Fixed problem in MaximalEndComponents

Former-commit-id: 950b9cfdfa

src/modelchecker/csl/helper/SparseMarkovAutomatonCslHelper.cpp

@@ -407,11 +407,14 @@ namespace storm {
                         infinityStates = storm::storage::BitVector(numberOfStates);
                     }
                 }
-                
                 // Now we identify the states for which values need to be computed.
                 storm::storage::BitVector maybeStates = ~(goalStates | infinityStates);
 
-                // Then, we can eliminate the rows and columns for all states whose values are already known to be 0.
+                // Create resulting vector.
+                std::vector<ValueType> result(numberOfStates);
+                
+                if (!maybeStates.empty()) {
+                    // Then, we can eliminate the rows and columns for all states whose values are already known.
                     std::vector<ValueType> x(maybeStates.getNumberOfSetBits());
                     storm::storage::SparseMatrix<ValueType> submatrix = transitionMatrix.getSubmatrix(true, maybeStates, maybeStates);
                     
@@ -429,11 +432,10 @@ namespace storm {
                     std::unique_ptr<storm::solver::MinMaxLinearEquationSolver<ValueType>> solver = minMaxLinearEquationSolverFactory.create(submatrix);
                     solver->solveEquationSystem(dir, x, b);
                     
-                // Create resulting vector.
-                std::vector<ValueType> result(numberOfStates);
-                
                     // Set values of resulting vector according to previous result and return the result.
                     storm::utility::vector::setVectorValues<ValueType>(result, maybeStates, x);
+                }
+
                 storm::utility::vector::setVectorValues(result, goalStates, storm::utility::zero<ValueType>());
                 storm::utility::vector::setVectorValues(result, infinityStates, storm::utility::infinity<ValueType>());
                 

src/storage/Decomposition.cpp

@@ -41,6 +41,11 @@ namespace storm {
             return blocks.size();
         }
         
+        template <typename BlockType>
+        bool Decomposition<BlockType>::empty() const {
+            return blocks.empty();
+        }
+        
         template <typename BlockType>
         typename Decomposition<BlockType>::iterator Decomposition<BlockType>::begin() {
             return blocks.begin();

src/storage/Decomposition.h

@@ -63,6 +63,13 @@ namespace storm {
              */
             std::size_t size() const;
             
+            /*!
+             * Checks if the decomposition is empty.
+             *
+             * @return True, if the decomposition is empty.
+             */
+            bool empty() const;
+            
             /*!
              * Retrieves an iterator that points to the first block of this decomposition.
              *

src/storage/MaximalEndComponentDecomposition.cpp

@@ -86,6 +86,9 @@ namespace storm {
                 mecChanged |= sccs.size() > 1 || (sccs.size() > 0 && sccs[0].size() < mec.size());
                 
                 // Check for each of the SCCs whether there is at least one action for each state that does not leave the SCC.
+                if (sccs.empty()) {
+                    mecChanged = true;
+                } else {
                     for (auto& scc : sccs) {
                         statesToCheck.set(scc.begin(), scc.end());
                         
@@ -133,6 +136,7 @@ namespace storm {
                             }
                         }
                     }
+                }
                 
                 // If the MEC changed, we delete it from the list of MECs and append the possible new MEC candidates to
                 // the list instead.