How are the two versions of the Lumer-Phillips theorem given in the books of Engel/Nagel and Pazy related? ...
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How are the two versions of the Lumer-Phillips theorem given in the books of Engel/Nagel and Pazy related?
The Next CEO of Stack OverflowNecessary and sufficient condition of being dissipativeShowing that an operator generates a contraction semigroupFind the iverse of the followning bounded operator?Proving the existence of a solution of the heat equation using semigroup methodsLumer-Phillips Theorem for non-contraction semigroups?If it holds that $forall f in mathcal{D}(A): T(t)f-f = int_0^t T(s) Af ds$ then $A$ is the generator of ${T(t)}$Proving density of $H^2(mathbb{R})$ in $L^2(mathbb{R})$ .Proving an operator is surjective for Lumer-Phillips Theorem application.Understanding a proof from Pazy's book on infinitesimal generatorsShowing that $lambda - (A + B)$ has dense range
$begingroup$
Let $E$ be a $mathbb R$-Banach space and $(mathcal D(A),A)$ be a densely-defined dissipative linear operator on $E$.
In the book of Engel and Nagel, I've found the following verison of the Lumer-Phillips theorem:
Version 1: The closure $(mathcal D(overline A),overline A)$ of $(mathcal D(A),A)$ is the generator of a contraction semigroup if and only if $lambdaoperatorname{id}_{mathcal D(A)}-A$ has dense range for some (and hence all) $lambda>0$.
Now, in the book of Pazy, I've found a different version:
Version 2: The range of $lambdaoperatorname{id}_{mathcal D(A)}-A$ is $E$ for some $lambda>0$ if and only if $(mathcal D(A),A)$ is the generator of a strongly continuous contraction semigroup.
Question 1: How are these two versions related? For example, if $(mathcal D(A),A)$ is the generator of a contraction semigroup, version 1 only yields that $lambdaoperatorname{id}_{mathcal D(A)}-A$ has dense range for all $lambda>0$. How do we see that these ranges are actually the whole space $E$? Clearly, the crucial thing must be that not only the closure $(mathcal D(overline A),overline A)$ but $(mathcal D(A),A)$ itself is the generator of a contraction semigroup.
Question 2: In version 1, there is no strong continuity claim on the semigroup. Is this a mistake in the book or are we not able to conclude the strong continuity of the contraction semigroup generated by $(mathcal D(overline A),overline A)$ if $lambdaoperatorname{id}_{mathcal D(A)}-A$ has dense range for some $lambda>0$?
functional-analysis operator-theory semigroup-of-operators
$endgroup$
add a comment |
$begingroup$
Let $E$ be a $mathbb R$-Banach space and $(mathcal D(A),A)$ be a densely-defined dissipative linear operator on $E$.
In the book of Engel and Nagel, I've found the following verison of the Lumer-Phillips theorem:
Version 1: The closure $(mathcal D(overline A),overline A)$ of $(mathcal D(A),A)$ is the generator of a contraction semigroup if and only if $lambdaoperatorname{id}_{mathcal D(A)}-A$ has dense range for some (and hence all) $lambda>0$.
Now, in the book of Pazy, I've found a different version:
Version 2: The range of $lambdaoperatorname{id}_{mathcal D(A)}-A$ is $E$ for some $lambda>0$ if and only if $(mathcal D(A),A)$ is the generator of a strongly continuous contraction semigroup.
Question 1: How are these two versions related? For example, if $(mathcal D(A),A)$ is the generator of a contraction semigroup, version 1 only yields that $lambdaoperatorname{id}_{mathcal D(A)}-A$ has dense range for all $lambda>0$. How do we see that these ranges are actually the whole space $E$? Clearly, the crucial thing must be that not only the closure $(mathcal D(overline A),overline A)$ but $(mathcal D(A),A)$ itself is the generator of a contraction semigroup.
Question 2: In version 1, there is no strong continuity claim on the semigroup. Is this a mistake in the book or are we not able to conclude the strong continuity of the contraction semigroup generated by $(mathcal D(overline A),overline A)$ if $lambdaoperatorname{id}_{mathcal D(A)}-A$ has dense range for some $lambda>0$?
functional-analysis operator-theory semigroup-of-operators
$endgroup$
add a comment |
$begingroup$
Let $E$ be a $mathbb R$-Banach space and $(mathcal D(A),A)$ be a densely-defined dissipative linear operator on $E$.
In the book of Engel and Nagel, I've found the following verison of the Lumer-Phillips theorem:
Version 1: The closure $(mathcal D(overline A),overline A)$ of $(mathcal D(A),A)$ is the generator of a contraction semigroup if and only if $lambdaoperatorname{id}_{mathcal D(A)}-A$ has dense range for some (and hence all) $lambda>0$.
Now, in the book of Pazy, I've found a different version:
Version 2: The range of $lambdaoperatorname{id}_{mathcal D(A)}-A$ is $E$ for some $lambda>0$ if and only if $(mathcal D(A),A)$ is the generator of a strongly continuous contraction semigroup.
Question 1: How are these two versions related? For example, if $(mathcal D(A),A)$ is the generator of a contraction semigroup, version 1 only yields that $lambdaoperatorname{id}_{mathcal D(A)}-A$ has dense range for all $lambda>0$. How do we see that these ranges are actually the whole space $E$? Clearly, the crucial thing must be that not only the closure $(mathcal D(overline A),overline A)$ but $(mathcal D(A),A)$ itself is the generator of a contraction semigroup.
Question 2: In version 1, there is no strong continuity claim on the semigroup. Is this a mistake in the book or are we not able to conclude the strong continuity of the contraction semigroup generated by $(mathcal D(overline A),overline A)$ if $lambdaoperatorname{id}_{mathcal D(A)}-A$ has dense range for some $lambda>0$?
functional-analysis operator-theory semigroup-of-operators
$endgroup$
Let $E$ be a $mathbb R$-Banach space and $(mathcal D(A),A)$ be a densely-defined dissipative linear operator on $E$.
In the book of Engel and Nagel, I've found the following verison of the Lumer-Phillips theorem:
Version 1: The closure $(mathcal D(overline A),overline A)$ of $(mathcal D(A),A)$ is the generator of a contraction semigroup if and only if $lambdaoperatorname{id}_{mathcal D(A)}-A$ has dense range for some (and hence all) $lambda>0$.
Now, in the book of Pazy, I've found a different version:
Version 2: The range of $lambdaoperatorname{id}_{mathcal D(A)}-A$ is $E$ for some $lambda>0$ if and only if $(mathcal D(A),A)$ is the generator of a strongly continuous contraction semigroup.
Question 1: How are these two versions related? For example, if $(mathcal D(A),A)$ is the generator of a contraction semigroup, version 1 only yields that $lambdaoperatorname{id}_{mathcal D(A)}-A$ has dense range for all $lambda>0$. How do we see that these ranges are actually the whole space $E$? Clearly, the crucial thing must be that not only the closure $(mathcal D(overline A),overline A)$ but $(mathcal D(A),A)$ itself is the generator of a contraction semigroup.
Question 2: In version 1, there is no strong continuity claim on the semigroup. Is this a mistake in the book or are we not able to conclude the strong continuity of the contraction semigroup generated by $(mathcal D(overline A),overline A)$ if $lambdaoperatorname{id}_{mathcal D(A)}-A$ has dense range for some $lambda>0$?
functional-analysis operator-theory semigroup-of-operators
functional-analysis operator-theory semigroup-of-operators
asked Mar 16 at 7:48
0xbadf00d0xbadf00d
1,82641533
1,82641533
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$begingroup$
- If $A$ is a closed dissipative operator, then the range of $lambda-A$ is closed for all $lambda>0$. In fact, if $(lambda x_n-A x_n)$ is Cauchy, then
$$
|x_n-x_m|leq frac 1 lambda|(lambda-A)(x_n-x_m)|.
$$
Hence $(x_n)$ is Cauchy and thus $(Ax_n)$ is Cauchy as well. Since $A$ is closed, $lim_{ntoinfty}x_nin D(A)$ and
$$
lim_{ntoinfty}(lambda-A)x_n=(lambda-A)lim_{ntoinfty} x_nin mathrm{ran}(lambda-A).
$$
- If a contraction semigroup has a densely defined generator, then it is strongly continuous. This result is also somewhere in the book of Engel an Nagel, but the argument is quite simple: Trajectories starting in the domain of the generator are clearly continuous, and the uniform bound $|T_t|leq 1$ allows one to extend this continuity to all trajectories starting in the closure of the domain of the generator.
$endgroup$
add a comment |
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1 Answer
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1 Answer
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$begingroup$
- If $A$ is a closed dissipative operator, then the range of $lambda-A$ is closed for all $lambda>0$. In fact, if $(lambda x_n-A x_n)$ is Cauchy, then
$$
|x_n-x_m|leq frac 1 lambda|(lambda-A)(x_n-x_m)|.
$$
Hence $(x_n)$ is Cauchy and thus $(Ax_n)$ is Cauchy as well. Since $A$ is closed, $lim_{ntoinfty}x_nin D(A)$ and
$$
lim_{ntoinfty}(lambda-A)x_n=(lambda-A)lim_{ntoinfty} x_nin mathrm{ran}(lambda-A).
$$
- If a contraction semigroup has a densely defined generator, then it is strongly continuous. This result is also somewhere in the book of Engel an Nagel, but the argument is quite simple: Trajectories starting in the domain of the generator are clearly continuous, and the uniform bound $|T_t|leq 1$ allows one to extend this continuity to all trajectories starting in the closure of the domain of the generator.
$endgroup$
add a comment |
$begingroup$
- If $A$ is a closed dissipative operator, then the range of $lambda-A$ is closed for all $lambda>0$. In fact, if $(lambda x_n-A x_n)$ is Cauchy, then
$$
|x_n-x_m|leq frac 1 lambda|(lambda-A)(x_n-x_m)|.
$$
Hence $(x_n)$ is Cauchy and thus $(Ax_n)$ is Cauchy as well. Since $A$ is closed, $lim_{ntoinfty}x_nin D(A)$ and
$$
lim_{ntoinfty}(lambda-A)x_n=(lambda-A)lim_{ntoinfty} x_nin mathrm{ran}(lambda-A).
$$
- If a contraction semigroup has a densely defined generator, then it is strongly continuous. This result is also somewhere in the book of Engel an Nagel, but the argument is quite simple: Trajectories starting in the domain of the generator are clearly continuous, and the uniform bound $|T_t|leq 1$ allows one to extend this continuity to all trajectories starting in the closure of the domain of the generator.
$endgroup$
add a comment |
$begingroup$
- If $A$ is a closed dissipative operator, then the range of $lambda-A$ is closed for all $lambda>0$. In fact, if $(lambda x_n-A x_n)$ is Cauchy, then
$$
|x_n-x_m|leq frac 1 lambda|(lambda-A)(x_n-x_m)|.
$$
Hence $(x_n)$ is Cauchy and thus $(Ax_n)$ is Cauchy as well. Since $A$ is closed, $lim_{ntoinfty}x_nin D(A)$ and
$$
lim_{ntoinfty}(lambda-A)x_n=(lambda-A)lim_{ntoinfty} x_nin mathrm{ran}(lambda-A).
$$
- If a contraction semigroup has a densely defined generator, then it is strongly continuous. This result is also somewhere in the book of Engel an Nagel, but the argument is quite simple: Trajectories starting in the domain of the generator are clearly continuous, and the uniform bound $|T_t|leq 1$ allows one to extend this continuity to all trajectories starting in the closure of the domain of the generator.
$endgroup$
- If $A$ is a closed dissipative operator, then the range of $lambda-A$ is closed for all $lambda>0$. In fact, if $(lambda x_n-A x_n)$ is Cauchy, then
$$
|x_n-x_m|leq frac 1 lambda|(lambda-A)(x_n-x_m)|.
$$
Hence $(x_n)$ is Cauchy and thus $(Ax_n)$ is Cauchy as well. Since $A$ is closed, $lim_{ntoinfty}x_nin D(A)$ and
$$
lim_{ntoinfty}(lambda-A)x_n=(lambda-A)lim_{ntoinfty} x_nin mathrm{ran}(lambda-A).
$$
- If a contraction semigroup has a densely defined generator, then it is strongly continuous. This result is also somewhere in the book of Engel an Nagel, but the argument is quite simple: Trajectories starting in the domain of the generator are clearly continuous, and the uniform bound $|T_t|leq 1$ allows one to extend this continuity to all trajectories starting in the closure of the domain of the generator.
answered Mar 16 at 12:20
MaoWaoMaoWao
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3,933618
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