diff --git a/CMakeLists.txt b/CMakeLists.txt
index 2469fe96..3208e16b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -417,6 +417,10 @@ endif()
 #------------------------
 
 if (Build_Documentation)
+ if (NOT USE_CPP14) 
+  message(FATAL_ERROR " The documentation can only be compiled in C++14 mode")
+ endif()
+
  message( STATUS "-------- Prepare documentation -------------")
  add_subdirectory (${TRIQS_SOURCE_DIR}/doc )
  #add_dependencies(docs_sphinx py_sources)
diff --git a/test/triqs/gfs/CMakeLists.txt b/test/triqs/gfs/CMakeLists.txt
index 82067bf6..4423d27c 100644
--- a/test/triqs/gfs/CMakeLists.txt
+++ b/test/triqs/gfs/CMakeLists.txt
@@ -1,3 +1,3 @@
 link_libraries (triqs)
 all_tests()
-#add_subdirectory(multivar)
+add_subdirectory(multivar)
diff --git a/test/triqs/gfs/multivar/CMakeLists.txt b/test/triqs/gfs/multivar/CMakeLists.txt
new file mode 100644
index 00000000..0f046f98
--- /dev/null
+++ b/test/triqs/gfs/multivar/CMakeLists.txt
@@ -0,0 +1,5 @@
+link_libraries (triqs)
+
+if (USE_CPP14) 
+all_tests()
+endif()
diff --git a/test/triqs/gfs/curry1.cpp b/test/triqs/gfs/multivar/curry1.cpp
similarity index 100%
rename from test/triqs/gfs/curry1.cpp
rename to test/triqs/gfs/multivar/curry1.cpp
diff --git a/test/triqs/gfs/curry_and_fourier.cpp b/test/triqs/gfs/multivar/curry_and_fourier.cpp
similarity index 100%
rename from test/triqs/gfs/curry_and_fourier.cpp
rename to test/triqs/gfs/multivar/curry_and_fourier.cpp
diff --git a/test/triqs/gfs/g_k_om.cpp b/test/triqs/gfs/multivar/g_k_om.cpp
similarity index 100%
rename from test/triqs/gfs/g_k_om.cpp
rename to test/triqs/gfs/multivar/g_k_om.cpp
diff --git a/test/triqs/gfs/g_k_om2.cpp b/test/triqs/gfs/multivar/g_k_om2.cpp
similarity index 100%
rename from test/triqs/gfs/g_k_om2.cpp
rename to test/triqs/gfs/multivar/g_k_om2.cpp
diff --git a/test/triqs/gfs/g_k_tail.cpp b/test/triqs/gfs/multivar/g_k_tail.cpp
similarity index 100%
rename from test/triqs/gfs/g_k_tail.cpp
rename to test/triqs/gfs/multivar/g_k_tail.cpp
diff --git a/test/triqs/gfs/g_nu_nup.cpp b/test/triqs/gfs/multivar/g_nu_nup.cpp
similarity index 100%
rename from test/triqs/gfs/g_nu_nup.cpp
rename to test/triqs/gfs/multivar/g_nu_nup.cpp
diff --git a/test/triqs/gfs/g_om_nu_nup.cpp b/test/triqs/gfs/multivar/g_om_nu_nup.cpp
similarity index 100%
rename from test/triqs/gfs/g_om_nu_nup.cpp
rename to test/triqs/gfs/multivar/g_om_nu_nup.cpp
diff --git a/test/triqs/gfs/gf_2times.cpp b/test/triqs/gfs/multivar/gf_2times.cpp
similarity index 100%
rename from test/triqs/gfs/gf_2times.cpp
rename to test/triqs/gfs/multivar/gf_2times.cpp
diff --git a/test/triqs/gfs/vertex.cpp b/test/triqs/gfs/multivar/vertex.cpp
similarity index 100%
rename from test/triqs/gfs/vertex.cpp
rename to test/triqs/gfs/multivar/vertex.cpp
diff --git a/test/triqs/mpi/CMakeLists.txt b/test/triqs/mpi/CMakeLists.txt
index 917a5baf..22d7bd91 100644
--- a/test/triqs/mpi/CMakeLists.txt
+++ b/test/triqs/mpi/CMakeLists.txt
@@ -1,2 +1,3 @@
-all_tests()
-
+if (USE_CPP14)
+ all_tests()
+endif()
diff --git a/test/triqs/mpi/mpi_generic.cpp b/test/triqs/mpi/mpi_generic.cpp
index 1201f7d5..d3a93247 100644
--- a/test/triqs/mpi/mpi_generic.cpp
+++ b/test/triqs/mpi/mpi_generic.cpp
@@ -61,6 +61,7 @@ auto view_as_tuple(my_object &x) RETURN(std::tie(x.a, x.b));
 
 int main(int argc, char *argv[]) {
 
+#ifdef TRIQS_C11
  mpi::environment env(argc, argv);
  mpi::communicator world;
  
@@ -93,5 +94,6 @@ int main(int argc, char *argv[]) {
  out << " allgather b = " << ob.b << std::endl;
 
  out << "----------------------------"<< std::endl;
+#endif
 }
 
diff --git a/test/triqs/utility/tuple_tools.cpp b/test/triqs/utility/tuple_tools.cpp
index 41408e07..9c92e7a1 100644
--- a/test/triqs/utility/tuple_tools.cpp
+++ b/test/triqs/utility/tuple_tools.cpp
@@ -68,6 +68,7 @@ int main(int argc, char **argv) {
   if ( std::abs((res -  fun()(1,2.3,4.3,8))) > 1.e-13) throw std::runtime_error(" ");
  }
 
+#ifndef TRIQS_C11
  {
   auto r = triqs::tuple::map_on_zip_v2([](double x, double y) { return x + y; }, t1, t2);
   std::cerr  << " [f(a,b) for (a,b) in zip(t1,t2)] =" << r << std::endl; 
@@ -189,7 +190,7 @@ int main(int argc, char **argv) {
   std::cout << "replace 1,3,5"<< t << triqs::tuple::replace<1,3,5>(t,s)<< std::endl; 
  }
 
- 
+#endif
 
 
 }
diff --git a/triqs/gfs.hpp b/triqs/gfs.hpp
index 1d1ebdb6..9747b3c6 100644
--- a/triqs/gfs.hpp
+++ b/triqs/gfs.hpp
@@ -29,8 +29,12 @@
 #include <triqs/gfs/retime.hpp>
 #include <triqs/gfs/refreq.hpp>
 #include <triqs/gfs/legendre.hpp>
+
+// multivariable gf in C++14 only
+#ifndef TRIQS_C11
 #include <triqs/gfs/product.hpp>
 #include <triqs/gfs/curry.hpp>
+#endif
 
 #include <triqs/gfs/local/fourier_matsubara.hpp>
 #include <triqs/gfs/local/fourier_real.hpp>
diff --git a/triqs/gfs/gf.hpp b/triqs/gfs/gf.hpp
index e9004548..7dcd0d04 100644
--- a/triqs/gfs/gf.hpp
+++ b/triqs/gfs/gf.hpp
@@ -88,11 +88,6 @@ namespace gfs {
   // closest_point mechanism
   template <typename Variable, typename Target, typename Singularity, typename Opt> struct get_closest_point;
 
-  // singularity
-  //template <typename Variable, typename Target, typename Opt> struct singularity {
-  // using type = nothing;
-  //};
-
   // symmetry
   template <typename Variable, typename Target, typename Singularity, typename Opt> struct symmetry {
    using type = nothing;
@@ -426,6 +421,7 @@ namespace gfs {
   }
  }
 
+//#ifndef TRIQS_CPP11 
  template <typename RHS, typename Variable, typename Target, typename Singularity, typename Opt, bool IsView>
  void triqs_clef_auto_assign_impl(gf_impl<Variable, Target, Singularity, Opt, IsView, false> &g, RHS const &rhs,
                                   std::integral_constant<bool, true>) {
@@ -434,6 +430,7 @@ namespace gfs {
    //(*this)[w] = triqs::tuple::apply(rhs, w.components_tuple());
   }
  }
+//#endif
 
  // -------------------------The regular class of GF --------------------------------------------------------
 
diff --git a/triqs/gfs/meshes/product.c11.hpp b/triqs/gfs/meshes/product.c11.hpp
deleted file mode 100644
index 519dd8fe..00000000
--- a/triqs/gfs/meshes/product.c11.hpp
+++ /dev/null
@@ -1,269 +0,0 @@
-/*******************************************************************************
- *
- * TRIQS: a Toolbox for Research in Interacting Quantum Systems
- *
- * Copyright (C) 2012-2013 by O. Parcollet
- *
- * TRIQS is free software: you can redistribute it and/or modify it under the
- * terms of the GNU General Public License as published by the Free Software
- * Foundation, either version 3 of the License, or (at your option) any later
- * version.
- *
- * TRIQS is distributed in the hope that it will be useful, but WITHOUT ANY
- * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
- * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
- * details.
- *
- * You should have received a copy of the GNU General Public License along with
- * TRIQS. If not, see <http://www.gnu.org/licenses/>.
- *
- ******************************************************************************/
-#pragma once
-#include "./mesh_tools.hpp"
-#include "../domains/product.hpp"
-#include <triqs/utility/tuple_tools.hpp>
-#include <triqs/utility/mini_vector.hpp>
-#include <triqs/utility/c14.hpp>
-namespace triqs {
-namespace gfs {
-
- /** Cartesian product of meshes
-  */
- template <typename... Meshes> struct mesh_product : tag::composite {
-  using domain_t = domain_product<typename Meshes::domain_t...>;
-  using index_t = std::c14::tuple<typename Meshes::index_t...>;
-  using m_tuple_t = std::tuple<Meshes...>;
-  using m_pt_tuple_t = std::tuple<typename Meshes::mesh_point_t...>;
-  using domain_pt_t = typename domain_t::point_t;
-
-  static constexpr int dim = sizeof...(Meshes);
-
-  mesh_product() {}
-  mesh_product(Meshes const &... meshes) : m_tuple(meshes...), _dom(meshes.domain()...) {}
-
-  domain_t const &domain() const { return _dom; }
-  m_tuple_t const &components() const { return m_tuple; }
-  m_tuple_t &components() { return m_tuple; }
-
-  private:
-  struct _aux0 {
-   template <typename M> size_t operator()(M const &m, size_t R) { return R * m.size(); }
-  };
-
-  public:
-  /// size of the mesh is the product of size
-  size_t size() const { return triqs::tuple::fold(_aux0(), m_tuple, 1); }
-
-  private:
-  struct _aux1 {
-   template <typename P, typename M, typename I> void operator()(P &p, M const &m, I const &i) { p = m.index_to_point(i); }
-  };
-
-  public:
-  /// Conversions point <-> index <-> linear_index
-  typename domain_t::point_t index_to_point(index_t const &ind) const {
-   domain_pt_t res;
-   triqs::tuple::map_on_zip(_aux1(), res, m_tuple, ind);
-   return res;
-  }
-
-  private:
-  struct _aux2 {
-   template <typename I, typename M> size_t operator()(M const &m, I const &i, size_t R) {
-    return m.index_to_linear(i) + R * m.size();
-   }
-  };
-
-  public:
-  /// Flattening index to linear :  index[0] + component[0].size * (index[1] + component[1].size* (index[2] + ....))
-  size_t index_to_linear(index_t const &ii) const {
-   return triqs::tuple::fold(_aux2(), reverse(m_tuple), reverse(ii), size_t(0));
-  }
-
-  private:
-  struct _aux3 {
-   template <typename P, typename M> size_t operator()(M const &m, P const &p, size_t R) {
-    return p.linear_index() + R * m.size();
-   }
-  };
-
-  public:
-  /// Flattening index to linear :  index[0] + component[0].size * (index[1] + component[1].size* (index[2] + ....))
-  size_t mp_to_linear(m_pt_tuple_t const &mp) const {
-   return triqs::tuple::fold(_aux3(), reverse(m_tuple), reverse(mp), size_t(0));
-  }
-
-  //
-  private:
-  struct _aux4 {
-   template <typename M, typename V> V *operator()(M const &m, V *v) {
-    *v = m.size();
-    return ++v;
-   }
-  };
-
-  public:
-  utility::mini_vector<size_t, dim> shape() const {
-   utility::mini_vector<size_t, dim> res;
-   triqs::tuple::fold(_aux4(), m_tuple, &res[0]);
-   return res;
-  }
-
-  // Same but a variadic list of mesh_point_t
-  template <typename... MP> size_t mesh_pt_components_to_linear(MP const &... mp) const {
-   static_assert(std::is_same<std::tuple<MP...>, m_pt_tuple_t>::value, "Call incorrect ");
-   // static_assert(std::is_same< std::tuple<typename std::remove_cv<typename std::remove_reference<MP>::type>::type...>,
-   // m_pt_tuple_t>::value, "Call incorrect ");
-   return mp_to_linear(std::forward_as_tuple(mp...));
-  } // speed test ? or make a variadic fold...
-
-  /// The wrapper for the mesh point
-  class mesh_point_t : tag::mesh_point {
-   const mesh_product *m;
-   m_pt_tuple_t _c;
-   bool _atend;
-   struct F2 {
-    template <typename M> typename M::mesh_point_t operator()(M const &m, typename M::index_t const &i) const { return m[i]; }
-   };
-   struct F1 {
-    template <typename M> typename M::mesh_point_t operator()(M const &m) const { return {m}; }
-   };
-
-   public:
-   mesh_point_t() = default;
-   mesh_point_t(mesh_product const &m_, index_t index_)
-      : m(&m_), _c(triqs::tuple::map_on_zip(F2(), m_.m_tuple, index_)), _atend(false) {}
-   mesh_point_t(mesh_product const &m_) : m(&m_), _c(triqs::tuple::map(F1(), m_.m_tuple)), _atend(false) {}
-   m_pt_tuple_t const &components_tuple() const { return _c; }
-   size_t linear_index() const { return m->mp_to_linear(_c); }
-   const mesh_product *mesh() const { return m; }
-
-   using cast_t = domain_pt_t;
-   operator cast_t() const { return m->index_to_point(index); }
-
-   // index[0] +=1; if index[0]==m.component[0].size() { index[0]=0; index[1] +=1; if  ....}  and so on until dim
-   private:
-   struct _aux1 {
-    template <typename P> bool operator()(P &p, bool done) {
-     if (done) return true;
-     p.advance();
-     if (!p.at_end()) return true;
-     p.reset();
-     return false;
-    }
-   };
-
-   public:
-   void advance() { _atend = ! (triqs::tuple::fold(_aux1(), _c, false)) ; }
-
-   // index_t index() const { return _index;} // not implemented yet
-   bool at_end() const { return _atend; }
-
-   private:
-   struct _aux {
-    template <typename M> size_t operator()(M &m, size_t) {
-     m.reset();
-     return 0;
-    }
-   };
-
-   public:
-   void reset() {
-    _atend = false;
-    triqs::tuple::fold(_aux(), _c, 0);
-   }
-  }; // end mesh_point_t
-
-  /// Accessing a point of the mesh
-  mesh_point_t operator[](index_t i) const { return mesh_point_t(*this, i); }
-  mesh_point_t operator()(typename Meshes::index_t... i) const { return (*this)[std::make_tuple(i...)]; }
-
-  /// Iterating on all the points...
-  using const_iterator = mesh_pt_generator<mesh_product>;
-  const_iterator begin() const { return const_iterator(this); }
-  const_iterator end() const { return const_iterator(this, true); }
-  const_iterator cbegin() const { return const_iterator(this); }
-  const_iterator cend() const { return const_iterator(this, true); }
-
-  /// Mesh comparison
-  friend bool operator==(mesh_product const &M1, mesh_product const &M2) { return M1.m_tuple == M2.m_tuple; }
-  
-  private:
-
-  /// Write into HDF5
-  struct _auxh5w {
-   h5::group gr;
-   _auxh5w(h5::group gr_) : gr(gr_) {} // icc has yet another bug on new initialization form with {}...
-   template <typename M> size_t operator()(M const &m, size_t N) {
-    std::stringstream fs;
-    fs << "MeshComponent" << N;
-    h5_write(gr, fs.str(), m);
-    return N + 1;
-   }
-  };
-
-  friend void h5_write(h5::group fg, std::string subgroup_name, mesh_product const &m) {
-   h5::group gr = fg.create_group(subgroup_name);
-   // h5_write(gr,"domain",m.domain());
-   triqs::tuple::fold(_auxh5w(gr), m.components(), size_t(0));
-  }
-
-  /// Read from HDF5
-  struct _auxh5r {
-   h5::group gr;
-   _auxh5r(h5::group gr_) : gr(gr_) {}
-   template <typename M> size_t operator()(M &m, size_t N) {
-    std::stringstream fs;
-    fs << "MeshComponent" << N;
-    h5_read(gr, fs.str(), m);
-    return N + 1;
-   }
-  };
-  friend void h5_read(h5::group fg, std::string subgroup_name, mesh_product &m) {
-   h5::group gr = fg.open_group(subgroup_name);
-   // h5_read(gr,"domain",m._dom);
-   triqs::tuple::fold(_auxh5r(gr), m.components(), size_t(0));
-  }
-
-  //  BOOST Serialization
-  friend class boost::serialization::access;
-  template <typename Archive> struct _aux_ser {
-   Archive &ar;
-   _aux_ser(Archive &ar_) : ar(ar_) {}
-   template <typename M> size_t operator()(M &m, size_t N) {
-    std::stringstream fs;
-    fs << "MeshComponent" << N;
-    ar &TRIQS_MAKE_NVP(fs.str().c_str(), m);
-    return N + 1;
-   }
-  };
-  template <class Archive> void serialize(Archive &ar, const unsigned int version) {
-   triqs::tuple::fold(_aux_ser<Archive>(ar), m_tuple, size_t(0));
-  }
-
-  friend std::ostream &operator<<(std::ostream &sout, mesh_product const &m) { return sout << "Product Mesh"; }
-
-  private:
-  m_tuple_t m_tuple;
-  domain_t _dom;
- };
-
- template <int pos, typename P> auto get_index(P const &p) DECL_AND_RETURN(std::get<pos>(p.components_tuple()).index());
-
- template <int pos, typename P>
- auto get_point(P const &p)
-     DECL_AND_RETURN(std::get<pos>(p.mesh() -> components()).index_to_point(std::get<pos>(p.components_tuple()).index()));
-
- template <int pos, typename P> auto get_component(P const &p) DECL_AND_RETURN(std::get<pos>(p.components_tuple()));
-
- // Given a composite mesh m , and a linear array of storage A
- // reinterpret_linear_array(m,A) returns a d-dimensionnal view of the array
- // with indices egal to the indices of the components of the mesh.
- // Very useful for slicing, currying functions.
- template <typename... Meshes, typename T, ull_t OptionsFlags, ull_t To, int R, bool B, bool C>
- arrays::array_view<T, sizeof...(Meshes) + R - 1, OptionsFlags, To, true, C>
- reinterpret_linear_array(mesh_product<Meshes...> const &m, arrays::array_view<T, R, OptionsFlags, To, B, C> A) {
-  return {{join(m.shape(), get_shape(A).front_pop())}, A.storage()};
- }
-}
-}
diff --git a/triqs/gfs/meshes/product.c14.hpp b/triqs/gfs/meshes/product.c14.hpp
deleted file mode 100644
index dd0f3e28..00000000
--- a/triqs/gfs/meshes/product.c14.hpp
+++ /dev/null
@@ -1,197 +0,0 @@
-/*******************************************************************************
- *
- * TRIQS: a Toolbox for Research in Interacting Quantum Systems
- *
- * Copyright (C) 2012-2014 by O. Parcollet
- *
- * TRIQS is free software: you can redistribute it and/or modify it under the
- * terms of the GNU General Public License as published by the Free Software
- * Foundation, either version 3 of the License, or (at your option) any later
- * version.
- *
- * TRIQS is distributed in the hope that it will be useful, but WITHOUT ANY
- * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
- * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
- * details.
- *
- * You should have received a copy of the GNU General Public License along with
- * TRIQS. If not, see <http://www.gnu.org/licenses/>.
- *
- ******************************************************************************/
-#pragma once
-#include "./mesh_tools.hpp"
-#include "../domains/product.hpp"
-#include <triqs/utility/tuple_tools.hpp>
-#include <triqs/utility/mini_vector.hpp>
-#include <triqs/utility/c14.hpp>
-namespace triqs {
-namespace gfs {
-
- /** Cartesian product of meshes */
- template <typename... Meshes> struct mesh_product : tag::composite {
-  using domain_t = domain_product<typename Meshes::domain_t...>;
-  using index_t = std::c14::tuple<typename Meshes::index_t...>;
-  using m_tuple_t = std::tuple<Meshes...>;
-  using m_pt_tuple_t = std::tuple<typename Meshes::mesh_point_t...>;
-  using domain_pt_t = typename domain_t::point_t;
-  using linear_index_t = std::tuple<typename Meshes::linear_index_t...>;
-
-  static constexpr int dim = sizeof...(Meshes);
-
-  mesh_product() {}
-  mesh_product(Meshes const &... meshes) : m_tuple(meshes...), _dom(meshes.domain()...) {}
-  mesh_product(mesh_product const &) = default;
-
-  domain_t const &domain() const { return _dom; }
-  m_tuple_t const &components() const { return m_tuple; }
-  m_tuple_t &components() { return m_tuple; }
-
-  /// size of the mesh is the product of size
-  size_t size() const {
-   return triqs::tuple::fold([](auto const &m, size_t R) { return R * m.size(); }, m_tuple, 1);
-  }
-/*
-  /// Scatter the first mesh over the communicator c
-  friend mesh_product mpi_scatter(mesh_product const &m, mpi::communicator c, int root) {
-   auto r = m; // same domain, but mesh with a window. Ok ?
-   std::get<0>(r.m_tuple) = mpi_scatter(std::get<0>(r.m_tuple), c, root);
-   return r;
-  }
-
-  /// Opposite of scatter : rebuild the original mesh, without a window
-  friend mesh_product mpi_gather(mesh_product m, mpi::communicator c, int root) {
-   auto r = m; // same domain, but mesh with a window. Ok ?
-   std::get<0>(r.m_tuple) = mpi_gather(std::get<0>(r.m_tuple), c, root);
-   return r;
-  */
-
-   /// The sizes of all mesh components
-  utility::mini_vector<size_t, dim> size_of_components() const {
-   utility::mini_vector<size_t, dim> res;
-   auto l = [&res](int i, auto const &m) mutable { res[i] = m.size(); };
-   triqs::tuple::for_each_enumerate(m_tuple, l);
-   return res;
-  }
-
-  /// Conversions point <-> index <-> linear_index
-  typename domain_t::point_t index_to_point(index_t const &ind) const {
-   domain_pt_t res;
-   auto l = [](auto &p, auto const &m, auto const &i) { p = m.index_to_point(i); };
-   triqs::tuple::map_on_zip(l, res, m_tuple, ind);
-   return res;
-  }
-
-  /// The linear_index is the tuple of the linear_index of the components
-  linear_index_t index_to_linear(index_t const &ind) const {
-   auto l = [](auto const &m, auto const &i) { return m.index_to_linear(i); };
-   return triqs::tuple::map_on_zip(l, m_tuple, ind);
-  }
-  
-  /// 
-  linear_index_t mp_to_linear(m_pt_tuple_t const &mp) const {
-   auto l = [](auto const &p) { return p.linear_index(); };
-   return triqs::tuple::map(l, mp);
-  }
-
-  // Same but a variadic list of mesh_point_t
-  template <typename... MP> size_t mesh_pt_components_to_linear(MP const &... mp) const {
-   static_assert(std::is_same<std::tuple<MP...>, m_pt_tuple_t>::value, "Call incorrect ");
-   return mp_to_linear(std::forward_as_tuple(mp...));
-  } 
-
-  /// The wrapper for the mesh point
-  class mesh_point_t : tag::mesh_point {
-   const mesh_product *m;
-   m_pt_tuple_t _c;
-   bool _atend;
-   struct F1 {
-    template <typename M> typename M::mesh_point_t operator()(M const &m) const { return {m}; }
-   };
-
-   public:
-   mesh_point_t() = default;
-   mesh_point_t(mesh_product const &m_, index_t index_)
-      : m(&m_)
-      , _c(triqs::tuple::map_on_zip([](auto const & m, auto const & i) { return m[i]; }, m_.m_tuple, index_))
-      , _atend(false) {}
-   mesh_point_t(mesh_product const &m_) : m(&m_), _c(triqs::tuple::map(F1(), m_.m_tuple)), _atend(false) {}
-   m_pt_tuple_t const &components_tuple() const { return _c; }
-   linear_index_t linear_index() const { return m->mp_to_linear(_c); }
-   const mesh_product *mesh() const { return m; }
-
-   using cast_t = domain_pt_t;
-   operator cast_t() const { return m->index_to_point(index); }
-
-   // index[0] +=1; if index[0]==m.component[0].size() { index[0]=0; index[1] +=1; if  ....}  and so on until dim
-   void advance() {
-    auto l = [](auto &p, bool done) {
-     if (done) return true;
-     p.advance();
-     if (!p.at_end()) return true;
-     p.reset();
-     return false;
-    };
-    _atend = !(triqs::tuple::fold(l, _c, false));
-   }
-
-   // index_t index() const { return _index;} // not implemented yet
-   bool at_end() const { return _atend; }
-
-   void reset() {
-    _atend = false;
-    triqs::tuple::for_each(_c, [](auto &m) { m.reset(); });
-   }
-  }; // end mesh_point_t
-
-  /// Accessing a point of the mesh
-  mesh_point_t operator[](index_t i) const { return mesh_point_t(*this, i); }
-  mesh_point_t operator()(typename Meshes::index_t... i) const { return (*this)[std::make_tuple(i...)]; }
-
-  /// Iterating on all the points...
-  using const_iterator = mesh_pt_generator<mesh_product>;
-  const_iterator begin() const { return const_iterator(this); }
-  const_iterator end() const { return const_iterator(this, true); }
-  const_iterator cbegin() const { return const_iterator(this); }
-  const_iterator cend() const { return const_iterator(this, true); }
-
-  /// Mesh comparison
-  friend bool operator==(mesh_product const &M1, mesh_product const &M2) { return M1.m_tuple == M2.m_tuple; }
-
-  /// Write into HDF5
-  friend void h5_write(h5::group fg, std::string subgroup_name, mesh_product const &m) {
-   h5::group gr = fg.create_group(subgroup_name);
-   auto l = [gr](int N, auto const &m) { h5_write(gr, "MeshComponent" + std::to_string(N), m); };
-   triqs::tuple::for_each_enumerate(m.components(), l);
-  }
-
-  /// Read from HDF5
-  friend void h5_read(h5::group fg, std::string subgroup_name, mesh_product &m) {
-   h5::group gr = fg.open_group(subgroup_name);
-   auto l = [gr](int N, auto &m) { h5_read(gr, "MeshComponent" + std::to_string(N), m); };
-   triqs::tuple::for_each_enumerate(m.components(), l);
-  }
-
-  /// BOOST Serialization
-  friend class boost::serialization::access;
-  template <class Archive> void serialize(Archive &ar, const unsigned int version) {
-   auto l = [&ar](int N, auto &m) { ar &TRIQS_MAKE_NVP("MeshComponent" + std::to_string(N), m); };
-   triqs::tuple::for_each_enumerate(m_tuple, l);
-  }
-
-  friend std::ostream &operator<<(std::ostream &sout, mesh_product const &m) { return sout << "Product Mesh"; }
-
-  private:
-  m_tuple_t m_tuple;
-  domain_t _dom;
- };
-
- template <int pos, typename P> decltype(auto) get_index(P const &p) {return std::get<pos>(p.components_tuple()).index();}
-
- template <int pos, typename P> decltype(auto) get_point(P const &p) {
-  return std::get<pos>(p.mesh()->components()).index_to_point(std::get<pos>(p.components_tuple()).index());
- }
-
- template <int pos, typename P> decltype(auto) get_component(P const &p) { return std::get<pos>(p.components_tuple()); }
-
-}
-}
diff --git a/triqs/gfs/meshes/product.hpp b/triqs/gfs/meshes/product.hpp
index 6af90566..dd0f3e28 100644
--- a/triqs/gfs/meshes/product.hpp
+++ b/triqs/gfs/meshes/product.hpp
@@ -2,7 +2,7 @@
  *
  * TRIQS: a Toolbox for Research in Interacting Quantum Systems
  *
- * Copyright (C) 2012-2013 by O. Parcollet
+ * Copyright (C) 2012-2014 by O. Parcollet
  *
  * TRIQS is free software: you can redistribute it and/or modify it under the
  * terms of the GNU General Public License as published by the Free Software
@@ -19,11 +19,179 @@
  *
  ******************************************************************************/
 #pragma once
-#if defined(__cpp_generic_lambdas) && defined (__cpp_decltype_auto) && defined(__cpp_return_type_deduction)
-// simplest code, in c++14
-#include "./product.c14.hpp"
-#else
-// workaround for C++11
-#include "./product.c11.hpp"
-#endif
+#include "./mesh_tools.hpp"
+#include "../domains/product.hpp"
+#include <triqs/utility/tuple_tools.hpp>
+#include <triqs/utility/mini_vector.hpp>
+#include <triqs/utility/c14.hpp>
+namespace triqs {
+namespace gfs {
 
+ /** Cartesian product of meshes */
+ template <typename... Meshes> struct mesh_product : tag::composite {
+  using domain_t = domain_product<typename Meshes::domain_t...>;
+  using index_t = std::c14::tuple<typename Meshes::index_t...>;
+  using m_tuple_t = std::tuple<Meshes...>;
+  using m_pt_tuple_t = std::tuple<typename Meshes::mesh_point_t...>;
+  using domain_pt_t = typename domain_t::point_t;
+  using linear_index_t = std::tuple<typename Meshes::linear_index_t...>;
+
+  static constexpr int dim = sizeof...(Meshes);
+
+  mesh_product() {}
+  mesh_product(Meshes const &... meshes) : m_tuple(meshes...), _dom(meshes.domain()...) {}
+  mesh_product(mesh_product const &) = default;
+
+  domain_t const &domain() const { return _dom; }
+  m_tuple_t const &components() const { return m_tuple; }
+  m_tuple_t &components() { return m_tuple; }
+
+  /// size of the mesh is the product of size
+  size_t size() const {
+   return triqs::tuple::fold([](auto const &m, size_t R) { return R * m.size(); }, m_tuple, 1);
+  }
+/*
+  /// Scatter the first mesh over the communicator c
+  friend mesh_product mpi_scatter(mesh_product const &m, mpi::communicator c, int root) {
+   auto r = m; // same domain, but mesh with a window. Ok ?
+   std::get<0>(r.m_tuple) = mpi_scatter(std::get<0>(r.m_tuple), c, root);
+   return r;
+  }
+
+  /// Opposite of scatter : rebuild the original mesh, without a window
+  friend mesh_product mpi_gather(mesh_product m, mpi::communicator c, int root) {
+   auto r = m; // same domain, but mesh with a window. Ok ?
+   std::get<0>(r.m_tuple) = mpi_gather(std::get<0>(r.m_tuple), c, root);
+   return r;
+  */
+
+   /// The sizes of all mesh components
+  utility::mini_vector<size_t, dim> size_of_components() const {
+   utility::mini_vector<size_t, dim> res;
+   auto l = [&res](int i, auto const &m) mutable { res[i] = m.size(); };
+   triqs::tuple::for_each_enumerate(m_tuple, l);
+   return res;
+  }
+
+  /// Conversions point <-> index <-> linear_index
+  typename domain_t::point_t index_to_point(index_t const &ind) const {
+   domain_pt_t res;
+   auto l = [](auto &p, auto const &m, auto const &i) { p = m.index_to_point(i); };
+   triqs::tuple::map_on_zip(l, res, m_tuple, ind);
+   return res;
+  }
+
+  /// The linear_index is the tuple of the linear_index of the components
+  linear_index_t index_to_linear(index_t const &ind) const {
+   auto l = [](auto const &m, auto const &i) { return m.index_to_linear(i); };
+   return triqs::tuple::map_on_zip(l, m_tuple, ind);
+  }
+  
+  /// 
+  linear_index_t mp_to_linear(m_pt_tuple_t const &mp) const {
+   auto l = [](auto const &p) { return p.linear_index(); };
+   return triqs::tuple::map(l, mp);
+  }
+
+  // Same but a variadic list of mesh_point_t
+  template <typename... MP> size_t mesh_pt_components_to_linear(MP const &... mp) const {
+   static_assert(std::is_same<std::tuple<MP...>, m_pt_tuple_t>::value, "Call incorrect ");
+   return mp_to_linear(std::forward_as_tuple(mp...));
+  } 
+
+  /// The wrapper for the mesh point
+  class mesh_point_t : tag::mesh_point {
+   const mesh_product *m;
+   m_pt_tuple_t _c;
+   bool _atend;
+   struct F1 {
+    template <typename M> typename M::mesh_point_t operator()(M const &m) const { return {m}; }
+   };
+
+   public:
+   mesh_point_t() = default;
+   mesh_point_t(mesh_product const &m_, index_t index_)
+      : m(&m_)
+      , _c(triqs::tuple::map_on_zip([](auto const & m, auto const & i) { return m[i]; }, m_.m_tuple, index_))
+      , _atend(false) {}
+   mesh_point_t(mesh_product const &m_) : m(&m_), _c(triqs::tuple::map(F1(), m_.m_tuple)), _atend(false) {}
+   m_pt_tuple_t const &components_tuple() const { return _c; }
+   linear_index_t linear_index() const { return m->mp_to_linear(_c); }
+   const mesh_product *mesh() const { return m; }
+
+   using cast_t = domain_pt_t;
+   operator cast_t() const { return m->index_to_point(index); }
+
+   // index[0] +=1; if index[0]==m.component[0].size() { index[0]=0; index[1] +=1; if  ....}  and so on until dim
+   void advance() {
+    auto l = [](auto &p, bool done) {
+     if (done) return true;
+     p.advance();
+     if (!p.at_end()) return true;
+     p.reset();
+     return false;
+    };
+    _atend = !(triqs::tuple::fold(l, _c, false));
+   }
+
+   // index_t index() const { return _index;} // not implemented yet
+   bool at_end() const { return _atend; }
+
+   void reset() {
+    _atend = false;
+    triqs::tuple::for_each(_c, [](auto &m) { m.reset(); });
+   }
+  }; // end mesh_point_t
+
+  /// Accessing a point of the mesh
+  mesh_point_t operator[](index_t i) const { return mesh_point_t(*this, i); }
+  mesh_point_t operator()(typename Meshes::index_t... i) const { return (*this)[std::make_tuple(i...)]; }
+
+  /// Iterating on all the points...
+  using const_iterator = mesh_pt_generator<mesh_product>;
+  const_iterator begin() const { return const_iterator(this); }
+  const_iterator end() const { return const_iterator(this, true); }
+  const_iterator cbegin() const { return const_iterator(this); }
+  const_iterator cend() const { return const_iterator(this, true); }
+
+  /// Mesh comparison
+  friend bool operator==(mesh_product const &M1, mesh_product const &M2) { return M1.m_tuple == M2.m_tuple; }
+
+  /// Write into HDF5
+  friend void h5_write(h5::group fg, std::string subgroup_name, mesh_product const &m) {
+   h5::group gr = fg.create_group(subgroup_name);
+   auto l = [gr](int N, auto const &m) { h5_write(gr, "MeshComponent" + std::to_string(N), m); };
+   triqs::tuple::for_each_enumerate(m.components(), l);
+  }
+
+  /// Read from HDF5
+  friend void h5_read(h5::group fg, std::string subgroup_name, mesh_product &m) {
+   h5::group gr = fg.open_group(subgroup_name);
+   auto l = [gr](int N, auto &m) { h5_read(gr, "MeshComponent" + std::to_string(N), m); };
+   triqs::tuple::for_each_enumerate(m.components(), l);
+  }
+
+  /// BOOST Serialization
+  friend class boost::serialization::access;
+  template <class Archive> void serialize(Archive &ar, const unsigned int version) {
+   auto l = [&ar](int N, auto &m) { ar &TRIQS_MAKE_NVP("MeshComponent" + std::to_string(N), m); };
+   triqs::tuple::for_each_enumerate(m_tuple, l);
+  }
+
+  friend std::ostream &operator<<(std::ostream &sout, mesh_product const &m) { return sout << "Product Mesh"; }
+
+  private:
+  m_tuple_t m_tuple;
+  domain_t _dom;
+ };
+
+ template <int pos, typename P> decltype(auto) get_index(P const &p) {return std::get<pos>(p.components_tuple()).index();}
+
+ template <int pos, typename P> decltype(auto) get_point(P const &p) {
+  return std::get<pos>(p.mesh()->components()).index_to_point(std::get<pos>(p.components_tuple()).index());
+ }
+
+ template <int pos, typename P> decltype(auto) get_component(P const &p) { return std::get<pos>(p.components_tuple()); }
+
+}
+}
diff --git a/triqs/mpi.hpp b/triqs/mpi.hpp
index 43625d92..1714224b 100644
--- a/triqs/mpi.hpp
+++ b/triqs/mpi.hpp
@@ -18,12 +18,13 @@
  * TRIQS. If not, see <http://www.gnu.org/licenses/>.
  *
  ******************************************************************************/
-#ifndef TRIQS_MPI_H
-#define TRIQS_MPI_H
+#pragma once
 
 #include "./mpi/arrays.hpp"
 #include "./mpi/vector.hpp"
-#include "./mpi/generic.hpp"
 
+#ifndef TRIQS_C11
+#include "./mpi/generic.hpp"
 #endif
 
+
diff --git a/triqs/mpi/generic.hpp b/triqs/mpi/generic.hpp
index c64764a6..c537018a 100644
--- a/triqs/mpi/generic.hpp
+++ b/triqs/mpi/generic.hpp
@@ -48,7 +48,6 @@ namespace mpi {
    return invoke_impl(std::integral_constant<bool, with_lazy>(), Tag(), c, a, root);
   }
 
-#ifdef __cpp_generic_lambdas
   static void reduce_in_place(communicator c, T &a, int root) {
    tuple::for_each(view_as_tuple(a), [c, root](auto &x) { triqs::mpi::reduce_in_place(x, c, root); });
   }
@@ -62,45 +61,6 @@ namespace mpi {
    triqs::tuple::for_each_zip(l, view_as_tuple(target), view_as_tuple(laz.ref));
    return target;
   }
-
-#else
-
-  struct aux1 {
-   communicator c;
-   int root;
-
-   template <typename T1> void operator()(T1 &x) const { triqs::mpi::reduce_in_place(c, x, root); }
-  };
-
-  static void reduce_in_place(communicator c, T &a, int root) {
-   tuple::for_each(aux1{c, root}, view_as_tuple(a));
-  }
-
-  struct aux2 {
-   communicator c;
-   int root;
-
-   template <typename T2> void operator()(T2 &x) const { triqs::mpi::broadcast(c, x, root); }
-  };
-
-  static void broadcast(communicator c, T &a, int root) {
-   tuple::for_each(aux2{c, root}, view_as_tuple(a));
-  }
-
-  template <typename Tag> struct aux3 {
-   mpi_lazy<Tag, T> laz;
-
-   template <typename T1, typename T2> void operator()(T1 &t, T2 &s) const {
-    t = triqs::mpi::mpi_impl<T2>::invoke(Tag(), laz.c, laz.s);
-   }
-  };
-
-  template <typename Tag> static T& complete_operation(T &target, mpi_lazy<Tag, T> laz) {
-   auto l = aux3<Tag>{laz};
-   triqs::tuple::for_each_zip(l, view_as_tuple(target), view_as_tuple(laz.ref));
-   return target;
-  }
-#endif
  };
 
  // If type T has a mpi_implementation nested struct, then it is mpi_impl<T>.
diff --git a/triqs/mpi/gf.hpp b/triqs/mpi/gf.hpp
index f11a8c1e..a2c1d949 100644
--- a/triqs/mpi/gf.hpp
+++ b/triqs/mpi/gf.hpp
@@ -20,7 +20,6 @@
  ******************************************************************************/
 #pragma once
 #include "./base.hpp"
-#include <triqs/mpi/generic.hpp>
 
 namespace triqs {
 namespace mpi {
diff --git a/triqs/operators/serialization.hpp b/triqs/operators/serialization.hpp
new file mode 100644
index 00000000..4930dc53
--- /dev/null
+++ b/triqs/operators/serialization.hpp
@@ -0,0 +1,27 @@
+/*******************************************************************************
+ *
+ * TRIQS: a Toolbox for Research in Interacting Quantum Systems
+ *
+ * Copyright (C) 2014 by I. Krivenko, O. Parcollet, M. Ferrero
+ *
+ * TRIQS is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later
+ * version.
+ *
+ * TRIQS is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * TRIQS. If not, see <http://www.gnu.org/licenses/>.
+ *
+ ******************************************************************************/
+#pragma once
+#include <triqs/operators/many_body_operator.hpp>
+#include <boost/serialization/vector.hpp>
+#include <boost/serialization/map.hpp>
+#include <boost/serialization/variant.hpp>
+
+
diff --git a/triqs/utility/tuple_tools.hpp b/triqs/utility/tuple_tools.hpp
index 9d20401f..ac9fe71f 100644
--- a/triqs/utility/tuple_tools.hpp
+++ b/triqs/utility/tuple_tools.hpp
@@ -68,6 +68,7 @@ namespace std {
 
 namespace triqs { namespace tuple {
 
+ /*
  /// Repeat an element
  template<typename T, int R> struct make_tuple_repeat_impl;
  
@@ -86,6 +87,7 @@ namespace triqs { namespace tuple {
  };
 
  template <int R, typename T> auto make_tuple_repeat(T &&x) { return make_tuple_repeat_impl<T, R>::invoke(std::forward<T>(x)); }
+*/
 
  /// _get_seq<T>() : from a tuple T, return the index sequence of the tuple length
  template <typename T> std14::make_index_sequence<std::tuple_size<std14::decay_t<T>>::value> _get_seq() {
@@ -286,13 +288,16 @@ namespace triqs { namespace tuple {
  auto map_on_zip(F &&f, T0 &&t0, T1 &&t1, T2 &&t2)
      RETURN(_map_impl(std::forward<F>(f), std::forward<T0>(t0), std::forward<T1>(t1), std::forward<T2>(t2), _get_seq<T0>()));
 
+#ifdef TRIQS_C11
+}}
+#else
+
 /**
  * fold(f, t1, r_init)
  * f : a callable object : f(x,r) -> r'
  * t a tuple
  * Returns : f(xN,f(x_N-1,...f(x0,r_init)) on the tuple
  */
-#ifndef TRIQS_C11
  template <int pos, typename F, typename T, typename R> decltype(auto) fold_impl(_int<pos>, F &&f, T &&t, R &&r) {
   return fold_impl(_int<pos - 1>(), std::forward<F>(f), std::forward<T>(t),
                    f(std::get<_get_seq_len<T>() - 1 - pos>(t), std::forward<R>(r)));
@@ -302,26 +307,6 @@ namespace triqs { namespace tuple {
  template <typename F, typename T, typename R> decltype(auto) fold(F &&f, T &&t, R &&r) {
   return fold_impl(_int<_get_seq_len<T>() - 1>(), std::forward<F>(f), std::forward<T>(t), std::forward<R>(r));
  }
-#else
- // old implementation, not modified for C++11
-
- template <int N, int pos, typename T> struct fold_impl {
-  template <typename F, typename R>
-  auto operator()(F &&f, T &&t,
-                  R &&r)DECL_AND_RETURN(fold_impl<N, pos - 1, T>()(std::forward<F>(f), std::forward<T>(t),
-                                                                   f(std::get<N - 1 - pos>(t), std::forward<R>(r))));
- };
-
- template <int N, typename T> struct fold_impl<N, -1, T> {
-  template <typename F, typename R> R operator()(F &&f, T &&t, R &&r) { return std::forward<R>(r); }
- };
-
- template <typename F, typename T, typename R>
- auto fold(F &&f, T &&t, R &&r)
-     DECL_AND_RETURN(fold_impl<std::tuple_size<std::c14::decay_t<T>>::value, std::tuple_size<std::c14::decay_t<T>>::value - 1,
-                               T>()(std::forward<F>(f), std::forward<T>(t), std::forward<R>(r)));
-
-#endif
 
  /**
   * fold(f, r_init, t1, t2)
@@ -330,7 +315,6 @@ namespace triqs { namespace tuple {
   * Returns : f(x0,y0,f(x1,y1,,f(....)) for t1 = (x0,x1 ...) and t2 = (y0,y1...).
   */
 
-#ifndef TRIQS_C11
  template <int pos, typename F, typename T0, typename T1, typename R>
  decltype(auto) fold_impl(_int<pos>, F &&f, T0 &&t0, T1 &&t1, R &&r) {
   constexpr int n = _get_seq_len<T0>() - 1 - pos;
@@ -346,24 +330,6 @@ namespace triqs { namespace tuple {
   return fold_impl(_int<_get_seq_len<T0>() - 1>(), std::forward<F>(f), std::forward<T0>(t0), std::forward<T1>(t1),
                    std::forward<R>(r));
  }
-#else
-// old implementation, not modified for C++11
-
- template <int pos, typename T1, typename T2> struct fold_on_zip_impl {
-  template <typename F, typename R>
-  auto operator()(F &&f, T1 const &t1, T2 const &t2, R &&r)DECL_AND_RETURN(fold_on_zip_impl<pos - 1, T1, T2>()(
-      std::forward<F>(f), t1, t2, f(std::get<pos>(t1), std::get<pos>(t2), std::forward<R>(r))));
- };
-
- template <typename T1, typename T2> struct fold_on_zip_impl<-1, T1, T2> {
-  template <typename F, typename R> R operator()(F &&f, T1 const &t1, T2 const &t2, R &&r) { return std::forward<R>(r); }
- };
-
- template <typename F, typename T1, typename T2, typename R>
- auto fold(F &&f, T1 const &t1, T2 const &t2, R &&r)
-     DECL_AND_RETURN(fold_on_zip_impl<std::tuple_size<T1>::value - 1, T1, T2>()(std::forward<F>(f), t1, t2, std::forward<R>(r)));
-
-#endif
 
  /**
   * replace<int ... I>(t,r)
@@ -527,4 +493,4 @@ auto get(c14::tuple<Args...> const &t) DECL_AND_RETURN(std::get<i>(static_cast<s
 
 template <typename... Args> class tuple_size<c14::tuple<Args...>> : public tuple_size<std::tuple<Args...>> {};
 }
-
+#endif