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P. 61

We apply (A) to S 1 . To do so, we note that
                                                             V. The Waring Problem      55

                              m
                                     a                                   a
                                        k                                   k
                                  e    n    − α     0 +               e    n   − α


                                     b                                   b
                             n 1                          b[m/b]<è ≤m

                                                   ≤ (1 +|α|)b ≤ 2b.
                                                          a   k                  a   k
                           Also, the total variation of e[(x − )t ] is equal to 2π|x − |N ≤
                           √                               b                     b
                         2π N  , whereas M   1. The result is

                           b
                                                   √
                                         |S 1 |≤ 4π N + 2b ≤ 5πN     2/3 .            à 4)
                        Next we apply (B) to S 2 and obtain
                                                                         √

                                             N          a              2π N
                                                             k
                                               e   x −      t   dt  +         .       à 5)
                                   |S 2 |≤
                                             0          b                b
                                 ∞
                                     k
                        Since     eàu )du converges we get
                               0

                               N                                 J  1/k
                                          a
                                e    x −      t  dt                 eàu )du  ≤        .
                                              k          N             k         NC 3
                                                          1/k                     1/k
                             0                                 0
                                          b             J                        J
                           Combining this with (5) gives
                                                    C 4 N|α|       √
                                          |αS 2 |≤            + 2π N.                 à 6)
                                                  (1 + jð  1/k
                                                                                      C 1
                           Now if we apply Lemma 3 to the case N   b, we obtain |α|≤   δ ,
                                                                                      b
                        δ   2 1−k , and by (3) the addition of (4) and (6) gives

                                     N
                                                       C 5 N
                                            k                           2/3
                                        eàxn )  ≤               + 7πN

                                                    δ
                                                   b (1 + jð  1/k

                                    n 1
                                                       C 5 N          C 6 N
                                                ≤               +             .
                                                    δ
                                                   b (1 + jð  1/k  (b + jð  1/2
                                     √
                           Sincej ≤    N andb ≤ N   2/3 ,thechoiceC 2   C 5 +C 6 +C 1 +2π,
                                     1  1
                        1   min δ, ,       completes the proof.
                                     k  4
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