How is $C_0^k(mathbb R)$ defined?












3














I'm sorry for asking such a short question, but I see the space $C_0^k(mathbb R)$ everywhere being used without a rigorous definition.



$C_0(mathbb R)$ is the space of continuous functions on $mathbb R$ vanishing at infinity. The question is, is $C_0^k(mathbb R):=C_0(mathbb R)cap C^k(mathbb R)$ or is $C_0^k(mathbb R):=left{fin C^k(mathbb R):f^{(i)}in C_0(mathbb R)text{ for all }iinleft{0,ldots,kright}right}$?



Those spaces shouldn't coincide.










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    3














    I'm sorry for asking such a short question, but I see the space $C_0^k(mathbb R)$ everywhere being used without a rigorous definition.



    $C_0(mathbb R)$ is the space of continuous functions on $mathbb R$ vanishing at infinity. The question is, is $C_0^k(mathbb R):=C_0(mathbb R)cap C^k(mathbb R)$ or is $C_0^k(mathbb R):=left{fin C^k(mathbb R):f^{(i)}in C_0(mathbb R)text{ for all }iinleft{0,ldots,kright}right}$?



    Those spaces shouldn't coincide.










    share|cite|improve this question

























      3












      3








      3


      0





      I'm sorry for asking such a short question, but I see the space $C_0^k(mathbb R)$ everywhere being used without a rigorous definition.



      $C_0(mathbb R)$ is the space of continuous functions on $mathbb R$ vanishing at infinity. The question is, is $C_0^k(mathbb R):=C_0(mathbb R)cap C^k(mathbb R)$ or is $C_0^k(mathbb R):=left{fin C^k(mathbb R):f^{(i)}in C_0(mathbb R)text{ for all }iinleft{0,ldots,kright}right}$?



      Those spaces shouldn't coincide.










      share|cite|improve this question













      I'm sorry for asking such a short question, but I see the space $C_0^k(mathbb R)$ everywhere being used without a rigorous definition.



      $C_0(mathbb R)$ is the space of continuous functions on $mathbb R$ vanishing at infinity. The question is, is $C_0^k(mathbb R):=C_0(mathbb R)cap C^k(mathbb R)$ or is $C_0^k(mathbb R):=left{fin C^k(mathbb R):f^{(i)}in C_0(mathbb R)text{ for all }iinleft{0,ldots,kright}right}$?



      Those spaces shouldn't coincide.







      analysis derivatives






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      asked Nov 24 at 13:01









      0xbadf00d

      1,81441430




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          Correct definition is that $C_0^k(mathbb R):=left{fin C^k(mathbb R):f^{(i)}in C_0(mathbb R)text{ for all }iinleft{0,ldots,kright}right}$.



          If you write $C_c(Bbb R)$ set of all continuous function on $Bbb R$ with compact support then $C_c^k(mathbb R):=C_c(mathbb R)cap C^k(mathbb R)$.






          share|cite|improve this answer





















          • I follow the notation of the book "PSEUDO DIFFERENTIAL OPERATORS and MARKOV PROCESSES" written by N. Jacob. See page xiv for notation.
            – UserS
            Nov 24 at 13:42










          • $C_0(mathbb R)$ can be defined to be the closure of $C_c^infty(mathbb R)$ in $C_b(mathbb R)$ (bounded continuous functions on $mathbb R$. Is in the same way $C^k_0(mathbb R)$ the closure of $C_c^k(mathbb R)$ in $left{fin C^k(mathbb R):f^{(i)}text{ is bounded for all }iinleft{0,ldots,kright}right}$ equipped with $sum_{i=0}^kleft|f^{(i)}right|_infty$?
            – 0xbadf00d
            Nov 24 at 17:31













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          Correct definition is that $C_0^k(mathbb R):=left{fin C^k(mathbb R):f^{(i)}in C_0(mathbb R)text{ for all }iinleft{0,ldots,kright}right}$.



          If you write $C_c(Bbb R)$ set of all continuous function on $Bbb R$ with compact support then $C_c^k(mathbb R):=C_c(mathbb R)cap C^k(mathbb R)$.






          share|cite|improve this answer





















          • I follow the notation of the book "PSEUDO DIFFERENTIAL OPERATORS and MARKOV PROCESSES" written by N. Jacob. See page xiv for notation.
            – UserS
            Nov 24 at 13:42










          • $C_0(mathbb R)$ can be defined to be the closure of $C_c^infty(mathbb R)$ in $C_b(mathbb R)$ (bounded continuous functions on $mathbb R$. Is in the same way $C^k_0(mathbb R)$ the closure of $C_c^k(mathbb R)$ in $left{fin C^k(mathbb R):f^{(i)}text{ is bounded for all }iinleft{0,ldots,kright}right}$ equipped with $sum_{i=0}^kleft|f^{(i)}right|_infty$?
            – 0xbadf00d
            Nov 24 at 17:31


















          1














          Correct definition is that $C_0^k(mathbb R):=left{fin C^k(mathbb R):f^{(i)}in C_0(mathbb R)text{ for all }iinleft{0,ldots,kright}right}$.



          If you write $C_c(Bbb R)$ set of all continuous function on $Bbb R$ with compact support then $C_c^k(mathbb R):=C_c(mathbb R)cap C^k(mathbb R)$.






          share|cite|improve this answer





















          • I follow the notation of the book "PSEUDO DIFFERENTIAL OPERATORS and MARKOV PROCESSES" written by N. Jacob. See page xiv for notation.
            – UserS
            Nov 24 at 13:42










          • $C_0(mathbb R)$ can be defined to be the closure of $C_c^infty(mathbb R)$ in $C_b(mathbb R)$ (bounded continuous functions on $mathbb R$. Is in the same way $C^k_0(mathbb R)$ the closure of $C_c^k(mathbb R)$ in $left{fin C^k(mathbb R):f^{(i)}text{ is bounded for all }iinleft{0,ldots,kright}right}$ equipped with $sum_{i=0}^kleft|f^{(i)}right|_infty$?
            – 0xbadf00d
            Nov 24 at 17:31
















          1












          1








          1






          Correct definition is that $C_0^k(mathbb R):=left{fin C^k(mathbb R):f^{(i)}in C_0(mathbb R)text{ for all }iinleft{0,ldots,kright}right}$.



          If you write $C_c(Bbb R)$ set of all continuous function on $Bbb R$ with compact support then $C_c^k(mathbb R):=C_c(mathbb R)cap C^k(mathbb R)$.






          share|cite|improve this answer












          Correct definition is that $C_0^k(mathbb R):=left{fin C^k(mathbb R):f^{(i)}in C_0(mathbb R)text{ for all }iinleft{0,ldots,kright}right}$.



          If you write $C_c(Bbb R)$ set of all continuous function on $Bbb R$ with compact support then $C_c^k(mathbb R):=C_c(mathbb R)cap C^k(mathbb R)$.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Nov 24 at 13:39









          UserS

          1,5371112




          1,5371112












          • I follow the notation of the book "PSEUDO DIFFERENTIAL OPERATORS and MARKOV PROCESSES" written by N. Jacob. See page xiv for notation.
            – UserS
            Nov 24 at 13:42










          • $C_0(mathbb R)$ can be defined to be the closure of $C_c^infty(mathbb R)$ in $C_b(mathbb R)$ (bounded continuous functions on $mathbb R$. Is in the same way $C^k_0(mathbb R)$ the closure of $C_c^k(mathbb R)$ in $left{fin C^k(mathbb R):f^{(i)}text{ is bounded for all }iinleft{0,ldots,kright}right}$ equipped with $sum_{i=0}^kleft|f^{(i)}right|_infty$?
            – 0xbadf00d
            Nov 24 at 17:31




















          • I follow the notation of the book "PSEUDO DIFFERENTIAL OPERATORS and MARKOV PROCESSES" written by N. Jacob. See page xiv for notation.
            – UserS
            Nov 24 at 13:42










          • $C_0(mathbb R)$ can be defined to be the closure of $C_c^infty(mathbb R)$ in $C_b(mathbb R)$ (bounded continuous functions on $mathbb R$. Is in the same way $C^k_0(mathbb R)$ the closure of $C_c^k(mathbb R)$ in $left{fin C^k(mathbb R):f^{(i)}text{ is bounded for all }iinleft{0,ldots,kright}right}$ equipped with $sum_{i=0}^kleft|f^{(i)}right|_infty$?
            – 0xbadf00d
            Nov 24 at 17:31


















          I follow the notation of the book "PSEUDO DIFFERENTIAL OPERATORS and MARKOV PROCESSES" written by N. Jacob. See page xiv for notation.
          – UserS
          Nov 24 at 13:42




          I follow the notation of the book "PSEUDO DIFFERENTIAL OPERATORS and MARKOV PROCESSES" written by N. Jacob. See page xiv for notation.
          – UserS
          Nov 24 at 13:42












          $C_0(mathbb R)$ can be defined to be the closure of $C_c^infty(mathbb R)$ in $C_b(mathbb R)$ (bounded continuous functions on $mathbb R$. Is in the same way $C^k_0(mathbb R)$ the closure of $C_c^k(mathbb R)$ in $left{fin C^k(mathbb R):f^{(i)}text{ is bounded for all }iinleft{0,ldots,kright}right}$ equipped with $sum_{i=0}^kleft|f^{(i)}right|_infty$?
          – 0xbadf00d
          Nov 24 at 17:31






          $C_0(mathbb R)$ can be defined to be the closure of $C_c^infty(mathbb R)$ in $C_b(mathbb R)$ (bounded continuous functions on $mathbb R$. Is in the same way $C^k_0(mathbb R)$ the closure of $C_c^k(mathbb R)$ in $left{fin C^k(mathbb R):f^{(i)}text{ is bounded for all }iinleft{0,ldots,kright}right}$ equipped with $sum_{i=0}^kleft|f^{(i)}right|_infty$?
          – 0xbadf00d
          Nov 24 at 17:31




















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