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diff --git a/include/gudhi/Skeleton_blocker/internal/Top_faces.h b/include/gudhi/Skeleton_blocker/internal/Top_faces.h
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+++ b/include/gudhi/Skeleton_blocker/internal/Top_faces.h
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+/*    This file is part of the Gudhi Library. The Gudhi library
+ *    (Geometric Understanding in Higher Dimensions) is a generic C++
+ *    library for computational topology.
+ *
+ *    Author(s):       David Salinas
+ *
+ *    Copyright (C) 2014  INRIA Sophia Antipolis-Mediterranee (France)
+ *
+ *    This program 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.
+ *
+ *    This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef SKELETON_BLOCKER_INTERNAL_TOP_FACES_H_
+#define SKELETON_BLOCKER_INTERNAL_TOP_FACES_H_
+
+#include <list>
+#include <vector>
+#include <set>
+
+namespace Gudhi {
+
+namespace skeleton_blocker {
+
+template<typename SimplexHandle>
+std::list<SimplexHandle> subfaces(SimplexHandle top_face) {
+  std::list<SimplexHandle> res;
+  if (top_face.dimension() == -1) return res;
+  if (top_face.dimension() == 0) {
+    res.push_back(top_face);
+    return res;
+  } else {
+    auto first_vertex = top_face.first_vertex();
+    top_face.remove_vertex(first_vertex);
+    res = subfaces(top_face);
+    std::list<SimplexHandle> copy = res;
+    for (auto& simplex : copy) {
+      simplex.add_vertex(first_vertex);
+    }
+    res.push_back(SimplexHandle(first_vertex));
+    res.splice(res.end(), copy);
+    return res;
+  }
+}
+
+/**
+ * add all faces of top_face in simplices_per_dimension
+ */
+template<typename SimplexHandle>
+void register_faces(std::vector< std::set<SimplexHandle> >& simplices_per_dimension,
+                    const SimplexHandle& top_face) {
+  std::list<SimplexHandle> subfaces_list = subfaces(top_face);
+  for (auto& simplex : subfaces_list) {
+    simplices_per_dimension[simplex.dimension()].insert(simplex);
+  }
+}
+
+}  // namespace skeleton_blocker
+
+namespace skbl = skeleton_blocker;
+
+}  // namespace Gudhi
+
+#endif  // SKELETON_BLOCKER_INTERNAL_TOP_FACES_H_