From c07734d80a0d7c0099acc870a71452b23e371e7c Mon Sep 17 00:00:00 2001
From: Jan Erik Karuc <jan.karuc@rwth-aachen.de>
Date: Fri, 3 Apr 2020 10:39:27 +0200
Subject: [PATCH] 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 | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/storm/solver/helper/OptimisticValueIterationHelper.h b/src/storm/solver/helper/OptimisticValueIterationHelper.h
index 1adb29b38..4cfe6c012 100644
--- a/src/storm/solver/helper/OptimisticValueIterationHelper.h
+++ b/src/storm/solver/helper/OptimisticValueIterationHelper.h
@@ -175,7 +175,7 @@ namespace storm {
                                     newUpperBoundAlwaysLowerEqual = false;
                                 }
                             }
-                            if (newUpperBoundAlwaysHigherEqual & !newUpperBoundAlwaysLowerEqual) {
+                            if (newUpperBoundAlwaysHigherEqual &! newUpperBoundAlwaysLowerEqual) {
                                 // All values moved up or stayed the same (but are not the same)
                                 // That means the guess for an upper bound is actually a lower bound
                                 iterationPrecision = oviinternal::updateIterationPrecision(env, *auxVector, *upperX, relative, relevantValues);
@@ -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.