Handle no change after verification iterations by re-guessing

This may lead to some testcases breaking. Needs further investigation
Handle only no change by re-guessing, instead of all other cases

src/storm/solver/helper/OptimisticValueIterationHelper.h

@@ -183,7 +183,7 @@ namespace storm {
                                 // Set lowerX to the upper bound candidate
                                 std::swap(lowerX, upperX);
                                 break;
-                            } else if (newUpperBoundAlwaysLowerEqual) {
+                            } else if (newUpperBoundAlwaysLowerEqual &! newUpperBoundAlwaysHigherEqual) {
                                 // All values moved down or stayed the same and we have a maximum difference of twice the requested precision
                                 // We can safely use twice the requested precision, as we calculate the center of both vectors
                                 bool reachedPrecision;
@@ -199,6 +199,9 @@ namespace storm {
                                     // From now on, we keep updating both bounds
                                     intervalIterationNeeded = true;
                                 }
+                            } else if (newUpperBoundAlwaysHigherEqual && newUpperBoundAlwaysLowerEqual) {
+                                // All values stayed the same. For safety we guess above this value again and check, if all values move down
+                                break;
                             }
                             // At this point, the old upper bounds (auxVector) are not needed anymore.