Generalized Ordinary Differential Equations in Abstract Spaces and Applications. Группа авторов

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Generalized Ordinary Differential Equations in Abstract Spaces and Applications - Группа авторов

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comma b right-bracket comma upper X right-parenthesis equals script upper L 1 left-parenthesis left-bracket a comma b right-bracket comma upper X right-parenthesis period"/>

      We will prove this equality in the sequel. Furthermore, italic upper H upper M upper S left-parenthesis left-bracket a comma b right-bracket comma upper X right-parenthesis subset-of upper H left-parenthesis left-bracket a comma b right-bracket comma upper X right-parenthesis, italic upper K upper M upper S left-parenthesis left-bracket a comma b right-bracket comma upper X right-parenthesis subset-of upper K left-parenthesis left-bracket a comma b right-bracket comma upper X right-parenthesis comma and italic RMS left-parenthesis left-bracket a comma b right-bracket comma upper X right-parenthesis subset-of upper R left-parenthesis left-bracket a comma b right-bracket comma upper X right-parenthesis, where we use the notation italic upper K upper M upper S left-parenthesis left-bracket a comma b right-bracket comma upper X right-parenthesis and italic RMS left-parenthesis left-bracket a comma b right-bracket comma upper X right-parenthesis to denote, respectively, the spaces of Kurzweil–McShane and Riemann–McShane integrable functions from left-bracket a comma b right-bracket to upper X. For other interesting results, the reader may want to consult [55].

      Lemma 1.93: Let be a sequence in and be a function. Suppose there exists

limit Underscript n right-arrow infinity Endscripts left-parenthesis italic upper K upper M upper S right-parenthesis integral Subscript a Superscript b Baseline vertical-bar vertical-bar vertical-bar vertical-bar minus minus of ffn left-parenthesis right-parenthesis t of ff left-parenthesis right-parenthesis t d t equals 0 period

       Then, and

limit Underscript n right-arrow infinity Endscripts left-parenthesis italic upper K upper M upper S right-parenthesis integral Subscript a Superscript b Baseline f Subscript n Baseline left-parenthesis t right-parenthesis d t equals left-parenthesis italic upper K upper M upper S right-parenthesis integral Subscript a Superscript b Baseline f left-parenthesis t right-parenthesis d t period

      Proof. Given epsilon greater-than 0, take n Subscript epsilon such that for m comma n greater-than-or-slanted-equals n Subscript epsilon Baseline,

left-parenthesis italic upper K upper M upper S right-parenthesis integral Subscript a Superscript b Baseline vertical-bar vertical-bar vertical-bar vertical-bar minus minus of ffn left-parenthesis right-parenthesis t of ffm left-parenthesis right-parenthesis t d t less-than epsilon

      and take a gauge delta on left-bracket a comma b right-bracket such that for every delta-fine d equals left-parenthesis xi Subscript i Baseline comma left-bracket t Subscript i minus 1 Baseline comma t Subscript i Baseline right-bracket right-parenthesis element-of upper S upper T upper D Subscript left-bracket a comma b right-bracket,

      The limit upper I equals limit Underscript n right-arrow infinity Endscripts left-parenthesis italic upper K upper M upper S right-parenthesis integral Subscript a Superscript b Baseline f Subscript n Baseline left-parenthesis t right-parenthesis d t exists, since for m comma n greater-than-or-slanted-equals n Subscript epsilon Baseline,

StartLayout 1st Row 1st Column Blank 2nd Column vertical-bar vertical-bar vertical-bar vertical-bar minus minus times times left-parenthesis right-parenthesis KMS integral integral ab of ffn left-parenthesis right-parenthesis t separator d separator t times times left-parenthesis right-parenthesis KMS integral integral ab of ffm left-parenthesis right-parenthesis t separator d separator t 2nd Row 1st Column Blank 2nd Column less-than-or-slanted-equals left-parenthesis italic upper K upper M upper S right-parenthesis integral Subscript a Superscript b Baseline vertical-bar vertical-bar vertical-bar vertical-bar minus minus of ffn left-parenthesis right-parenthesis t of ff left-parenthesis right-parenthesis t d t plus left-parenthesis italic upper K upper M upper S right-parenthesis integral Subscript a Superscript b Baseline vertical-bar vertical-bar vertical-bar vertical-bar minus minus of ff left-parenthesis right-parenthesis t of ffm left-parenthesis right-parenthesis t d t less-than-or-slanted-equals 2 epsilon period EndLayout

      Hence, if upper I Subscript n Baseline equals left-parenthesis italic upper K upper M upper S right-parenthesis integral Subscript a Superscript b Baseline f Subscript n Baseline left-parenthesis t right-parenthesis d t, then

StartLayout 1st Row 1st Column Blank 2nd Column vertical-bar vertical-bar vertical-bar vertical-bar minus minus sigma-summation sigma-summation equals equals i 1 vertical-bar vertical-bar d times times of ff left-parenthesis right-parenthesis xi i left-parenthesis right-parenthesis minus minus tit minus minus i 1 upper I 2nd Row 1st Column Blank 2nd Column less-than-or-slanted-equals sigma-summation Underscript i equals 1 Overscript StartAbsoluteValue d EndAbsoluteValue Endscripts vertical-bar vertical-bar vertical-bar vertical-bar minus minus of ff left-parenthesis right-parenthesis xi i of ffn epsilon left-parenthesis right-parenthesis xi i left-parenthesis t Subscript i Baseline minus t Subscript i minus 1 Baseline right-parenthesis plus vertical-bar vertical-bar vertical-bar vertical-bar minus minus sigma-summation sigma-summation equals equals i 1 vertical-bar vertical-bar d times times of ffn epsilon left-parenthesis right-parenthesis xi i left-parenthesis right-parenthesis minus minus tit minus minus i 1 In epsilon plus vertical-bar vertical-bar vertical-bar vertical-bar minus minus In epsilon upper I period EndLayout

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