diff --git a/src/TensorFlowNET.Core/Binding.Util.cs b/src/TensorFlowNET.Core/Binding.Util.cs
index 9e97154c..6f6657af 100644
--- a/src/TensorFlowNET.Core/Binding.Util.cs
+++ b/src/TensorFlowNET.Core/Binding.Util.cs
@@ -32,8 +32,19 @@ namespace Tensorflow
     {
         public static T2 get<T1, T2>(this Dictionary<T1, T2> dict, T1 key)
             => key == null ? 
-                default(T2) : 
-            (dict.ContainsKey(key) ? dict[key] : default(T2));
+                default : 
+            (dict.ContainsKey(key) ? dict[key] : default);
+
+        public static void Update<T>(this IList<T> list, T element)
+        {
+            var index = list.IndexOf(element);
+            if (index < 0)
+                list.Add(element);
+            else
+            {
+                list[index] = element;
+            }
+        }
 
         public static void add<T>(this IList<T> list, T element)
             => list.Add(element);
diff --git a/src/TensorFlowNET.Core/Keras/BackendImpl.cs b/src/TensorFlowNET.Core/Keras/BackendImpl.cs
index 00e1587c..b765a48e 100644
--- a/src/TensorFlowNET.Core/Keras/BackendImpl.cs
+++ b/src/TensorFlowNET.Core/Keras/BackendImpl.cs
@@ -155,6 +155,16 @@ namespace Tensorflow.Keras
             return array_ops.pad(x, pattern);
         }
 
+        /// <summary>
+        /// Method to evaluate a tensor in eager or in a tf.function.
+        /// </summary>
+        /// <param name="outputs"></param>
+        /// <returns></returns>
+        public Tensor eval_in_eager_or_function(Tensor outputs)
+        {
+            throw new NotImplementedException("");
+        }
+
         public class _DummyEagerGraph
         { }
     }
diff --git a/src/TensorFlowNET.Core/Keras/Engine/Functional.cs b/src/TensorFlowNET.Core/Keras/Engine/Functional.cs
index ab83dc88..2b977dbc 100644
--- a/src/TensorFlowNET.Core/Keras/Engine/Functional.cs
+++ b/src/TensorFlowNET.Core/Keras/Engine/Functional.cs
@@ -1,7 +1,6 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
-using System.Security.Cryptography.X509Certificates;
 using System.Text;
 using Tensorflow.Keras.ArgsDefinition;
 using Tensorflow.Keras.Utils;
@@ -69,6 +68,11 @@ namespace Tensorflow.Keras.Engine
                 _input_coordinates.append(new KerasHistory(layer, node_index, tensor_index, x));
             }
         }
-       
+
+        protected override Tensors call(Tensors inputs, Tensor state = null, bool is_training = false)
+        {
+            return base.call(inputs, state, is_training);
+        }
+
     }
 }
diff --git a/src/TensorFlowNET.Core/Keras/Engine/KerasHistory.cs b/src/TensorFlowNET.Core/Keras/Engine/KerasHistory.cs
index 71b3aeda..05eb6fa7 100644
--- a/src/TensorFlowNET.Core/Keras/Engine/KerasHistory.cs
+++ b/src/TensorFlowNET.Core/Keras/Engine/KerasHistory.cs
@@ -20,8 +20,6 @@ namespace Tensorflow.Keras.Engine
             this.node_index = node_index;
             this.tensor_index = tensor_index;
             this.tensor = tensor;
-            Layer.KerasHistories.Add(this);
-            Console.WriteLine(tensor.name);
         }
 
         public void Deconstruct(out Layer layer, out int node_index, out int tensor_index)
diff --git a/src/TensorFlowNET.Core/Keras/Engine/Layer.cs b/src/TensorFlowNET.Core/Keras/Engine/Layer.cs
index 70d806f3..84e9e750 100644
--- a/src/TensorFlowNET.Core/Keras/Engine/Layer.cs
+++ b/src/TensorFlowNET.Core/Keras/Engine/Layer.cs
@@ -89,7 +89,6 @@ namespace Tensorflow.Keras.Engine
 
         ThreadLocal<CallContext> callContext;
         public CallContext CallContext => callContext.Value;
-        public static List<KerasHistory> KerasHistories = new List<KerasHistory>();
 
         public Layer(LayerArgs args)
         {
@@ -125,29 +124,16 @@ namespace Tensorflow.Keras.Engine
         }
 
         public void SetConnectivityMetadata(Tensors inputs, Tensors outputs)
-        {
-
-        }
+            => _set_connectivity_metadata_(inputs, outputs);
 
         private Tensors _set_connectivity_metadata_(Tensors inputs, Tensors outputs)
         {
-            /*var returnOutputs = new List<Tensor>();
-            foreach(var x in outputs)
-            {
-                if (inputs.Contains(x))
-                {
-
-                }
-                returnOutputs.Add(x);
-            }*/
-
             new Node(this, new NodeArgs
             {
                 InputTensors = inputs,
                 Outputs = outputs
             });
 
-            //_add_inbound_node(input_tensors: inputs, output_tensors: outputs);
             return outputs;
         }
 
diff --git a/src/TensorFlowNET.Core/Keras/Engine/Node.cs b/src/TensorFlowNET.Core/Keras/Engine/Node.cs
index 0ae84ac8..6c29850b 100644
--- a/src/TensorFlowNET.Core/Keras/Engine/Node.cs
+++ b/src/TensorFlowNET.Core/Keras/Engine/Node.cs
@@ -52,6 +52,8 @@ namespace Tensorflow.Keras.Engine
             layer.InboundNodes.Add(this);
             foreach (var kt in kerasInputs)
             {
+                if (kt.KerasHistory == null)
+                    continue;
                 var inbound_layer = kt.KerasHistory.layer;
                 if (inbound_layer != null)
                     inbound_layer.OutboundNodes.Add(this);
diff --git a/src/TensorFlowNET.Core/Keras/Engine/TensorFlowOpLayer.cs b/src/TensorFlowNET.Core/Keras/Engine/TensorFlowOpLayer.cs
index b39421ff..8e9725fa 100644
--- a/src/TensorFlowNET.Core/Keras/Engine/TensorFlowOpLayer.cs
+++ b/src/TensorFlowNET.Core/Keras/Engine/TensorFlowOpLayer.cs
@@ -8,12 +8,12 @@ namespace Tensorflow.Keras.Engine
     public class TensorFlowOpLayer : Layer
     {
         TensorFlowOpLayerArgs args;
-        string _TF_OP_LAYER_NAME_PREFIX = "";
+        static string TF_OP_LAYER_NAME_PREFIX = "tf_op_layer_";
 
         public TensorFlowOpLayer(TensorFlowOpLayerArgs args) 
             : base(new LayerArgs 
                 { 
-                    Name = "tf_op_layer_" + args.Name,
+                    Name = TF_OP_LAYER_NAME_PREFIX + args.Name,
                     Trainable = args.Trainable,
                     DType = args.DType,
                     Autocast = false
diff --git a/src/TensorFlowNET.Core/Keras/KerasApi.cs b/src/TensorFlowNET.Core/Keras/KerasApi.cs
index 5d08e8e8..43b46ebf 100644
--- a/src/TensorFlowNET.Core/Keras/KerasApi.cs
+++ b/src/TensorFlowNET.Core/Keras/KerasApi.cs
@@ -8,6 +8,7 @@ using Tensorflow.Keras.Datasets;
 using Tensorflow.Keras.Engine;
 using Tensorflow.Keras.Layers;
 using Tensorflow.Keras.Losses;
+using Tensorflow.Keras.Optimizers;
 using static Tensorflow.Binding;
 
 namespace Tensorflow
@@ -22,6 +23,7 @@ namespace Tensorflow
         public Activations activations { get; } = new Activations();
         public Preprocessing preprocessing { get; } = new Preprocessing();
         public BackendImpl backend { get; } = new BackendImpl();
+        public OptimizerApi optimizers { get; } = new OptimizerApi();
 
         public Sequential Sequential(List<Layer> layers = null,
                 string name = null)
diff --git a/src/TensorFlowNET.Core/Keras/Optimizers/OptimizerApi.cs b/src/TensorFlowNET.Core/Keras/Optimizers/OptimizerApi.cs
new file mode 100644
index 00000000..e521a827
--- /dev/null
+++ b/src/TensorFlowNET.Core/Keras/Optimizers/OptimizerApi.cs
@@ -0,0 +1,33 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace Tensorflow.Keras.Optimizers
+{
+    public class OptimizerApi
+    {
+        /// <summary>
+        /// Adam optimization is a stochastic gradient descent method that is based on
+        /// adaptive estimation of first-order and second-order moments.
+        /// </summary>
+        /// <param name="learning_rate"></param>
+        /// <param name="beta_1"></param>
+        /// <param name="beta_2"></param>
+        /// <param name="epsilon"></param>
+        /// <param name="amsgrad"></param>
+        /// <param name="name"></param>
+        /// <returns></returns>
+        public OptimizerV2 Adam(float learning_rate = 0.001f,
+                float beta_1 = 0.9f,
+                float beta_2 = 0.999f,
+                float epsilon = 1e-7f,
+                bool amsgrad = false,
+                string name = "Adam")
+            => new Adam(learning_rate: learning_rate,
+                beta_1: beta_1,
+                beta_2: beta_2,
+                epsilon: epsilon,
+                amsgrad: amsgrad,
+                name: name);
+    }
+}
diff --git a/src/TensorFlowNET.Core/Keras/Utils/base_layer_utils.cs b/src/TensorFlowNET.Core/Keras/Utils/base_layer_utils.cs
index b3ed60e6..ab246464 100644
--- a/src/TensorFlowNET.Core/Keras/Utils/base_layer_utils.cs
+++ b/src/TensorFlowNET.Core/Keras/Utils/base_layer_utils.cs
@@ -142,26 +142,39 @@ namespace Tensorflow.Keras.Utils
                             layer_inputs.Add(op_input);
                         else
                         {
+                            tf_with(ops.init_scope(), delegate
+                            {
 
-                        }
 
-                        // recursively
-                        CreateKerasHistoryHelper(layer_inputs, processed_ops, created_layers);
-                        var op_layer = new TensorFlowOpLayer(new TensorFlowOpLayerArgs
-                        {
-                            NodeDef = op.node_def,
-                            Name = op.name
-                        });
-                        created_layers.Add(op_layer);
-                        op_layer.SetConnectivityMetadata(layer_inputs, op.outputs);
+                            });
+                        }
                     }
+
+                    // recursively
+                    CreateKerasHistoryHelper(layer_inputs, processed_ops, created_layers);
+                    var op_layer = new TensorFlowOpLayer(new TensorFlowOpLayerArgs
+                    {
+                        NodeDef = op.node_def,
+                        Name = op.name
+                    });
+                    created_layers.Add(op_layer);
+                    op_layer.SetConnectivityMetadata(layer_inputs, op.outputs);
+                    processed_ops.Add(op);
                 }
             }
         }
 
+        // recusive
         static bool uses_keras_history(Tensor op_input)
         {
-            return Layer.KerasHistories.Any(x => x.tensor.name == op_input.name);
+            if (op_input.KerasHistory != null)
+                return true;
+
+            foreach (var input in op_input.op.inputs._inputs)
+                if (uses_keras_history(input))
+                    return true;
+
+            return false;
         }
     }
 }
diff --git a/src/TensorFlowNET.Core/Tensorflow.Binding.csproj b/src/TensorFlowNET.Core/Tensorflow.Binding.csproj
index 015edfb2..29a33837 100644
--- a/src/TensorFlowNET.Core/Tensorflow.Binding.csproj
+++ b/src/TensorFlowNET.Core/Tensorflow.Binding.csproj
@@ -29,7 +29,7 @@ https://tensorflownet.readthedocs.io</Description>
     <FileVersion>0.21.0.0</FileVersion>
     <PackageLicenseFile>LICENSE</PackageLicenseFile>
     <PackageRequireLicenseAcceptance>true</PackageRequireLicenseAcceptance>
-    <SignAssembly>false</SignAssembly>
+    <SignAssembly>true</SignAssembly>
     <AssemblyOriginatorKeyFile>Open.snk</AssemblyOriginatorKeyFile>
     <Platforms>AnyCPU;x64</Platforms>
   </PropertyGroup>