diff --git a/t.cc b/t.cc
index fa24f7a..a865b14 100644
--- a/t.cc
+++ b/t.cc
@@ -3243,7 +3243,7 @@ cout <<epsilon.data;
 cout <<epsilon;
 }
 
-if(1)
+if(0)
 {
 int n=3;
 NRVec<INDEXGROUP> s(4);
@@ -3270,5 +3270,28 @@ for(int i=0; i<n; ++i)
 }
 
 
+if(1)
+{
+int n=5;
+INDEXGROUP g;
+g.number=4;
+g.symmetry= -1;
+g.offset=0;
+g.range=n;
+
+Tensor<double> e(g);
+e.randomize(1.);
+Tensor<double> eu = e.unwind_index(0,1);
+
+for(int i=0; i<n; ++i)
+        for(int j=0; j<n; ++j)
+                for(int k=0; k<n; ++k)
+                        for(int l=0; l<n; ++l)
+                                {
+				if(e(i,j,k,l)!=eu(j,i,k,l)) laerror("error in unwind_index");
+				}
+cout <<e;
+cout <<eu;
+}
 
 }
diff --git a/tensor.cc b/tensor.cc
index 7b9d44c..8e3fbb4 100644
--- a/tensor.cc
+++ b/tensor.cc
@@ -521,6 +521,8 @@ loopovergroups(*this,shape.size()-1,&pp,I,callback);
 const NRPerm<int> *help_p;
 template<typename T> 
 Tensor<T> *help_t;
+template<typename T>
+const Tensor<T> *help_tt;
 
 template<typename T>
 static void permutecallback(const GROUPINDEX &I, T *v)
@@ -551,6 +553,94 @@ return r;
 }
 
 
+FLATINDEX superindex2flat(const SUPERINDEX &I)
+{
+int rank=0;
+for(int i=0; i<I.size(); ++i) rank += I[i].size();
+FLATINDEX J(rank);
+int ii=0;
+for(int i=0; i<I.size(); ++i)
+	{
+	for(int j=0; j<I[i].size(); ++j) J[ii++] = I[i][j];
+	}
+return J;
+}
+
+
+template<typename T>
+static void unwind_callback(const SUPERINDEX &I, T *v)
+{
+FLATINDEX J = superindex2flat(I);
+FLATINDEX JP = J.permuted(*help_p,true);
+//std::cout <<"TEST unwind_callback: from "<<JP<<" TO "<<J<<std::endl;
+*v = (*help_tt<T>)(JP); //rhs operator() generates the redundant elements for the unwinded lhs tensor
+}
+
+
+
+template<typename T>
+Tensor<T> Tensor<T>::unwind_index(int group, int index) const
+{
+if(group<0||group>=shape.size()) laerror("wrong group number in unwind_index");
+if(index<0||index>=shape[group].number)  laerror("wrong index number in unwind_index");
+if(shape[group].number==1) //single index in the group
+	{
+	if(group==0) return *this; //is already the least significant group
+	NRPerm<int> p(shape.size());
+	p[1]= 1+group;
+	int ii=1;
+	for(int i=2; i<=shape.size(); ++i) 
+		{
+		p[i]=ii++;
+		if(ii==1+group) ii++; //skip this
+		}
+	if(!p.is_valid()) laerror("internal error in unwind_index");
+	return permute_index_groups(p);
+	}
+
+//general case - recalculate the shape and allocate the new tensor
+NRVec<indexgroup> newshape(shape.size()+1);
+newshape[0].number=1;
+newshape[0].symmetry=0;
+newshape[0].range=shape[group].range;
+#ifndef LA_TENSOR_ZERO_OFFSET
+newshape[0].offset = shape[group].offset;
+#endif
+int flatindex=0; //(group,index) in flat form
+for(int i=0; i<shape.size(); ++i)
+	{
+	newshape[i+1] = shape[i];
+	if(i==group)
+		{
+		--newshape[i+1].number;
+		flatindex += index;
+		}
+	else flatindex += shape[i].number;
+	}
+
+Tensor<T> r(newshape);
+if(r.rank()!=rank()) laerror("internal error 2 in unwind_index");
+
+//compute the corresponding permutation of FLATINDEX for use in the callback
+NRPerm<int> indexperm(rank());
+indexperm[1]=flatindex+1;
+int ii=1;
+for(int i=2; i<=rank(); ++i) 
+	{
+	indexperm[i] = ii++;
+	if(ii==flatindex+1) ii++; //skip this
+	}
+if(!indexperm.is_valid()) laerror("internal error 3 in unwind_index");
+
+//loop recursively and do the unwinding
+help_tt<T> = this;
+help_p = &indexperm;
+r.loopover(unwind_callback);
+return r;
+}
+
+
+
 
 template class Tensor<double>;
 template class Tensor<std::complex<double> >;
diff --git a/tensor.h b/tensor.h
index 12cd254..d4931da 100644
--- a/tensor.h
+++ b/tensor.h
@@ -62,9 +62,9 @@ typedef int LA_largeindex;
 typedef class indexgroup {
 public:
 int number; //number of indices
-int symmetry; //-1 0 or 1
+int symmetry; //-1 0 or 1, later 2 for hermitian and -2 for antihermitian? - would need change in operator() and Signedpointer
 #ifdef LA_TENSOR_ZERO_OFFSET
-static const LA_index offset = 0; //compiler can optimiza away some computations 
+static const LA_index offset = 0; //compiler can optimize away some computations 
 #else
 LA_index offset; //indices start at a general offset
 #endif
@@ -99,6 +99,7 @@ typedef NRVec<LA_index> FLATINDEX; //all indices but in a single vector
 typedef NRVec<NRVec<LA_index> > SUPERINDEX; //all indices in the INDEXGROUP structure
 typedef NRVec<LA_largeindex> GROUPINDEX; //set of indices in the symmetry groups
 
+FLATINDEX superindex2flat(const SUPERINDEX &I);
 
 template<typename T>
 class Tensor {
@@ -132,11 +133,11 @@ public:
 	LA_largeindex size() const {return data.size();};
 	void copyonwrite() {shape.copyonwrite(); groupsizes.copyonwrite(); cumsizes.copyonwrite(); data.copyonwrite();};
         inline Signedpointer<T> lhs(const SUPERINDEX &I) {int sign; LA_largeindex i=index(&sign,I); return Signedpointer<T>(&data[i],sign);};
-	inline T operator()(const SUPERINDEX &I) {int sign; LA_largeindex i=index(&sign,I); if(sign==0) return 0; return sign>0 ?data[i] : -data[i];};
+	inline T operator()(const SUPERINDEX &I) const {int sign; LA_largeindex i=index(&sign,I); if(sign==0) return 0; return sign>0 ?data[i] : -data[i];};
         inline Signedpointer<T> lhs(const FLATINDEX &I) {int sign; LA_largeindex i=index(&sign,I); return Signedpointer<T>(&data[i],sign);};
-        inline T operator()(const FLATINDEX &I) {int sign; LA_largeindex i=index(&sign,I); if(sign==0) return 0; return sign>0 ?data[i] : -data[i];};
+        inline T operator()(const FLATINDEX &I) const {int sign; LA_largeindex i=index(&sign,I); if(sign==0) return 0; return sign>0 ?data[i] : -data[i];};
         inline Signedpointer<T> lhs(LA_index i1...) {va_list args; int sign; LA_largeindex i; va_start(args,i1); i= vindex(&sign, i1,args);  return Signedpointer<T>(&data[i],sign); };
-        inline T operator()(LA_index i1...) {va_list args; ; int sign; LA_largeindex i; va_start(args,i1);  i= vindex(&sign, i1,args); if(sign==0) return 0; return sign>0 ?data[i] : -data[i];};
+        inline T operator()(LA_index i1...) const {va_list args; ; int sign; LA_largeindex i; va_start(args,i1);  i= vindex(&sign, i1,args); if(sign==0) return 0; return sign>0 ?data[i] : -data[i];};
 	
 	inline Tensor& operator=(const Tensor &rhs) {myrank=rhs.myrank; shape=rhs.shape; groupsizes=rhs.groupsizes; cumsizes=rhs.cumsizes; data=rhs.data; return *this;};
 
@@ -177,13 +178,11 @@ public:
 	void grouploopover(void (*callback)(const GROUPINDEX &, T *)); //loop over all elements disregarding the internal structure of index groups
 
 	Tensor permute_index_groups(const NRPerm<int> &p) const; //rearrange the tensor storage permuting index groups as a whole
+	Tensor unwind_index(int group, int index) const; //separate an index from a group and expand it to full range as the least significant one
 
-	//@@@TODO - unwinding to full size in a specified index
-	//@@@contraction by a whole index group or by individual single index
-	//@@@ general antisymmetrization operator Kucharski style
-	//@@@TODO - contractions - basic and efficient? first contraction in a single index; between a given group+index in group at each tensor
-	//@@@outer product and product with a contraction
-	//@@@@symmetrize a group, antisymmetrize a group, expand a (anti)symmetric grtoup - obecne symmetry change krome +1 na -1 vse mozne
+	//@@@ general antisymmetrization operator Kucharski style - or that will be left to a code generator?
+	//@@@symmetrize a group, antisymmetrize a group, expand a (anti)symmetric group - obecne symmetry change krome +1 na -1 vse mozne
+	//@@@contraction
 };