diff --git a/dmnverifierapi/src/test/java/de/unikoblenz/fgbks/base/utils/boundary/checker/CheckInContactTest.java b/dmnverifierapi/src/test/java/de/unikoblenz/fgbks/base/utils/boundary/checker/CheckInContactTest.java
index 741f2cadac14fdcc823b901cf2df128e7903b0e7..57928700f6c1eb60ae8cf54a73b8f45ceed1f79e 100644
--- a/dmnverifierapi/src/test/java/de/unikoblenz/fgbks/base/utils/boundary/checker/CheckInContactTest.java
+++ b/dmnverifierapi/src/test/java/de/unikoblenz/fgbks/base/utils/boundary/checker/CheckInContactTest.java
@@ -28,6 +28,8 @@ class CheckInContactTest extends AbstractCheckerTest {
     doNumCheck("[1..3]", "=0", false);
     doNumCheck("[1..3]", "=4", false);
     doNumCheck("[1..3]", "<=4", true);
+    doNumCheck("", "]1..3[", true);
+    doNumCheck("", "=2", true);
   }
 
   @Override
diff --git a/dmnverifierapi/src/test/java/de/unikoblenz/fgbks/base/utils/boundary/checker/CheckNotInContactTest.java b/dmnverifierapi/src/test/java/de/unikoblenz/fgbks/base/utils/boundary/checker/CheckNotInContactTest.java
index 7f100311735aaa32d47d71756a27235f50a5f8bf..12b2221852eb2a2d1410accc5f3efaebf4951a76 100644
--- a/dmnverifierapi/src/test/java/de/unikoblenz/fgbks/base/utils/boundary/checker/CheckNotInContactTest.java
+++ b/dmnverifierapi/src/test/java/de/unikoblenz/fgbks/base/utils/boundary/checker/CheckNotInContactTest.java
@@ -28,6 +28,8 @@ class CheckNotInContactTest extends AbstractCheckerTest {
     doNumCheck("[1..3]", "=0", true);
     doNumCheck("[1..3]", "=4", true);
     doNumCheck("[1..3]", "<=4", false);
+    doNumCheck("", "]1..3[", false);
+    doNumCheck("", "=2", false);
   }
 
   @Override
diff --git a/dmnverifierapi/src/test/java/de/unikoblenz/fgbks/base/utils/boundary/checker/CheckOverlapTest.java b/dmnverifierapi/src/test/java/de/unikoblenz/fgbks/base/utils/boundary/checker/CheckOverlapTest.java
index 85f93ac9b93f75bfc70646cde29fddbfc7475f9f..b4a334b7476b9de25ed03eac8ecc4a2253e0bc45 100644
--- a/dmnverifierapi/src/test/java/de/unikoblenz/fgbks/base/utils/boundary/checker/CheckOverlapTest.java
+++ b/dmnverifierapi/src/test/java/de/unikoblenz/fgbks/base/utils/boundary/checker/CheckOverlapTest.java
@@ -54,10 +54,12 @@ class CheckOverlapTest extends AbstractCheckerTest {
     doNumCheck("[1..3[", "[1..3[", false);
     doNumCheck("]1..3]", "]1..3]", false);
     doNumCheck("]1..3[", "]1..3[", false);
+    doNumCheck("]1..3[", "", false);
+    doNumCheck("=1", "", false);
   }
 
   @Override
   protected boolean checkBothWays() {
-    return false;
+    return true;
   }
 }
diff --git a/dmnverifierapi/src/test/java/de/unikoblenz/fgbks/base/utils/boundary/checker/CheckSubsumesTest.java b/dmnverifierapi/src/test/java/de/unikoblenz/fgbks/base/utils/boundary/checker/CheckSubsumesTest.java
index 1583d7b7058d7ba799b2dfe56668091109a89175..5293760d06ee9f08da2c4c29ab6de050cfd5874f 100644
--- a/dmnverifierapi/src/test/java/de/unikoblenz/fgbks/base/utils/boundary/checker/CheckSubsumesTest.java
+++ b/dmnverifierapi/src/test/java/de/unikoblenz/fgbks/base/utils/boundary/checker/CheckSubsumesTest.java
@@ -54,6 +54,10 @@ class CheckSubsumesTest extends AbstractCheckerTest {
     doNumCheck("[1..3[", "[1..3[", false);
     doNumCheck("]1..3]", "]1..3]", false);
     doNumCheck("]1..3[", "]1..3[", false);
+    doNumCheck("]1..3[", "", false);
+    doNumCheck("=1", "", false);
+    doNumCheck("", "]1..3[", true);
+    doNumCheck("", "=2", true);
   }
 
   @Override