\BOOKMARK [1][-]{section.1}{Introduction}{}% 1
\BOOKMARK [1][-]{section.2}{The main results}{}% 2
\BOOKMARK [1][-]{section.3}{The preliminary results}{}% 3
\BOOKMARK [1][-]{section.4}{Additional properties of the inner sum}{}% 4
\BOOKMARK [1][-]{section.5}{The proofs of the main results}{}% 5
\BOOKMARK [1][-]{section.6}{Concluding remark}{}% 6