diff --git a/src/main/java/org/gcube/informationsystem/discovery/knowledge/ClassInformation.java b/src/main/java/org/gcube/informationsystem/discovery/knowledge/ClassInformation.java
index 22fb4c9..04b32f3 100644
--- a/src/main/java/org/gcube/informationsystem/discovery/knowledge/ClassInformation.java
+++ b/src/main/java/org/gcube/informationsystem/discovery/knowledge/ClassInformation.java
@@ -3,7 +3,6 @@ package org.gcube.informationsystem.discovery.knowledge;
 import java.util.LinkedHashSet;
 import java.util.Set;
 
-import org.gcube.informationsystem.base.reference.AccessType;
 import org.gcube.informationsystem.base.reference.Element;
 import org.gcube.informationsystem.tree.NodeInformation;
 import org.gcube.informationsystem.types.TypeMapper;
@@ -36,14 +35,4 @@ public class ClassInformation implements NodeInformation<Class<Element>> {
 		return ret;
 	}
 
-	@Override
-	public AccessType getAccessType(Class<Element> clz) {
-		return AccessType.getAccessType(clz);
-	}
-
-	@Override
-	public Class<Element> getRoot(AccessType accessType) {
-		return accessType.getTypeClass();
-	}
-
 }
diff --git a/src/main/java/org/gcube/informationsystem/knowledge/ModelKnowledge.java b/src/main/java/org/gcube/informationsystem/knowledge/ModelKnowledge.java
index d40f68b..e17b5b7 100644
--- a/src/main/java/org/gcube/informationsystem/knowledge/ModelKnowledge.java
+++ b/src/main/java/org/gcube/informationsystem/knowledge/ModelKnowledge.java
@@ -18,7 +18,6 @@ import org.gcube.informationsystem.model.reference.entities.Resource;
 import org.gcube.informationsystem.model.reference.relations.ConsistsOf;
 import org.gcube.informationsystem.model.reference.relations.IsRelatedTo;
 import org.gcube.informationsystem.model.reference.relations.Relation;
-import org.gcube.informationsystem.tree.NodeInformation;
 import org.gcube.informationsystem.tree.Tree;
 import org.gcube.informationsystem.types.PropertyTypeName;
 import org.gcube.informationsystem.types.TypeMapper;
@@ -36,18 +35,18 @@ import org.slf4j.LoggerFactory;
 /**
  * @author Luca Frosini (ISTI - CNR)
  */
-public class ModelKnowledge<T, NI extends NodeInformation<T>> {
+public class ModelKnowledge<T, TI extends TypeInformation<T>> {
 	
 	private static final Logger logger = LoggerFactory.getLogger(ModelKnowledge.class);
 	
-	protected NI nodeInformation;
+	protected TI typeInformation;
 	protected Map<AccessType, Tree<T>> trees;
 	
 	protected UsageKnowledge<Entry<String,PropertyDefinition>> propertyUsage;
 	protected Map<AccessType, UsageKnowledge<LinkedEntity>> erTypesUsage;
 
-	public ModelKnowledge(NI nodeInformation) {
-		this.nodeInformation = nodeInformation;
+	public ModelKnowledge(TI typeInformation) {
+		this.typeInformation = typeInformation;
 		reset();
 	}
 	
@@ -58,9 +57,9 @@ public class ModelKnowledge<T, NI extends NodeInformation<T>> {
 		
 		AccessType[] modelTypes = AccessType.getModelTypes();
 		for(AccessType accessType : modelTypes) {
-			T t = nodeInformation.getRoot(accessType);
+			T t = typeInformation.getRoot(accessType);
 			
-			Tree<T> tree = new Tree<>(t, nodeInformation);
+			Tree<T> tree = new Tree<>(t, typeInformation);
 			trees.put(accessType, tree);
 			
 			if(accessType == AccessType.PROPERTY) {
@@ -104,7 +103,7 @@ public class ModelKnowledge<T, NI extends NodeInformation<T>> {
 		if(properties==null || properties.size()==0) {
 			return;
 		}
-		String typeName = nodeInformation.getIdentifier(t);
+		String typeName = typeInformation.getIdentifier(t);
 		for(PropertyDefinition propertyDefinition : properties) {
 			PropertyTypeName propertyTypeName = ((PropertyDefinitionImpl) propertyDefinition).getPropertyTypeName();
 			if(propertyTypeName.isGenericType()) {
@@ -133,7 +132,7 @@ public class ModelKnowledge<T, NI extends NodeInformation<T>> {
 		Set<T> toRetry = new HashSet<>();
 		
 		for(T t : types) {
-			logger.trace("Going to add {}", nodeInformation.getIdentifier(t));
+			logger.trace("Going to add {}", typeInformation.getIdentifier(t));
 			try {
 				addType(t);
 			}catch (RuntimeException e) {
@@ -147,8 +146,8 @@ public class ModelKnowledge<T, NI extends NodeInformation<T>> {
 	}
 	
 	public void addType(T t) {
-		AccessType accessType = nodeInformation.getAccessType(t);
-		String typeName = nodeInformation.getIdentifier(t);
+		AccessType accessType = typeInformation.getAccessType(t);
+		String typeName = typeInformation.getIdentifier(t);
 		
 		Tree<T> tree = trees.get(accessType);
 		tree.addNode(t);
diff --git a/src/main/java/org/gcube/informationsystem/knowledge/TypeInformation.java b/src/main/java/org/gcube/informationsystem/knowledge/TypeInformation.java
index ce46a9d..5720ac9 100644
--- a/src/main/java/org/gcube/informationsystem/knowledge/TypeInformation.java
+++ b/src/main/java/org/gcube/informationsystem/knowledge/TypeInformation.java
@@ -1,40 +1,12 @@
 package org.gcube.informationsystem.knowledge;
 
-import java.util.LinkedHashSet;
-import java.util.Set;
-
 import org.gcube.informationsystem.base.reference.AccessType;
 import org.gcube.informationsystem.tree.NodeInformation;
-import org.gcube.informationsystem.types.TypeMapper;
-import org.gcube.informationsystem.types.reference.Type;
-
-/**
- * @author Luca Frosini (ISTI - CNR)
- */
-public class TypeInformation implements NodeInformation<Type> {
-
-	@Override
-	public String getIdentifier(Type type) {
-		return type.getName();
-	}
-
-	@Override
-	public Set<String> getParentIdentifiers(Type root, Type type) {
-		if(type.getName().compareTo(root.getName())==0) {
-			return new LinkedHashSet<>();
-		}
-		
-		return type.getExtendedTypes();
-	}
-
-	@Override
-	public AccessType getAccessType(Type type) {
-		return type.getAccessType();
-	}
-
-	@Override
-	public Type getRoot(AccessType accessType) {
-		return TypeMapper.createTypeDefinition(accessType.getTypeClass());
-	}
 
+public interface TypeInformation<T> extends NodeInformation<T> {
+	
+	public AccessType getAccessType(T t);
+	
+	public T getRoot(AccessType accessType);
+	
 }
diff --git a/src/main/java/org/gcube/informationsystem/tree/NodeInformation.java b/src/main/java/org/gcube/informationsystem/tree/NodeInformation.java
index 610e2de..ca1ba26 100644
--- a/src/main/java/org/gcube/informationsystem/tree/NodeInformation.java
+++ b/src/main/java/org/gcube/informationsystem/tree/NodeInformation.java
@@ -2,16 +2,10 @@ package org.gcube.informationsystem.tree;
 
 import java.util.Set;
 
-import org.gcube.informationsystem.base.reference.AccessType;
-
 public interface NodeInformation<T> {
 
 	public String getIdentifier(T t);
 	
 	public Set<String> getParentIdentifiers(T root, T t);
 	
-	public AccessType getAccessType(T t);
-	
-	public T getRoot(AccessType accessType);
-	
 }
diff --git a/src/main/java/org/gcube/informationsystem/types/knowledge/TypeInformation.java b/src/main/java/org/gcube/informationsystem/types/knowledge/TypeInformation.java
new file mode 100644
index 0000000..42cbc5b
--- /dev/null
+++ b/src/main/java/org/gcube/informationsystem/types/knowledge/TypeInformation.java
@@ -0,0 +1,39 @@
+package org.gcube.informationsystem.types.knowledge;
+
+import java.util.LinkedHashSet;
+import java.util.Set;
+
+import org.gcube.informationsystem.base.reference.AccessType;
+import org.gcube.informationsystem.types.TypeMapper;
+import org.gcube.informationsystem.types.reference.Type;
+
+/**
+ * @author Luca Frosini (ISTI - CNR)
+ */
+public class TypeInformation implements org.gcube.informationsystem.knowledge.TypeInformation<Type> {
+
+	@Override
+	public String getIdentifier(Type type) {
+		return type.getName();
+	}
+
+	@Override
+	public Set<String> getParentIdentifiers(Type root, Type type) {
+		if(type.getName().compareTo(root.getName())==0) {
+			return new LinkedHashSet<>();
+		}
+		
+		return type.getExtendedTypes();
+	}
+
+	@Override
+	public AccessType getAccessType(Type type) {
+		return type.getAccessType();
+	}
+
+	@Override
+	public Type getRoot(AccessType accessType) {
+		return TypeMapper.createTypeDefinition(accessType.getTypeClass());
+	}
+
+}
diff --git a/src/test/java/org/gcube/informationsystem/knowledge/ModelKnowledgeTest.java b/src/test/java/org/gcube/informationsystem/knowledge/ModelKnowledgeTest.java
index bceb722..eee74e0 100644
--- a/src/test/java/org/gcube/informationsystem/knowledge/ModelKnowledgeTest.java
+++ b/src/test/java/org/gcube/informationsystem/knowledge/ModelKnowledgeTest.java
@@ -15,6 +15,7 @@ import org.gcube.informationsystem.tree.Node;
 import org.gcube.informationsystem.tree.NodeElaborator;
 import org.gcube.informationsystem.tree.Tree;
 import org.gcube.informationsystem.types.TypeMapper;
+import org.gcube.informationsystem.types.knowledge.TypeInformation;
 import org.gcube.informationsystem.types.reference.Type;
 import org.gcube.informationsystem.types.reference.properties.LinkedEntity;
 import org.gcube.informationsystem.types.reference.properties.PropertyDefinition;