An integral estimate in conformal geometry












3












$begingroup$


Let $g_0$ be a Riemannian metric of positive scalar curvature $R_0$ on a closed 4-manifold, and for some fixed constant $C$, define the set
begin{equation}
mathcal{S} = {uin C^infty(M): ||u||_{W^{1,12}(M)}leq C}.
end{equation}

Then consider the set of conformal metrics
begin{equation}
mathcal{T} = {g=e^{2u}g_0:uinmathcal{S},~R_ggeq C(g_0)>0}.
end{equation}

The motivation behind this is I have a set of smooth solutions $u$ satisfying some PDE, for which I have uniform $W^{1,12}$ estimates and know that the corresponding scalar curvatures are uniformly bounded (i.e. a bound depending only on $g_0$) away from zero.



I am trying to obtain the following estimate:



begin{equation}tag{1}
int R^p|nabla^2 u|^4|nabla u|^4 ,dv_gleq Cint R^{p+6},dv_g + C
end{equation}

where $C$ again depends only on $g_0$. When $p>0$ I have no problem: the conformal transformation law for the scalar curvature implies



begin{equation}
|R|leq CBig(|R_0| + |nabla u|^2 + |Delta u|Big)\
implies|R|^p leq CBig(|R_0|^p + |nabla u|^{2p} + |Delta u|^pBig)
end{equation}



for some uniform $C$, and we can plug this into $(1)$ and apply Holder etc. But when $p<0$, I am really stuck - one attempt is to use $R^{-1}leq C$ (which follows from $Rgeq C>0$), but then I'm not sure how to reintroduce to scalar curvature to get something like $(1)$. Any help would be much appreciated. Thanks!










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migrated from math.stackexchange.com Dec 23 '18 at 0:32


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  • 1




    $begingroup$
    This is a bit specialistic, if you do not obtain answers consider flagging for migration to MathOverflow.
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    – Giuseppe Negro
    Dec 17 '18 at 10:34
















3












$begingroup$


Let $g_0$ be a Riemannian metric of positive scalar curvature $R_0$ on a closed 4-manifold, and for some fixed constant $C$, define the set
begin{equation}
mathcal{S} = {uin C^infty(M): ||u||_{W^{1,12}(M)}leq C}.
end{equation}

Then consider the set of conformal metrics
begin{equation}
mathcal{T} = {g=e^{2u}g_0:uinmathcal{S},~R_ggeq C(g_0)>0}.
end{equation}

The motivation behind this is I have a set of smooth solutions $u$ satisfying some PDE, for which I have uniform $W^{1,12}$ estimates and know that the corresponding scalar curvatures are uniformly bounded (i.e. a bound depending only on $g_0$) away from zero.



I am trying to obtain the following estimate:



begin{equation}tag{1}
int R^p|nabla^2 u|^4|nabla u|^4 ,dv_gleq Cint R^{p+6},dv_g + C
end{equation}

where $C$ again depends only on $g_0$. When $p>0$ I have no problem: the conformal transformation law for the scalar curvature implies



begin{equation}
|R|leq CBig(|R_0| + |nabla u|^2 + |Delta u|Big)\
implies|R|^p leq CBig(|R_0|^p + |nabla u|^{2p} + |Delta u|^pBig)
end{equation}



for some uniform $C$, and we can plug this into $(1)$ and apply Holder etc. But when $p<0$, I am really stuck - one attempt is to use $R^{-1}leq C$ (which follows from $Rgeq C>0$), but then I'm not sure how to reintroduce to scalar curvature to get something like $(1)$. Any help would be much appreciated. Thanks!










share|cite|improve this question









$endgroup$



migrated from math.stackexchange.com Dec 23 '18 at 0:32


This question came from our site for people studying math at any level and professionals in related fields.














  • 1




    $begingroup$
    This is a bit specialistic, if you do not obtain answers consider flagging for migration to MathOverflow.
    $endgroup$
    – Giuseppe Negro
    Dec 17 '18 at 10:34














3












3








3





$begingroup$


Let $g_0$ be a Riemannian metric of positive scalar curvature $R_0$ on a closed 4-manifold, and for some fixed constant $C$, define the set
begin{equation}
mathcal{S} = {uin C^infty(M): ||u||_{W^{1,12}(M)}leq C}.
end{equation}

Then consider the set of conformal metrics
begin{equation}
mathcal{T} = {g=e^{2u}g_0:uinmathcal{S},~R_ggeq C(g_0)>0}.
end{equation}

The motivation behind this is I have a set of smooth solutions $u$ satisfying some PDE, for which I have uniform $W^{1,12}$ estimates and know that the corresponding scalar curvatures are uniformly bounded (i.e. a bound depending only on $g_0$) away from zero.



I am trying to obtain the following estimate:



begin{equation}tag{1}
int R^p|nabla^2 u|^4|nabla u|^4 ,dv_gleq Cint R^{p+6},dv_g + C
end{equation}

where $C$ again depends only on $g_0$. When $p>0$ I have no problem: the conformal transformation law for the scalar curvature implies



begin{equation}
|R|leq CBig(|R_0| + |nabla u|^2 + |Delta u|Big)\
implies|R|^p leq CBig(|R_0|^p + |nabla u|^{2p} + |Delta u|^pBig)
end{equation}



for some uniform $C$, and we can plug this into $(1)$ and apply Holder etc. But when $p<0$, I am really stuck - one attempt is to use $R^{-1}leq C$ (which follows from $Rgeq C>0$), but then I'm not sure how to reintroduce to scalar curvature to get something like $(1)$. Any help would be much appreciated. Thanks!










share|cite|improve this question









$endgroup$




Let $g_0$ be a Riemannian metric of positive scalar curvature $R_0$ on a closed 4-manifold, and for some fixed constant $C$, define the set
begin{equation}
mathcal{S} = {uin C^infty(M): ||u||_{W^{1,12}(M)}leq C}.
end{equation}

Then consider the set of conformal metrics
begin{equation}
mathcal{T} = {g=e^{2u}g_0:uinmathcal{S},~R_ggeq C(g_0)>0}.
end{equation}

The motivation behind this is I have a set of smooth solutions $u$ satisfying some PDE, for which I have uniform $W^{1,12}$ estimates and know that the corresponding scalar curvatures are uniformly bounded (i.e. a bound depending only on $g_0$) away from zero.



I am trying to obtain the following estimate:



begin{equation}tag{1}
int R^p|nabla^2 u|^4|nabla u|^4 ,dv_gleq Cint R^{p+6},dv_g + C
end{equation}

where $C$ again depends only on $g_0$. When $p>0$ I have no problem: the conformal transformation law for the scalar curvature implies



begin{equation}
|R|leq CBig(|R_0| + |nabla u|^2 + |Delta u|Big)\
implies|R|^p leq CBig(|R_0|^p + |nabla u|^{2p} + |Delta u|^pBig)
end{equation}



for some uniform $C$, and we can plug this into $(1)$ and apply Holder etc. But when $p<0$, I am really stuck - one attempt is to use $R^{-1}leq C$ (which follows from $Rgeq C>0$), but then I'm not sure how to reintroduce to scalar curvature to get something like $(1)$. Any help would be much appreciated. Thanks!







dg.differential-geometry riemannian-geometry curvature conformal-geometry






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asked Dec 13 '18 at 23:26









jl2jl2

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migrated from math.stackexchange.com Dec 23 '18 at 0:32


This question came from our site for people studying math at any level and professionals in related fields.









migrated from math.stackexchange.com Dec 23 '18 at 0:32


This question came from our site for people studying math at any level and professionals in related fields.










  • 1




    $begingroup$
    This is a bit specialistic, if you do not obtain answers consider flagging for migration to MathOverflow.
    $endgroup$
    – Giuseppe Negro
    Dec 17 '18 at 10:34














  • 1




    $begingroup$
    This is a bit specialistic, if you do not obtain answers consider flagging for migration to MathOverflow.
    $endgroup$
    – Giuseppe Negro
    Dec 17 '18 at 10:34








1




1




$begingroup$
This is a bit specialistic, if you do not obtain answers consider flagging for migration to MathOverflow.
$endgroup$
– Giuseppe Negro
Dec 17 '18 at 10:34




$begingroup$
This is a bit specialistic, if you do not obtain answers consider flagging for migration to MathOverflow.
$endgroup$
– Giuseppe Negro
Dec 17 '18 at 10:34










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