/usr/include/CGAL/Optimisation/ is in libcgal-dev 4.2-5ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/CGAL/Optimisation/Access_coordinates_begin_2.h
/usr/include/CGAL/Optimisation/Access_coordinates_begin_3.h
/usr/include/CGAL/Optimisation/Access_coordinates_begin_d.h
/usr/include/CGAL/Optimisation/Access_dimension_2.h
/usr/include/CGAL/Optimisation/Access_dimension_3.h
/usr/include/CGAL/Optimisation/Access_dimension_d.h
/usr/include/CGAL/Optimisation/Construct_point_2.h
/usr/include/CGAL/Optimisation/Construct_point_3.h
/usr/include/CGAL/Optimisation/Construct_point_d.h
/usr/include/CGAL/Optimisation/assertions.h
/usr/include/CGAL/Optimisation/basic.h
/usr/include/CGAL/Optimisation/debug.h