diff --git a/triqs/gfs/gf.hpp b/triqs/gfs/gf.hpp
index d35adfe6..820d1840 100644
--- a/triqs/gfs/gf.hpp
+++ b/triqs/gfs/gf.hpp
@@ -64,6 +64,8 @@ namespace triqs { namespace gfs {
   // This trait contains functions to read/write in hdf5 files. Can be specialized for some descriptor (Cf block)
   template <typename Variable, typename Target, typename Opt> struct h5_name; // value is a const char *
 
+  template<typename Variable, typename Opt> struct h5_name<Variable,scalar_valued,Opt>      { static std::string invoke(){ return h5_name<Variable,matrix_valued,Opt>::invoke() + "_s";}};
+  
   template <typename Variable, typename Target, typename Opt> struct h5_ops { 
    template<typename DataType, typename GF> static void write(h5::group g, std::string const & s, DataType const & data, GF const &) { h5_write(g,"data",data); }
    template<typename DataType, typename GF> static void read (h5::group g, std::string const & s, DataType & data, GF const &) { h5_read(g,"data",data);}
@@ -248,7 +250,7 @@ namespace triqs { namespace gfs {
 
     //----------------------------- HDF5 -----------------------------
 
-    friend std::string get_triqs_hdf5_data_scheme(gf_impl const & g) { return gfs_implementation::h5_name<Variable,Target,Opt>::invoke();}
+    friend std::string get_triqs_hdf5_data_scheme(gf_impl const & g) { return "Gf" + gfs_implementation::h5_name<Variable,Target,Opt>::invoke();}
 
     /// Write into HDF5
     friend void h5_write (h5::group fg, std::string subgroup_name, gf_impl const & g) {
@@ -407,7 +409,15 @@ namespace triqs { namespace gfs {
    static_assert(std::is_same<Target,matrix_valued>::value, "slice_target only for matrix_valued GF's");
    using arrays::range;
    auto sg=slice_target (g.singularity(),range(args,args+1)...);
-   return gf_view<Variable,scalar_valued,Opt>(g.mesh(), g.data()(range(), args... ), sg , g.symmetry());
+   return gf_view<Variable,scalar_valued,Opt>(g.mesh(), g.data()(range(), args... ), sg, g.symmetry());
+  }
+
+  // a scalar_valued gf can be viewed as a 1x1 matrix
+  template<typename Variable, typename Opt, bool V, typename... Args>
+  gf_view<Variable,matrix_valued,Opt> reinterpret_scalar_valued_gf_as_matrix_valued (gf_impl<Variable,scalar_valued,Opt,V> const & g) {
+   typedef arrays::array_view<typename gfs_implementation::data_proxy<Variable,matrix_valued,Opt>::storage_t::value_type,3> a_t;
+   auto a = a_t {typename a_t::indexmap_type (arrays::mini_vector<size_t,3>(g.data().shape()[0],1,1)), g.data().storage()};
+   return gf_view<Variable,matrix_valued,Opt>(g.mesh(), a, g.singularity(), g.symmetry());
   }
 
  /*
diff --git a/triqs/gfs/imfreq.hpp b/triqs/gfs/imfreq.hpp
index c680f88e..535e4bcd 100644
--- a/triqs/gfs/imfreq.hpp
+++ b/triqs/gfs/imfreq.hpp
@@ -47,8 +47,7 @@ namespace triqs { namespace gfs {
   template<typename Opt> struct singularity<imfreq,scalar_valued,Opt>  { typedef local::tail type;};
   
   //h5 name
-  template<typename Opt> struct h5_name<imfreq,matrix_valued,Opt>      { static std::string invoke(){ return "GfImFreq";}};
-  template<typename Opt> struct h5_name<imfreq,scalar_valued,Opt>      { static std::string invoke(){ return "GfImFreq_s";}};
+  template<typename Opt> struct h5_name<imfreq,matrix_valued,Opt>      { static std::string invoke(){ return "ImFreq";}};
 
   /// ---------------------------  evaluator ---------------------------------
   template<typename Opt, typename Target>
diff --git a/triqs/gfs/imtime.hpp b/triqs/gfs/imtime.hpp
index 4a160a9c..30b46aea 100644
--- a/triqs/gfs/imtime.hpp
+++ b/triqs/gfs/imtime.hpp
@@ -46,8 +46,7 @@ namespace triqs { namespace gfs {
   template<typename Opt> struct singularity<imtime,scalar_valued,Opt>  { typedef local::tail type;};
   
   // h5 name
-  template<typename Opt> struct h5_name<imtime,matrix_valued,Opt>      { static std::string invoke(){ return  "GfImTime";}};
-  template<typename Opt> struct h5_name<imtime,scalar_valued,Opt>      { static std::string invoke(){ return  "GfImTime_s";}};
+  template<typename Opt> struct h5_name<imtime,matrix_valued,Opt>      { static std::string invoke(){ return  "ImTime";}};
 
   /// ---------------------------  data access  ---------------------------------
 
diff --git a/triqs/gfs/legendre.hpp b/triqs/gfs/legendre.hpp
index 04cc8597..c0e4c240 100644
--- a/triqs/gfs/legendre.hpp
+++ b/triqs/gfs/legendre.hpp
@@ -40,7 +40,7 @@ namespace triqs { namespace gfs {
   };
   
   // h5 name
-  template<typename Opt> struct h5_name<legendre,matrix_valued,Opt>      { static std::string invoke(){ return  "GfLegendre";}};
+  template<typename Opt> struct h5_name<legendre,matrix_valued,Opt>      { static std::string invoke(){ return  "Legendre";}};
 
   /// ---------------------------  evaluator ---------------------------------
 
diff --git a/triqs/gfs/re_im_time.hpp b/triqs/gfs/re_im_time.hpp
index 391f3393..834a0f2d 100644
--- a/triqs/gfs/re_im_time.hpp
+++ b/triqs/gfs/re_im_time.hpp
@@ -102,7 +102,7 @@ namespace triqs { namespace gfs {
   void assign_from_expression (gf_impl<Variable,Target,Opt,V> const &, RHS) {}
 
  //slices
- gf_view<retime,scalar_valued> slice_mesh_imtime (gf_view<re_im_time,scalar_valued> g, size_t index) { 
+ inline gf_view<retime,scalar_valued> slice_mesh_imtime (gf_view<re_im_time,scalar_valued> g, size_t index) { 
   auto arr = reinterpret_linear_array(g.mesh(),g.data()); // view it as a 2d array
   return { std::get<0>(g.mesh().components()), arr(arrays::range(), index), local::tail(1,1), nothing() };
  }
diff --git a/triqs/gfs/refreq.hpp b/triqs/gfs/refreq.hpp
index 7653fdc1..b94f47bd 100644
--- a/triqs/gfs/refreq.hpp
+++ b/triqs/gfs/refreq.hpp
@@ -45,8 +45,7 @@ namespace triqs { namespace gfs {
   template<typename Opt> struct singularity<refreq,scalar_valued,Opt>  { typedef local::tail type;};
   
   // h5 name
-  template<typename Opt> struct h5_name<refreq,matrix_valued,Opt>      { static std::string invoke(){ return "GfReFreq";}};
-  template<typename Opt> struct h5_name<refreq,scalar_valued,Opt>      { static std::string invoke(){ return "GfReFreq_s";}};
+  template<typename Opt> struct h5_name<refreq,matrix_valued,Opt>      { static std::string invoke(){ return "ReFreq";}};
 
   /// ---------------------------  evaluator ---------------------------------
   template<typename Opt, typename Target>
diff --git a/triqs/gfs/refreq_imtime.hpp b/triqs/gfs/refreq_imtime.hpp
index 07707723..ea7010d5 100644
--- a/triqs/gfs/refreq_imtime.hpp
+++ b/triqs/gfs/refreq_imtime.hpp
@@ -96,7 +96,7 @@ namespace triqs { namespace gfs {
   } // gfs_implementation
 
   //slices
- gf_view<refreq,scalar_valued> slice_mesh_imtime (gf_view<refreq_imtime,scalar_valued> g, size_t index) { 
+ inline gf_view<refreq,scalar_valued> slice_mesh_imtime (gf_view<refreq_imtime,scalar_valued> g, size_t index) { 
   auto arr = reinterpret_linear_array(g.mesh(),g.data()); // view it as a 2d array
   return { std::get<0>(g.mesh().components()), arr(arrays::range(),index), local::tail(1,1), nothing() };
  }
diff --git a/triqs/gfs/retime.hpp b/triqs/gfs/retime.hpp
index 11e2d7d5..dbddfa8f 100644
--- a/triqs/gfs/retime.hpp
+++ b/triqs/gfs/retime.hpp
@@ -47,8 +47,7 @@ namespace triqs { namespace gfs {
   template<typename Opt> struct singularity<retime,scalar_valued,Opt>  { typedef local::tail type;};
   
   // h5 name
-  template<typename Opt> struct h5_name<retime,matrix_valued,Opt>      { static std::string invoke(){ return  "GfReTime";}};
-  template<typename Opt> struct h5_name<retime,scalar_valued,Opt>      { static std::string invoke(){ return  "GfReTime_s";}};
+  template<typename Opt> struct h5_name<retime,matrix_valued,Opt>      { static std::string invoke(){ return  "ReTime";}};
 
   /// ---------------------------  evaluator ---------------------------------
   template<typename Opt, typename Target>