Continuous extension of homomorphism

In summary: T$. $p(x,x^*)$ is a polynomial in $x$ and $x$ conjugate, so just a complex number.In summary, the conversation discusses a homomorphism that maps polynomials in a bounded normal operator $T$ and its adjoint $T^*$ to complex numbers in the spectrum of $T$. The goal is to prove that this map can be continuously extended to the closure of the set of polynomials in $T$ and $T^*$. The topology used in both spaces is the operator norm. The range of the mapping $h$ is composed of expressions of the form $p(x,x^*)$, where $x$ is a
  • #1
Boromir
38
0
Let $T$ be a bounded normal operator and let $x$ be a member of the spectrum. Consider the homomorphism defined on the set of polynomials in $T$ and $T^{*}$ given by $h(p(T,T^*))=p(x,x^*)$ Prove that this map can be continuosly extended to the closure of $P(T,T^*)$
 
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  • #2
Boromir said:
Let $T$ be a bounded normal operator and let $x$ be a member of the spectrum. Consider the homomorphism defined on the set of polynomials in $T$ and $T^{*}$ given by $h(p(T,T^*))=p(x,x^*)$ Prove that this map can be continuosly extended to the closure of $P(T,T^*)$
What have you tried so far? When you use words like "continuously" and "closure", you are implying the existence of a topology in the space B(H) and also in the space of polynomials. How do you define these topologies?
 
  • #3
Opalg said:
What have you tried so far? When you use words like "continuously" and "closure", you are implying the existence of a topology in the space B(H) and also in the space of polynomials. How do you define these topologies?

just the usual one given by the operator norm. I can see that I need to show 2 things, namely that lim$p_{n}(x,x^*)$ exist given that the corresponding sequence in B(H) converges, and that the map is well defined.
 
  • #4
Boromir said:
just the usual one given by the operator norm. I can see that I need to show 2 things, namely that lim$p_{n}(x,x^*)$ exist given that the corresponding sequence in B(H) converges, and that the map is well defined.
Okay, it's the operator norm in B(H). But what norm are you using on the space of polynomials?
 
  • #5
Opalg said:
Okay, it's the operator norm in B(H). But what norm are you using on the space of polynomials?

a polynomial of operators is just an operator so the same norm.
 
  • #6
Boromir said:
a polynomial of operators is just an operator so the same norm.
The range of the mapping $h$ consists of expressions of the form $p(x,x^*)$. What is $x$ supposed to mean there, and what is $p(x,x^*)$? (It's not an operator).
 
  • #7
Opalg said:
The range of the mapping $h$ consists of expressions of the form $p(x,x^*)$. What is $x$ supposed to mean there, and what is $p(x,x^*)$? (It's not an operator).

$x$ is a member of the spectrum of $T$. $p(x,x^*)$ is a polynomial in $x$ and $x$ conjugate, so just a complex number.
 
  • #8
forget it
 

Related to Continuous extension of homomorphism

What is continuous extension of homomorphism?

Continuous extension of homomorphism is a mathematical concept that involves extending a homomorphism, which is a function that preserves algebraic structure, to a larger domain while maintaining its properties.

Why is continuous extension of homomorphism important?

Continuous extension of homomorphism is important because it allows for the application of algebraic concepts and techniques to a wider range of mathematical structures, making it a useful tool in various fields such as topology, functional analysis, and abstract algebra.

What are the requirements for a continuous extension of homomorphism?

A continuous extension of homomorphism must preserve the algebraic operations of the original homomorphism and also maintain continuity, meaning that small changes in the input should result in small changes in the output.

How is continuous extension of homomorphism related to topology?

Continuous extension of homomorphism is closely related to topology because it relies on the concept of continuity, which is a fundamental concept in topology. In fact, continuous extension of homomorphism is often used in topology to prove certain theorems and properties.

Are there any real-world applications of continuous extension of homomorphism?

Yes, continuous extension of homomorphism has various real-world applications, such as in signal processing, image reconstruction, and data analysis. It is also used in physics and engineering to model and analyze continuous systems.

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