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Controllability of Single-valued Chapter | 7  193


                The approximate controllability of the considered system (7.1) (7.2) is
             studied under the following hypotheses

                (H 1 ) A generates an  t  α21  ; 1 -regularized family S α ðtÞ such that there
                                   ΓðαÞ
                exist ω . 0 and M . 0 such that
                                               ωt
                                    OS α ðtÞO # Me ; ’tAJ:
                (H 2 ) For each ðt; sÞAJ 3 J, the function gðt; s; UÞ:B-H is continuous and
                for each φAB the function gðU; U; φÞ:J 3 J-H is strongly measurable.
                (H 3 ) The multivalued map F:J 3 B 3 H-P bd;cl;cv ðHÞ satisfies the follow-
                ing conditions
                (i) for each tAJ, the map Fðt; U; UÞ:B 3 H-P bd;cl;cv ðHÞ is u.s.c.
               (ii) for each ðφ; yÞAB 3 H, the map FðU; φ; yÞ:J-P bd;cl;cv ðHÞ is measur-
                   able and the set

                                                ð  t
                              1
                   N F;φ 5 fAL ðJ; HÞ: fðtÞAFt; φ;  gðt; s; φÞds  for a:etAJ
                                                 0
               is nonempty.
                (H 4 ) For each positive number r . 0, there exists a positive function μðrÞ
                depending on r such that

                                      ^
                                         2
                          sup OFðt; φ; LφÞO # μðrÞ;  lim  μðrÞ  5 δ , N
                           2
                         OφO # r                   r-N r
                           B
                                    ^
               and there exists constant d . 0 such that
                                            EOFðt; φ; LφÞO
                                                    ^   2
                                                             ^
                             0 #   lim   sup       2      # d:
                                 OφO -N  tAJ    OφO
                                   2
                                   B               B
                (H 5 ) The function σ:J 3 J 3 B-LðK; HÞ satisfies the following
                (i) for each ðt; sÞAJ 3 J, the function σðt; s; UÞ:B-LðK; HÞ is continuous
                   and for each φAB, the function σðU; U; φÞ:J 3 J-LðK; HÞ is strongly
                   measurable.
                                                       1
               (ii) there is a positive integrable function mAL ð½0;bŠÞ and a continuous
                   nondecreasing function Λ σ : ½0;NÞ-ð0;NÞ such that for every
                   ðt; s; xÞAJ 3 J 3 B, we have
                     ð t                                Λ σ ð4rÞ
                                               2
                                2
                       EOσðt; s; xÞO ds # mðtÞΛ σ ðOxO Þ;  lim  5 Δ , N:
                                Q              B
                     0                              r-N   r
                (H 6 ) The linear system corresponding to the fractional order system
                (7.1) (7.2) is approximately controllable.
                (H 7 ) The functions Fðt; ψ; yÞ:J 3 B 3 H-P bd;cl;cv ðHÞ; gðt; s; ψÞ:J 3 J 3
                B-H; and σðt; s; ψÞ:J 3 J 3 B-LðK; HÞ are uniformly bounded for all
                tAJ; ψAB and yAH.
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