Solve the nonlinear equation

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Suppose that $f:Eto F$(between Banach spaces), is of the form
$$f(x)=f(0)+D(x)+N(x).$$
Here $D$ is a linear term, whose kernel is of finite dimension, and admits a right inverse $G$, i.e. $D(G)(cdot)=Id_F$. The nonlinear term $N(x)$ satisfies that
$$|G(N(x))-G(N(y))|leq C(|x|+|y|)|x-y|$$



for some constant $C>0$ and $x,y$ in a small neighborhood $B_epsilon(C)(0)$.



Q: How to show that there is a unique zero point $x_0$ of $f$, i.e. $f(x_0)=0$, in $B_epsilon(0)cap G(F)$, with the initial condition $|G(f(0))|leqepsilon/2$?







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    What do you mean by a "zero point" of $f$? A fixed point, that is, $x_0$ such that $f(x_0) = x_0$? No, that can't be right since $f: E to F$; so then what? Cheers!
    – Robert Lewis
    Aug 6 at 1:18















up vote
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down vote

favorite
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Suppose that $f:Eto F$(between Banach spaces), is of the form
$$f(x)=f(0)+D(x)+N(x).$$
Here $D$ is a linear term, whose kernel is of finite dimension, and admits a right inverse $G$, i.e. $D(G)(cdot)=Id_F$. The nonlinear term $N(x)$ satisfies that
$$|G(N(x))-G(N(y))|leq C(|x|+|y|)|x-y|$$



for some constant $C>0$ and $x,y$ in a small neighborhood $B_epsilon(C)(0)$.



Q: How to show that there is a unique zero point $x_0$ of $f$, i.e. $f(x_0)=0$, in $B_epsilon(0)cap G(F)$, with the initial condition $|G(f(0))|leqepsilon/2$?







share|cite|improve this question

















  • 1




    What do you mean by a "zero point" of $f$? A fixed point, that is, $x_0$ such that $f(x_0) = x_0$? No, that can't be right since $f: E to F$; so then what? Cheers!
    – Robert Lewis
    Aug 6 at 1:18













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1
down vote

favorite
1









up vote
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down vote

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Suppose that $f:Eto F$(between Banach spaces), is of the form
$$f(x)=f(0)+D(x)+N(x).$$
Here $D$ is a linear term, whose kernel is of finite dimension, and admits a right inverse $G$, i.e. $D(G)(cdot)=Id_F$. The nonlinear term $N(x)$ satisfies that
$$|G(N(x))-G(N(y))|leq C(|x|+|y|)|x-y|$$



for some constant $C>0$ and $x,y$ in a small neighborhood $B_epsilon(C)(0)$.



Q: How to show that there is a unique zero point $x_0$ of $f$, i.e. $f(x_0)=0$, in $B_epsilon(0)cap G(F)$, with the initial condition $|G(f(0))|leqepsilon/2$?







share|cite|improve this question













Suppose that $f:Eto F$(between Banach spaces), is of the form
$$f(x)=f(0)+D(x)+N(x).$$
Here $D$ is a linear term, whose kernel is of finite dimension, and admits a right inverse $G$, i.e. $D(G)(cdot)=Id_F$. The nonlinear term $N(x)$ satisfies that
$$|G(N(x))-G(N(y))|leq C(|x|+|y|)|x-y|$$



for some constant $C>0$ and $x,y$ in a small neighborhood $B_epsilon(C)(0)$.



Q: How to show that there is a unique zero point $x_0$ of $f$, i.e. $f(x_0)=0$, in $B_epsilon(0)cap G(F)$, with the initial condition $|G(f(0))|leqepsilon/2$?









share|cite|improve this question












share|cite|improve this question




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edited Aug 7 at 13:47
























asked Aug 6 at 1:03









DLIN

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376314







  • 1




    What do you mean by a "zero point" of $f$? A fixed point, that is, $x_0$ such that $f(x_0) = x_0$? No, that can't be right since $f: E to F$; so then what? Cheers!
    – Robert Lewis
    Aug 6 at 1:18













  • 1




    What do you mean by a "zero point" of $f$? A fixed point, that is, $x_0$ such that $f(x_0) = x_0$? No, that can't be right since $f: E to F$; so then what? Cheers!
    – Robert Lewis
    Aug 6 at 1:18








1




1




What do you mean by a "zero point" of $f$? A fixed point, that is, $x_0$ such that $f(x_0) = x_0$? No, that can't be right since $f: E to F$; so then what? Cheers!
– Robert Lewis
Aug 6 at 1:18





What do you mean by a "zero point" of $f$? A fixed point, that is, $x_0$ such that $f(x_0) = x_0$? No, that can't be right since $f: E to F$; so then what? Cheers!
– Robert Lewis
Aug 6 at 1:18
















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