diff --git a/src/TensorFlowNET.Core/APIs/c_api.cs b/src/TensorFlowNET.Core/APIs/c_api.cs
index fd5952c8..a983d033 100644
--- a/src/TensorFlowNET.Core/APIs/c_api.cs
+++ b/src/TensorFlowNET.Core/APIs/c_api.cs
@@ -25,6 +25,7 @@ namespace Tensorflow
     /// size_t* => ref uint
     /// void* => IntPtr
     /// string => IntPtr c_api.StringPiece(IntPtr)
+    /// unsigned char => byte
     /// </summary>
     public static partial class c_api
     {
diff --git a/src/TensorFlowNET.Core/Exceptions/ValueError.cs b/src/TensorFlowNET.Core/Exceptions/ValueError.cs
new file mode 100644
index 00000000..92955d27
--- /dev/null
+++ b/src/TensorFlowNET.Core/Exceptions/ValueError.cs
@@ -0,0 +1,19 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace Tensorflow
+{
+    public class ValueError : Exception
+    {
+        public ValueError() : base()
+        {
+
+        }
+
+        public ValueError(string message) : base(message)
+        {
+
+        }
+    }
+}
diff --git a/src/TensorFlowNET.Core/Graphs/Graph.cs b/src/TensorFlowNET.Core/Graphs/Graph.cs
index fcc335fc..b36480db 100644
--- a/src/TensorFlowNET.Core/Graphs/Graph.cs
+++ b/src/TensorFlowNET.Core/Graphs/Graph.cs
@@ -27,6 +27,11 @@ namespace Tensorflow
         public string _graph_key;
         public Status Status { get; }
 
+        /// <summary>
+        /// Arbitrary collections of objects.
+        /// </summary>
+        private Dictionary<string, object> _collections = new Dictionary<string, object>();
+
         public Graph()
         {
             _handle = c_api.TF_NewGraph();
@@ -86,6 +91,11 @@ namespace Tensorflow
             throw new Exception($"Can not convert a {typeof(T).Name} into a {types_str}.");
         }
 
+        public void add_to_collection(string name, object value)
+        {
+            _collections[name] = value;
+        }
+
         public unsafe Operation create_op(string op_type, List<Tensor> inputs, TF_DataType[] dtypes, 
             TF_DataType[] input_types = null, string name = "", 
             Dictionary<string, AttrValue> attrs = null, OpDef op_def = null)
@@ -221,6 +231,11 @@ namespace Tensorflow
             return _nodes_by_name.Values.Select(x => x).ToArray();
         }
 
+        public Dictionary<string, object> get_collection(string name)
+        {
+            return _collections;
+        }
+
         public void Dispose()
         {
             c_api.TF_DeleteGraph(_handle);
diff --git a/src/TensorFlowNET.Core/Train/Optimizer.cs b/src/TensorFlowNET.Core/Train/Optimizer.cs
index 83c2e4d9..e006eec9 100644
--- a/src/TensorFlowNET.Core/Train/Optimizer.cs
+++ b/src/TensorFlowNET.Core/Train/Optimizer.cs
@@ -49,6 +49,7 @@ namespace Tensorflow
                 
             }
 
+            var var_list = variables.trainable_variables();
             return null;
         }
     }
diff --git a/src/TensorFlowNET.Core/Tensors/RefVariable.cs b/src/TensorFlowNET.Core/Variables/RefVariable.cs
similarity index 95%
rename from src/TensorFlowNET.Core/Tensors/RefVariable.cs
rename to src/TensorFlowNET.Core/Variables/RefVariable.cs
index f65b8e9a..6f129767 100644
--- a/src/TensorFlowNET.Core/Tensors/RefVariable.cs
+++ b/src/TensorFlowNET.Core/Variables/RefVariable.cs
@@ -4,7 +4,7 @@ using System.Text;
 
 namespace Tensorflow
 {
-    public class RefVariable : Variable
+    public class RefVariable : VariableV1
     {
         public bool _in_graph_mode = true;
         public Tensor _initial_value;
diff --git a/src/TensorFlowNET.Core/Variables/VariableScope.cs b/src/TensorFlowNET.Core/Variables/VariableScope.cs
new file mode 100644
index 00000000..025660c8
--- /dev/null
+++ b/src/TensorFlowNET.Core/Variables/VariableScope.cs
@@ -0,0 +1,11 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace Tensorflow
+{
+    public class VariableScope
+    {
+        public bool? use_resource { get; set; }
+    }
+}
diff --git a/src/TensorFlowNET.Core/Variables/VariableSynchronization.cs b/src/TensorFlowNET.Core/Variables/VariableSynchronization.cs
new file mode 100644
index 00000000..9d184cff
--- /dev/null
+++ b/src/TensorFlowNET.Core/Variables/VariableSynchronization.cs
@@ -0,0 +1,14 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace Tensorflow
+{
+    public enum VariableSynchronization
+    {
+        AUTO = 0,
+        NONE = 1,
+        ON_WRITE = 2,
+        ON_READ = 3
+    }
+}
diff --git a/src/TensorFlowNET.Core/Tensors/Variable.cs b/src/TensorFlowNET.Core/Variables/VariableV1.cs
similarity index 81%
rename from src/TensorFlowNET.Core/Tensors/Variable.cs
rename to src/TensorFlowNET.Core/Variables/VariableV1.cs
index b8031490..efd866fd 100644
--- a/src/TensorFlowNET.Core/Tensors/Variable.cs
+++ b/src/TensorFlowNET.Core/Variables/VariableV1.cs
@@ -14,9 +14,9 @@ namespace Tensorflow
     /// the variable are fixed. The value can be changed using one of the assign methods.
     /// https://tensorflow.org/guide/variables
     /// </summary>
-    public class Variable
+    public class VariableV1
     {
-        public Variable(object initial_value, string name = "", TF_DataType trainable = TF_DataType.DtInvalid, bool validate_shape = true)
+        public VariableV1(object initial_value, string name = "", TF_DataType trainable = TF_DataType.DtInvalid, bool validate_shape = true)
         {
 
         }
diff --git a/src/TensorFlowNET.Core/Variables/_VariableScopeStore.cs b/src/TensorFlowNET.Core/Variables/_VariableScopeStore.cs
new file mode 100644
index 00000000..a7b3e3b5
--- /dev/null
+++ b/src/TensorFlowNET.Core/Variables/_VariableScopeStore.cs
@@ -0,0 +1,16 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace Tensorflow
+{
+    public class _VariableScopeStore
+    {
+        public VariableScope current_scope { get; set; }
+
+        public _VariableScopeStore()
+        {
+            current_scope = new VariableScope();
+        }
+    }
+}
diff --git a/src/TensorFlowNET.Core/Variables/variable_scope.py.cs b/src/TensorFlowNET.Core/Variables/variable_scope.py.cs
new file mode 100644
index 00000000..b794c0f1
--- /dev/null
+++ b/src/TensorFlowNET.Core/Variables/variable_scope.py.cs
@@ -0,0 +1,74 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace Tensorflow
+{
+    public class variable_scope
+    {
+        public static string _VARSCOPESTORE_KEY = "__varscope";
+        public static bool _DEFAULT_USE_RESOURCE = false;
+
+        public static RefVariable default_variable_creator(object initial_value, string name = "", TF_DataType dtype = TF_DataType.DtInvalid, bool ? use_resource = null, VariableSynchronization synchronization = VariableSynchronization.AUTO)
+        {
+            var trainable = _get_trainable_value(synchronization);
+            if (!use_resource.HasValue)
+            {
+                use_resource = get_variable_scope().use_resource;
+            }
+
+            if(!use_resource.HasValue)
+                use_resource = _DEFAULT_USE_RESOURCE;
+
+            if (use_resource.Value)
+            {
+                throw new NotImplementedException();
+            }
+            else
+            {
+                return new RefVariable(initial_value);
+            }
+        }
+
+        public static VariableScope get_variable_scope()
+        {
+            return get_variable_scope_store().current_scope;
+        }
+
+        public static _VariableScopeStore get_variable_scope_store()
+        {
+            var scope_store = ops.get_collection(_VARSCOPESTORE_KEY);
+            if (scope_store == null)
+            {
+                scope_store = new _VariableScopeStore();
+                ops.add_to_collection(_VARSCOPESTORE_KEY, scope_store);
+            }
+            else
+            {
+                // scope_store = scope_store[0];
+            }
+
+            return scope_store;
+        }
+
+        public static bool _get_trainable_value(VariableSynchronization synchronization, bool? trainable = null)
+        {
+            if(synchronization == VariableSynchronization.ON_READ)
+            {
+                if (trainable.Value)
+                    throw new ValueError("Synchronization value can be set to " +
+                        "VariableSynchronization.ON_READ only for non-trainable variables. " +
+                        "You have specified trainable=True and " +
+                        "synchronization=VariableSynchronization.ON_READ.");
+                else
+                    trainable = false;
+            }
+            else if (!trainable.HasValue)
+            {
+                trainable = true;
+            }
+
+            return trainable.Value;
+        }
+    }
+}
diff --git a/src/TensorFlowNET.Core/Variables/variables.py.cs b/src/TensorFlowNET.Core/Variables/variables.py.cs
new file mode 100644
index 00000000..9a2602b2
--- /dev/null
+++ b/src/TensorFlowNET.Core/Variables/variables.py.cs
@@ -0,0 +1,18 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace Tensorflow
+{
+    public class variables
+    {
+        /// <summary>
+        /// Returns all variables created with `trainable=True`
+        /// </summary>
+        /// <returns></returns>
+        public static object trainable_variables()
+        {
+            return ops.get_collection(ops.GraphKey.TRAINABLE_VARIABLES);
+        }
+    }
+}
diff --git a/src/TensorFlowNET.Core/ops.GraphKeys.py.cs b/src/TensorFlowNET.Core/ops.GraphKeys.py.cs
new file mode 100644
index 00000000..a7f03cf9
--- /dev/null
+++ b/src/TensorFlowNET.Core/ops.GraphKeys.py.cs
@@ -0,0 +1,26 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace Tensorflow
+{
+    public partial class ops
+    {
+        /// <summary>
+        /// Standard names to use for graph collections.
+        /// The standard library uses various well-known names to collect and
+        /// retrieve values associated with a graph. For example, the
+        /// `tf.Optimizer` subclasses default to optimizing the variables
+        /// collected under `tf.GraphKeys.TRAINABLE_VARIABLES` if none is
+        /// specified, but it is also possible to pass an explicit list of
+        /// variables.
+        /// </summary>
+        public static class GraphKey
+        {
+            /// <summary>
+            /// the subset of `Variable` objects that will be trained by an optimizer.
+            /// </summary>
+            public static string TRAINABLE_VARIABLES = "trainable_variables";
+        }
+    }
+}
diff --git a/src/TensorFlowNET.Core/Operations/ops.cs b/src/TensorFlowNET.Core/ops.py.cs
similarity index 89%
rename from src/TensorFlowNET.Core/Operations/ops.cs
rename to src/TensorFlowNET.Core/ops.py.cs
index 02b7ca11..a0dfc52a 100644
--- a/src/TensorFlowNET.Core/Operations/ops.cs
+++ b/src/TensorFlowNET.Core/ops.py.cs
@@ -10,8 +10,19 @@ using System.Linq;
 
 namespace Tensorflow
 {
-    public static class ops
+    public partial class ops
     {
+        public static void add_to_collection(string name, object value)
+        {
+            var graph = tf.get_default_graph();
+            graph.add_to_collection(name, value);
+        }
+
+        public static _VariableScopeStore get_collection(string key)
+        {
+            return null;// get_default_graph().get_collection(key);
+        }
+
         public static Graph get_default_graph()
         {
             return tf.Graph();
diff --git a/src/TensorFlowNET.Core/tf.cs b/src/TensorFlowNET.Core/tf.cs
index 2ed1e223..8c4d5611 100644
--- a/src/TensorFlowNET.Core/tf.cs
+++ b/src/TensorFlowNET.Core/tf.cs
@@ -22,7 +22,7 @@ namespace Tensorflow
 
         public static RefVariable Variable<T>(T data, string name = "", TF_DataType dtype = TF_DataType.DtInvalid)
         {
-            return new RefVariable(data, name, dtype);
+            return variable_scope.default_variable_creator(data, name: name, dtype: TF_DataType.DtInvalid);
         }
 
         public static unsafe Tensor placeholder(TF_DataType dtype, TensorShape shape = null)
diff --git a/test/TensorFlowNET.Examples/LinearRegression.cs b/test/TensorFlowNET.Examples/LinearRegression.cs
index ae303fe9..2dc2d297 100644
--- a/test/TensorFlowNET.Examples/LinearRegression.cs
+++ b/test/TensorFlowNET.Examples/LinearRegression.cs
@@ -43,18 +43,13 @@ namespace TensorFlowNET.Examples
             var sub = pred - Y;
             var pow = tf.pow(sub, 2);
 
-
-
-
-
-
-
             var reduce = tf.reduce_sum(pow);
             var cost = reduce / (2d * n_samples);
 
             // radient descent
             // Note, minimize() knows to modify W and b because Variable objects are trainable=True by default
-            var optimizer = tf.train.GradientDescentOptimizer(learning_rate).minimize(cost);
+            var optimizer = tf.train.GradientDescentOptimizer(learning_rate);
+            optimizer.minimize(cost);
         }
     }
 }