Upper bound on some sum

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Let $ngeq 1$, $epsilon>0$, $vin mathbbR^n$ and $c>0$. I want to prove that:
$$sum_k=1^n left|v^2_k+1-v^2_k right|sqrtepsilon frackn^frac13+c leq sqrtepsilonn^frac13sum_k=1^n (v_k+1-v_k)^2 + frac1sqrtepsilon n^frac13sum_k=1^n left(epsilon frackn^frac13+cright)v^2_k .$$



This is from a textbook I am currently studying. I understand that we get the v's on the RHS thanks to $v_k+1^2-v_k^2 leq (v_k+1-v_k)^2 + 2v_k+1v_k $ and Cauchy-Schwarz (applied on $v_k+1v_k$) but I am struggling for the whole bound.







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  • How can $k$ range from $1$ to $n$ for $|v_k+1-v_k|^2$ and $(v_k+1-v_k)^2$ when you only know values for $v_1, ldots, v_n$?
    – Tengu
    Jul 20 at 1:07










  • @Tengu by convention, one sets $v_0=v_n+1=0$.
    – anonymus
    Jul 20 at 17:48














up vote
0
down vote

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Let $ngeq 1$, $epsilon>0$, $vin mathbbR^n$ and $c>0$. I want to prove that:
$$sum_k=1^n left|v^2_k+1-v^2_k right|sqrtepsilon frackn^frac13+c leq sqrtepsilonn^frac13sum_k=1^n (v_k+1-v_k)^2 + frac1sqrtepsilon n^frac13sum_k=1^n left(epsilon frackn^frac13+cright)v^2_k .$$



This is from a textbook I am currently studying. I understand that we get the v's on the RHS thanks to $v_k+1^2-v_k^2 leq (v_k+1-v_k)^2 + 2v_k+1v_k $ and Cauchy-Schwarz (applied on $v_k+1v_k$) but I am struggling for the whole bound.







share|cite|improve this question



















  • How can $k$ range from $1$ to $n$ for $|v_k+1-v_k|^2$ and $(v_k+1-v_k)^2$ when you only know values for $v_1, ldots, v_n$?
    – Tengu
    Jul 20 at 1:07










  • @Tengu by convention, one sets $v_0=v_n+1=0$.
    – anonymus
    Jul 20 at 17:48












up vote
0
down vote

favorite









up vote
0
down vote

favorite











Let $ngeq 1$, $epsilon>0$, $vin mathbbR^n$ and $c>0$. I want to prove that:
$$sum_k=1^n left|v^2_k+1-v^2_k right|sqrtepsilon frackn^frac13+c leq sqrtepsilonn^frac13sum_k=1^n (v_k+1-v_k)^2 + frac1sqrtepsilon n^frac13sum_k=1^n left(epsilon frackn^frac13+cright)v^2_k .$$



This is from a textbook I am currently studying. I understand that we get the v's on the RHS thanks to $v_k+1^2-v_k^2 leq (v_k+1-v_k)^2 + 2v_k+1v_k $ and Cauchy-Schwarz (applied on $v_k+1v_k$) but I am struggling for the whole bound.







share|cite|improve this question











Let $ngeq 1$, $epsilon>0$, $vin mathbbR^n$ and $c>0$. I want to prove that:
$$sum_k=1^n left|v^2_k+1-v^2_k right|sqrtepsilon frackn^frac13+c leq sqrtepsilonn^frac13sum_k=1^n (v_k+1-v_k)^2 + frac1sqrtepsilon n^frac13sum_k=1^n left(epsilon frackn^frac13+cright)v^2_k .$$



This is from a textbook I am currently studying. I understand that we get the v's on the RHS thanks to $v_k+1^2-v_k^2 leq (v_k+1-v_k)^2 + 2v_k+1v_k $ and Cauchy-Schwarz (applied on $v_k+1v_k$) but I am struggling for the whole bound.









share|cite|improve this question










share|cite|improve this question




share|cite|improve this question









asked Jul 19 at 17:10









anonymus

854312




854312











  • How can $k$ range from $1$ to $n$ for $|v_k+1-v_k|^2$ and $(v_k+1-v_k)^2$ when you only know values for $v_1, ldots, v_n$?
    – Tengu
    Jul 20 at 1:07










  • @Tengu by convention, one sets $v_0=v_n+1=0$.
    – anonymus
    Jul 20 at 17:48
















  • How can $k$ range from $1$ to $n$ for $|v_k+1-v_k|^2$ and $(v_k+1-v_k)^2$ when you only know values for $v_1, ldots, v_n$?
    – Tengu
    Jul 20 at 1:07










  • @Tengu by convention, one sets $v_0=v_n+1=0$.
    – anonymus
    Jul 20 at 17:48















How can $k$ range from $1$ to $n$ for $|v_k+1-v_k|^2$ and $(v_k+1-v_k)^2$ when you only know values for $v_1, ldots, v_n$?
– Tengu
Jul 20 at 1:07




How can $k$ range from $1$ to $n$ for $|v_k+1-v_k|^2$ and $(v_k+1-v_k)^2$ when you only know values for $v_1, ldots, v_n$?
– Tengu
Jul 20 at 1:07












@Tengu by convention, one sets $v_0=v_n+1=0$.
– anonymus
Jul 20 at 17:48




@Tengu by convention, one sets $v_0=v_n+1=0$.
– anonymus
Jul 20 at 17:48















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