Relatively compact of minimizing sequences

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Let
$$
E(u)=frac12int_mathbb R^n |nabla u|^2-frac1p+1|u|^p+1 dx
$$
where $p$ is a positive constant. Define
$$
I_mu=inf.
$$
Assume $u_n$ is a minimizing sequence of $I_mu$, i.e.
$$
u_nin H^2(mathbb R^n),~~ ||u||_L^2^2=mu,~~
E(u_n)rightarrow I_mu.
$$
Why there are $y_nsubset mathbb R^n$ such that $u_n(cdot+y_n)$ is relatively compact
in $H^2(mathbb R^n)$ ?



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



This question is a doubt when I read the 552th page of Cazenave, T.; Lions, Pierre-Louis, Orbital stability of standing waves for some nonlinear Schrödinger equations, Commun. Math. Phys. 85, 549-561 (1982). ZBL0513.35007.










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  • Maybe your question is related to the concentration-compactness principle.
    – Rigel
    Sep 1 at 8:37










  • @Rigel Could you talk about it detail ? I know the concentration-compactness principle. But how to use it ?
    – lanse7pty
    Sep 1 at 8:53










  • Unfortunately I'm not able to help you. My observation is related to the "sperimental" fact that, almost every time one gets a sequence of the form $u_n(cdot + y_n)$, then at some point the concentration-compactness principle comes into action.
    – Rigel
    Sep 1 at 8:58











  • @Rigel Thanks your hint too.
    – lanse7pty
    Sep 1 at 12:43














up vote
2
down vote

favorite
1












Let
$$
E(u)=frac12int_mathbb R^n |nabla u|^2-frac1p+1|u|^p+1 dx
$$
where $p$ is a positive constant. Define
$$
I_mu=inf.
$$
Assume $u_n$ is a minimizing sequence of $I_mu$, i.e.
$$
u_nin H^2(mathbb R^n),~~ ||u||_L^2^2=mu,~~
E(u_n)rightarrow I_mu.
$$
Why there are $y_nsubset mathbb R^n$ such that $u_n(cdot+y_n)$ is relatively compact
in $H^2(mathbb R^n)$ ?



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



This question is a doubt when I read the 552th page of Cazenave, T.; Lions, Pierre-Louis, Orbital stability of standing waves for some nonlinear Schrödinger equations, Commun. Math. Phys. 85, 549-561 (1982). ZBL0513.35007.










share|cite|improve this question





















  • Maybe your question is related to the concentration-compactness principle.
    – Rigel
    Sep 1 at 8:37










  • @Rigel Could you talk about it detail ? I know the concentration-compactness principle. But how to use it ?
    – lanse7pty
    Sep 1 at 8:53










  • Unfortunately I'm not able to help you. My observation is related to the "sperimental" fact that, almost every time one gets a sequence of the form $u_n(cdot + y_n)$, then at some point the concentration-compactness principle comes into action.
    – Rigel
    Sep 1 at 8:58











  • @Rigel Thanks your hint too.
    – lanse7pty
    Sep 1 at 12:43












up vote
2
down vote

favorite
1









up vote
2
down vote

favorite
1






1





Let
$$
E(u)=frac12int_mathbb R^n |nabla u|^2-frac1p+1|u|^p+1 dx
$$
where $p$ is a positive constant. Define
$$
I_mu=inf.
$$
Assume $u_n$ is a minimizing sequence of $I_mu$, i.e.
$$
u_nin H^2(mathbb R^n),~~ ||u||_L^2^2=mu,~~
E(u_n)rightarrow I_mu.
$$
Why there are $y_nsubset mathbb R^n$ such that $u_n(cdot+y_n)$ is relatively compact
in $H^2(mathbb R^n)$ ?



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



This question is a doubt when I read the 552th page of Cazenave, T.; Lions, Pierre-Louis, Orbital stability of standing waves for some nonlinear Schrödinger equations, Commun. Math. Phys. 85, 549-561 (1982). ZBL0513.35007.










share|cite|improve this question













Let
$$
E(u)=frac12int_mathbb R^n |nabla u|^2-frac1p+1|u|^p+1 dx
$$
where $p$ is a positive constant. Define
$$
I_mu=inf.
$$
Assume $u_n$ is a minimizing sequence of $I_mu$, i.e.
$$
u_nin H^2(mathbb R^n),~~ ||u||_L^2^2=mu,~~
E(u_n)rightarrow I_mu.
$$
Why there are $y_nsubset mathbb R^n$ such that $u_n(cdot+y_n)$ is relatively compact
in $H^2(mathbb R^n)$ ?



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



This question is a doubt when I read the 552th page of Cazenave, T.; Lions, Pierre-Louis, Orbital stability of standing waves for some nonlinear Schrödinger equations, Commun. Math. Phys. 85, 549-561 (1982). ZBL0513.35007.







functional-analysis pde banach-spaces






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asked Sep 1 at 8:22









lanse7pty

1,7761723




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  • Maybe your question is related to the concentration-compactness principle.
    – Rigel
    Sep 1 at 8:37










  • @Rigel Could you talk about it detail ? I know the concentration-compactness principle. But how to use it ?
    – lanse7pty
    Sep 1 at 8:53










  • Unfortunately I'm not able to help you. My observation is related to the "sperimental" fact that, almost every time one gets a sequence of the form $u_n(cdot + y_n)$, then at some point the concentration-compactness principle comes into action.
    – Rigel
    Sep 1 at 8:58











  • @Rigel Thanks your hint too.
    – lanse7pty
    Sep 1 at 12:43
















  • Maybe your question is related to the concentration-compactness principle.
    – Rigel
    Sep 1 at 8:37










  • @Rigel Could you talk about it detail ? I know the concentration-compactness principle. But how to use it ?
    – lanse7pty
    Sep 1 at 8:53










  • Unfortunately I'm not able to help you. My observation is related to the "sperimental" fact that, almost every time one gets a sequence of the form $u_n(cdot + y_n)$, then at some point the concentration-compactness principle comes into action.
    – Rigel
    Sep 1 at 8:58











  • @Rigel Thanks your hint too.
    – lanse7pty
    Sep 1 at 12:43















Maybe your question is related to the concentration-compactness principle.
– Rigel
Sep 1 at 8:37




Maybe your question is related to the concentration-compactness principle.
– Rigel
Sep 1 at 8:37












@Rigel Could you talk about it detail ? I know the concentration-compactness principle. But how to use it ?
– lanse7pty
Sep 1 at 8:53




@Rigel Could you talk about it detail ? I know the concentration-compactness principle. But how to use it ?
– lanse7pty
Sep 1 at 8:53












Unfortunately I'm not able to help you. My observation is related to the "sperimental" fact that, almost every time one gets a sequence of the form $u_n(cdot + y_n)$, then at some point the concentration-compactness principle comes into action.
– Rigel
Sep 1 at 8:58





Unfortunately I'm not able to help you. My observation is related to the "sperimental" fact that, almost every time one gets a sequence of the form $u_n(cdot + y_n)$, then at some point the concentration-compactness principle comes into action.
– Rigel
Sep 1 at 8:58













@Rigel Thanks your hint too.
– lanse7pty
Sep 1 at 12:43




@Rigel Thanks your hint too.
– lanse7pty
Sep 1 at 12:43















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