size ( ) = = 1 ) {
auto const & firstEntry = currentRow . front ( ) ;
if ( firstEntry . getColumn ( ) = = psiState ) {
break ;
}
}
eliminateState ( flexibleMatrix , oneStepProbabilities , psiState , flexibleBackwardTransitions , missingStateRewards , false , true , psiStates ) ;
}
STORM_LOG_THROW ( foundPhiRepresentative , storm : : exceptions : : InvalidStateException , " Found no phi representative. " ) ;
STORM_LOG_THROW ( foundPsiRepresentative , storm : : exceptions : : InvalidStateException , " Found no psi representative. " ) ;
ValueType numerator = storm : : utility : : zero < ValueType > ( ) ;
ValueType denominator = storm : : utility : : zero < ValueType > ( ) ;
// Redirect all transitions to the phi states to their representative and do the same for the psi states.
for ( auto state : maybeStates ) {
std : : map < storm : : storage : : sparse : : state_type , ValueType > newSuccessors ;
for ( auto const & trans : submatrix . getRow ( state ) ) {
if ( phiStates . get ( trans . getColumn ( ) ) ) {
newSuccessors [ phiRepresentative ] + = trans . getValue ( ) ;
} else if ( psiStates . get ( trans . getColumn ( ) ) ) {
newSuccessors [ psiRepresentative ] + = trans . getValue ( ) ;
for ( auto const & trans1 : flexibleMatrix . getRow ( * newInitialStates . begin ( ) ) ) {
auto initialStateSuccessor = trans1 . getColumn ( ) ;
if ( phiStates . get ( initialStateSuccessor ) ) {
ValueType additiveTerm = storm : : utility : : zero < ValueType > ( ) ;
for ( auto const & trans2 : flexibleMatrix . getRow ( initialStateSuccessor ) ) {
STORM_LOG_ASSERT ( psiStates . get ( trans2 . getColumn ( ) ) , " Expected psi state. " ) ;
additiveTerm + = trans2 . getValue ( ) ;
}
additiveTerm * = trans1 . getValue ( ) ;
numerator + = additiveTerm ;
denominator + = additiveTerm ;
} else {
newSuccessors [ trans . getColumn ( ) ] + = trans . getValue ( ) ;
STORM_LOG_ASSERT ( psiStates . get ( initialStateSuccessor ) , " Expected psi state. " ) ;
denominator + = trans1 . getValue ( ) ;
ValueType additiveTerm = storm : : utility : : zero < ValueType > ( ) ;
for ( auto const & trans2 : flexibleMatrix . getRow ( initialStateSuccessor ) ) {
STORM_LOG_ASSERT ( phiStates . get ( trans2 . getColumn ( ) ) , " Expected phi state. " ) ;
additiveTerm + = trans2 . getValue ( ) ;
}
numerator + = trans1 . getValue ( ) * additiveTerm ;
}
std : : vector < storm : : storage : : MatrixEntry < storm : : storage : : sparse : : state_type , ValueType > > newTransitions ;
for ( auto const & stateValuePair : newSuccessors ) {
newTransitions . emplace_back ( stateValuePair ) ;
}
flexibleMatrix . getRow ( state ) = newTransitions ;
}
flexibleMatrix . print ( ) ;
return storm : : utility : : zero < ValueType > ( ) ;
return numerator / denominator ;
}
template < typename ValueType >
@ -533,7 +522,7 @@ namespace storm {
}
template < typename ValueType >
void SparseSccModelChecker < ValueType > : : eliminateState ( FlexibleSparseMatrix < ValueType > & matrix , std : : vector < ValueType > & oneStepProbabilities , uint_fast64_t state , FlexibleSparseMatrix < ValueType > & backwardTransitions , boost : : optional < std : : vector < ValueType > > & stateRewards ) {
void SparseSccModelChecker < ValueType > : : eliminateState ( FlexibleSparseMatrix < ValueType > & matrix , std : : vector < ValueType > & oneStepProbabilities , uint_fast64_t state , FlexibleSparseMatrix < ValueType > & backwardTransitions , boost : : optional < std : : vector < ValueType > > & stateRewards , bool removeForwardTransitions , bool constrained , storm : : storage : : BitVector const & predecessorConstraint ) {
auto eliminationStart = std : : chrono : : high_resolution_clock : : now ( ) ;
+ + counter ;
@ -591,6 +580,11 @@ namespace storm {
continue ;
}
// Skip the state if the elimination is constrained, but the predecessor is not in the constraint.
if ( constrained & & ! predecessorConstraint . get ( predecessor ) ) {
continue ;
}
// First, find the probability with which the predecessor can move to the current state, because
// the other probabilities need to be scaled with this factor.
typename FlexibleSparseMatrix < ValueType > : : row_type & predecessorForwardTransitions = matrix . getRow ( predecessor ) ;
@ -713,11 +707,18 @@ namespace storm {
}
STORM_LOG_DEBUG ( " Fixed predecessor lists of successor states. " ) ;
if ( removeForwardTransitions ) {
// Clear the eliminated row to reduce memory consumption.
currentStateSuccessors . clear ( ) ;
currentStateSuccessors . shrink_to_fit ( ) ;
}
if ( ! constrained ) {
// FIXME: is this safe? If the elimination is constrained, we might have to repair the predecessor
// relation.
currentStatePredecessors . clear ( ) ;
currentStatePredecessors . shrink_to_fit ( ) ;
}
auto eliminationEnd = std : : chrono : : high_resolution_clock : : now ( ) ;
auto eliminationTime = eliminationEnd - eliminationStart ;
dehnert
10 years ago