diff --git a/src/include/array/array_base.cc.h b/src/include/array/array_base.cc.h
index afb6c92..9fb0657 100644
--- a/src/include/array/array_base.cc.h
+++ b/src/include/array/array_base.cc.h
@@ -144,7 +144,7 @@ namespace CNORXZ
     {
 	CXZ_ASSERT(i.lex() < this->size(), "index out of range");
 	auto beg = this->begin();
-	//assertCompatible(i,beg);
+	//CXZ_ASSERT(false, "IMPLEMENT CHECKS!!");
 	// check further compatibility of index/range format!!!
 	auto ai = beg + i.lex();
 	return *ai;
@@ -185,14 +185,35 @@ namespace CNORXZ
 	return this->cend();
     }
     
-    /*
     template <typename T>
-    template <typename I, typename M>
-    ConstOperationRoot<T,I> CArrayBase<T>::operator()(const IndexPtr<I,M>& i) const
+    template <class I, typename M>
+    COpRoot<T,I> CArrayBase<T>::operator()(const IndexPtr<I,M>& i) const
     {
-	return ConstOperationRoot<T,I>();
+	return COpRoot<T,I>(*this, std::static_pointer_cast<I>(i));
+    }
+
+    template <typename T>
+    template <class I, SizeT L>
+    COpRoot<T,I> CArrayBase<T>::operator()(const LIndex<I,L>& i) const
+    {
+	return COpRoot<T,LIndex<I,L>>(*this, i);
+    }
+
+    template <typename T>
+    template <class I, typename M>
+    COpRoot<T,I> CArrayBase<T>::op(const IndexPtr<I,M>& i) const
+    {
+	CXZ_ASSERT(false, "IMPLEMENT CHECKS!!");
+	return COpRoot<T,I>(*this, std::static_pointer_cast<I>(i));
+    }
+
+    template <typename T>
+    template <class I, SizeT L>
+    COpRoot<T,I> CArrayBase<T>::op(const LIndex<I,L>& i) const
+    {
+	CXZ_ASSERT(false, "IMPLEMENT CHECKS!!");
+	return COpRoot<T,LIndex<I,L>>(*this, i);
     }
-    */
 
     /*****************
      *   ArrayBase   *
@@ -244,14 +265,35 @@ namespace CNORXZ
 	return iterator(this->data(), this->cend());
     }
 
-    /*
     template <typename T>
-    template <typename I, typename M>
-    OperationRoot<T,I> ArrayBase<T>::operator()(const IndexPtr<I,M>& i)
+    template <class I, typename M>
+    OpRoot<T,I> ArrayBase<T>::operator()(const IndexPtr<I,M>& i) const
     {
-	return OperationRoot<T,I>();
+	return OpRoot<T,I>(*this, std::static_pointer_cast<I>(i));
+    }
+
+    template <typename T>
+    template <class I, SizeT L>
+    OpRoot<T,I> ArrayBase<T>::operator()(const LIndex<I,L>& i) const
+    {
+	return OpRoot<T,LIndex<I,L>>(*this, i);
+    }
+
+    template <typename T>
+    template <class I, typename M>
+    OpRoot<T,I> ArrayBase<T>::op(const IndexPtr<I,M>& i) const
+    {
+	CXZ_ASSERT(false, "IMPLEMENT CHECKS!!");
+	return OpRoot<T,I>(*this, std::static_pointer_cast<I>(i));
+    }
+
+    template <typename T>
+    template <class I, SizeT L>
+    OpRoot<T,I> ArrayBase<T>::op(const LIndex<I,L>& i) const
+    {
+	CXZ_ASSERT(false, "IMPLEMENT CHECKS!!");
+	return OpRoot<T,LIndex<I,L>>(*this, i);
     }
-    */
 }
 
 #endif
diff --git a/src/include/array/array_base.h b/src/include/array/array_base.h
index 9be12c4..ae552cc 100644
--- a/src/include/array/array_base.h
+++ b/src/include/array/array_base.h
@@ -9,7 +9,7 @@
 
 #include "base/base.h"
 #include "aindex.h"
-//#include "operation/"
+#include "operation/op_types.h"
 
 namespace CNORXZ
 {
@@ -55,8 +55,17 @@ namespace CNORXZ
 
 	virtual bool isView() const = 0;
 
-	//template <typename I, typename M>
-	//ConstOperationRoot<T,I> operator()(const IndexPtr<I,M>& i) const;
+	template <class I, typename M>
+	COpRoot<T,I> operator()(const IndexPtr<I,M>& i) const;
+
+	template <class I, SizeT L>
+	COpRoot<T,I> operator()(const LIndex<I,L>& i) const;
+
+    	template <class I, typename M>
+	COpRoot<T,I> op(const IndexPtr<I,M>& i) const;
+
+	template <class I, SizeT L>
+	COpRoot<T,I> op(const LIndex<I,L>& i) const;
     };
 
     template <typename T>
@@ -93,9 +102,17 @@ namespace CNORXZ
 	virtual iterator begin();
 	virtual iterator end();
 	
-	//template <typename I, typename M>
-	//OperationRoot<T,I> operator()(const IndexPtr<I,M>& i);
+	template <class I, typename M>
+	OpRoot<T,I> operator()(const IndexPtr<I,M>& i) const;
 
+	template <class I, SizeT L>
+	OpRoot<T,I> operator()(const LIndex<I,L>& i) const;
+
+    	template <class I, typename M>
+	OpRoot<T,I> op(const IndexPtr<I,M>& i) const;
+
+	template <class I, SizeT L>
+	OpRoot<T,I> op(const LIndex<I,L>& i) const;
     };
 
 }
diff --git a/src/include/base/types.h b/src/include/base/types.h
index 2f004dd..8f6a1b8 100644
--- a/src/include/base/types.h
+++ b/src/include/base/types.h
@@ -209,8 +209,56 @@ namespace CNORXZ
     // there should be also a static analogue
 
     // definition: ranges/lindex.h
-    template <class Index>
+    template <class Index, SizeT L>
     class LIndex;
+
+    // definition: array/array_base.h
+    template <typename T>
+    class CArrayBase;
+
+    // definition: array/array_base.h
+    template <typename T>
+    class ArrayBase;
+
+    // definition: array/array.h
+    template <typename T>
+    class MArray;
+
+    // definition: array/slice.h
+    template <typename T>
+    class CSlice;
+
+    // definition: array/slice.h
+    template <typename T>
+    class Slice;
+
+    // definition: operation/op_types.h
+    template <class OpT>
+    class COpInterface;
+    
+    // definition: operation/op_types.h
+    template <class OpT>
+    class OpInterface;
+
+    // definition: operation/op_types.h
+    template <typename T, class IndexT>
+    class COpRoot;
+
+    // definition: operation/op_types.h
+    template <typename T, class IndexT>
+    class OpCont;
+
+    // definition: operation/op_types.h
+    template <typename T, class IndexT>
+    class OpRoot;
+
+    // definition: operation/op_types.h
+    template <class F, class... Ops>
+    class Operation;
+
+    // definition: operation/op_types.h
+    template <class CXpr>
+    class Contraction;
     
     /*********************
      *   derived types   *