Hilber space and linear bounded operator

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Homework Help Overview

The discussion revolves around the properties of linear bounded operators in the context of Hilbert spaces. The original poster seeks to express a linear bounded operator A as the sum of two operators B and C, where B is self-adjoint and C is skew-adjoint.

Discussion Character

  • Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants explore the definitions of self-adjoint and skew-adjoint operators, with some suggesting expressions involving A that could lead to identifying B and C. There is a focus on deriving expressions for B and C based on the properties of A.

Discussion Status

Some participants have offered hints regarding the relationships between A, A*, and the proposed operators B and C. However, there is a lack of consensus on the definitions and the implications of these expressions, leading to further questioning and exploration of the problem.

Contextual Notes

There is a noted concern regarding the requirement that B and C must also be linear bounded operators, which adds complexity to the discussion about their definitions and the validity of the proposed expressions.

braindead101
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Let H be a Hilbert space and A: H-> H be a Linear Bounded Operator. Show that A can be written as A=B+C where B and C are Linear Bounded Operators and B is self-adjoint and C is skew.

This is suppose to be an easy question but I'm not sure where to start.
I know that self-adjoint is (B*=B) and skew is (C*=-C) but can someone show this?
 
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Hint: A+A* is self-adjoint. Can you find a similar expression that's skew? Then what?
 
A-A* is skew
so A = B+B* + C-C*?
 
What are B and C?
 
braindead101 said:
A-A* is skew
so A = B+B* + C-C*?


Okay, you know that A+ A* is self-adjoint and that A- A* is skew. Your second sentence is non-sense because you have not defined B and C. A is the only operator you have! Your answer must be entirely in terms of A.
 
ohh, so B can be rewritten as A+A*, and C can be rewritten as A-A*?
 
in the question, doesn't it say that B and C are linear bounded operators? i thought this meant i could write the whole B+B* thing
 

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