Do Hilbert Space Isomorphism Map Dense Sets to Dense Sets?

This result is known as the open mapping theorem, which can be found in any introductory text on functional analysis.In summary, the conversation discusses the density of A(X) in K, given that X is a dense set in H and A is a bounded linear operator and an isomorphism. The conclusion is that A(X) must also be dense in K. This result is known as the open mapping theorem and can be found in any introductory text on functional analysis.
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Suppose that H, K are Hilbert spaces, and A : H -> K is a bounded linear operator and an isomorphism.

If X is a dense set in H, then is A(X) a dense set in K?

Any references to texts would also be helpful.
 
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It is true. Suppose, that A(X) is not dense. Then let V be a non-empty open set in K \ A(X). The pullback of V by A is open (A is bounded) and not empty (A is isomorphism), and by definition it is not in X, which contradicts the fact, that X is dense in H.
 
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1. What is a Hilbert Space Isomorphism?

A Hilbert Space Isomorphism is a mathematical concept that refers to a bijective and isometric mapping between two Hilbert spaces. This means that it is a one-to-one correspondence that preserves the distances between points in the spaces, making them structurally equivalent.

2. What are Dense Sets in Hilbert Spaces?

Dense sets in Hilbert spaces are sets of points that are closely packed together and exist in every possible direction within the space. In other words, there are no gaps or holes in the set, and any point in the space can be approximated by points in the dense set.

3. How does a Hilbert Space Isomorphism map dense sets to dense sets?

A Hilbert Space Isomorphism preserves the structure and distances between points in the space, so it also preserves the density of points. This means that a dense set in one Hilbert space will be mapped to a dense set in the other Hilbert space.

4. Why is it important for Hilbert Space Isomorphisms to map dense sets to dense sets?

Hilbert Space Isomorphisms are important because they allow us to study and understand different Hilbert spaces by relating them to each other. By mapping dense sets to dense sets, we can see how the structures and properties of one space are reflected in the other, providing valuable insights and connections between different mathematical concepts.

5. Are there any applications of Hilbert Space Isomorphisms in real-world problems?

Yes, Hilbert Space Isomorphisms have a wide range of applications in different fields such as physics, engineering, and computer science. For example, they are used in quantum mechanics to relate different systems and in signal processing to analyze and manipulate signals. They are also used in machine learning and data analysis to identify patterns and similarities between data sets.

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