diff --git a/src/main/java/org/gcube/informationsystem/model/relation/consistsof/parthenos/inverse/PP49i_is_access_point_provided_by.java b/src/main/java/org/gcube/informationsystem/model/relation/consistsof/parthenos/inverse/PP49i_is_access_point_provided_by.java
new file mode 100644
index 0000000..ef82b96
--- /dev/null
+++ b/src/main/java/org/gcube/informationsystem/model/relation/consistsof/parthenos/inverse/PP49i_is_access_point_provided_by.java
@@ -0,0 +1,5 @@
+package org.gcube.informationsystem.model.relation.consistsof.parthenos.inverse;
+
+public interface PP49i_is_access_point_provided_by {
+	
+}
diff --git a/src/main/java/org/gcube/informationsystem/model/relation/consistsof/parthenos/inverse/PP50i_provides_access_to.java b/src/main/java/org/gcube/informationsystem/model/relation/consistsof/parthenos/inverse/PP50i_provides_access_to.java
new file mode 100644
index 0000000..f2926ed
--- /dev/null
+++ b/src/main/java/org/gcube/informationsystem/model/relation/consistsof/parthenos/inverse/PP50i_provides_access_to.java
@@ -0,0 +1,5 @@
+package org.gcube.informationsystem.model.relation.consistsof.parthenos.inverse;
+
+public interface PP50i_provides_access_to {
+
+}
diff --git a/src/main/java/org/gcube/informationsystem/model/relation/isrelatedto/parthenos/PP51_has_availability.java b/src/main/java/org/gcube/informationsystem/model/relation/isrelatedto/parthenos/PP51_has_availability.java
new file mode 100644
index 0000000..02f00ae
--- /dev/null
+++ b/src/main/java/org/gcube/informationsystem/model/relation/isrelatedto/parthenos/PP51_has_availability.java
@@ -0,0 +1,14 @@
+package org.gcube.informationsystem.model.relation.isrelatedto.parthenos;
+
+import org.gcube.informationsystem.model.entity.resource.parthenos.PE1_Service;
+import org.gcube.informationsystem.model.entity.resource.parthenos.PE39_Availability_Type;
+import org.gcube.informationsystem.model.relation.IsRelatedTo;
+
+/**
+ * @author Luca Frosini (ISTI - CNR)
+ */
+public interface PP51_has_availability
+	<Out extends PE1_Service, In extends PE39_Availability_Type> 
+		extends IsRelatedTo<Out, In>  {
+
+}
diff --git a/src/main/java/org/gcube/informationsystem/model/relation/isrelatedto/parthenos/inverse/PP50i_provides_access_to.java b/src/main/java/org/gcube/informationsystem/model/relation/isrelatedto/parthenos/inverse/PP50i_provides_access_to.java
deleted file mode 100644
index 4b0f3dd..0000000
--- a/src/main/java/org/gcube/informationsystem/model/relation/isrelatedto/parthenos/inverse/PP50i_provides_access_to.java
+++ /dev/null
@@ -1,5 +0,0 @@
-package org.gcube.informationsystem.model.relation.isrelatedto.parthenos.inverse;
-
-public interface PP50i_provides_access_to {
-
-}