diff --git a/src/Builtin/EcsGraphWorld.cs b/src/Builtin/EcsGraphWorld.cs
index ef7103a..468aec9 100644
--- a/src/Builtin/EcsGraphWorld.cs
+++ b/src/Builtin/EcsGraphWorld.cs
@@ -10,10 +10,10 @@ namespace DCFApixels.DragonECS
     [MetaID("DragonECS_ECC4CF479301897718600925B00A7DB4")]
     public sealed class EcsGraphWorld : EcsWorld, IInjectionUnit, IInjectionBlock
     {
-        public EcsGraphWorld() : base() { }
-        public EcsGraphWorld(EcsWorldConfig config = null, string name = null, short worldID = -1) : base(config, name == null ? "Default" : name, worldID) { }
-        public EcsGraphWorld(IConfigContainer configs, string name = null, short worldID = -1) : base(configs, name == null ? "Default" : name, worldID) { }
-
+        private const string DEFAULT_NAME = "Graph";
+        public EcsGraphWorld() : base(default(EcsWorldConfig), DEFAULT_NAME) { }
+        public EcsGraphWorld(EcsWorldConfig config = null, string name = null, short worldID = -1) : base(config, name == null ? DEFAULT_NAME : name, worldID) { }
+        public EcsGraphWorld(IConfigContainer configs, string name = null, short worldID = -1) : base(configs, name == null ? DEFAULT_NAME : name, worldID) { }
         void IInjectionUnit.InitInjectionNode(InjectionGraph nodes)
         {
             nodes.AddNode(this);
diff --git a/src/EntityGraph.cs b/src/EntityGraph.cs
index 0a040bb..12d9fb6 100644
--- a/src/EntityGraph.cs
+++ b/src/EntityGraph.cs
@@ -88,11 +88,29 @@ namespace DCFApixels.DragonECS
         {
             if (_matrix.TryGetValue(startEntityID, endEntityID, out int relEntityID))
             {
+#if DEBUG && DRAGONECS_DEEP_DEBUG
+                if(_graphWorld.IsUsed(relEntityID) == false)
+                {
+                    throw new InvalidOperationException();
+                }
+                var (s, e) = GetRelationStartEnd(relEntityID);
+                if (s != startEntityID || e != endEntityID)
+                {
+                    throw new InvalidOperationException();
+                }
+#endif
                 return relEntityID;
             }
             return NewRelationInternal(startEntityID, endEntityID);
         }
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public int GetOrNewRelationNoDirection(int entityID, int otherEntityID)
+        {
+            return GetOrNewRelation(
+                entityID < otherEntityID ? entityID : otherEntityID,
+                entityID > otherEntityID ? entityID : otherEntityID);
+        }
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public int GetOrNewInverseRelation(int relEntityID)
         {
 #if DEBUG || !DISABLE_DRAGONECS_ASSERT_CHEKS
@@ -106,6 +124,15 @@ namespace DCFApixels.DragonECS
         private int NewRelationInternal(int startEntityID, int endEntityID)
         {
             int relEntityID = _graphWorld.NewEntity();
+
+#if DEBUG && DRAGONECS_DEEP_DEBUG
+            var (s, e) = GetRelationStartEnd(relEntityID);
+            if (s != 0 || e != 0)
+            {
+                throw new InvalidOperationException();
+            }
+#endif
+
             _matrix.Add(startEntityID, endEntityID, relEntityID);
             _relEntityInfos[relEntityID] = new RelationInfo(startEntityID, endEntityID);
             _count++;