Linear Transformations and Dual Vectors: Understanding Matrix Representations

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Discussion Overview

The discussion revolves around the relationship between linear transformations, their matrix representations, and dual vectors in the context of vector spaces V and W. Participants explore the implications of taking transposes of matrices and vectors, and the corresponding transformations between dual spaces.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions whether taking the transpose of a matrix representing a linear transformation between vector spaces V and W results in the matrix representation of a transformation from W* to V*.
  • Another participant emphasizes the importance of fixing a basis for the spaces involved and asks if there are bases on W* and V* that validate the initial claim.
  • A participant asserts that given a basis on W, there exists a corresponding basis on W*, prompting further inquiry about what that basis is.
  • One participant proposes that since any vector has a dual vector, the dual basis for W* can be derived from the basis vectors of W.
  • Another participant agrees that fixing a basis for V also determines the basis for V*, suggesting an isomorphism that provides the dual basis for free.

Areas of Agreement / Disagreement

Participants express varying views on the relationship between bases of vector spaces and their duals, with some agreeing on the existence of dual bases while others seek clarification on the conditions under which these relationships hold. The discussion remains unresolved regarding the specifics of these relationships.

Contextual Notes

The discussion does not clarify the assumptions regarding the bases chosen for the vector spaces and their duals, nor does it resolve the implications of these choices on the transformations discussed.

Who May Find This Useful

Readers interested in linear algebra, particularly those studying linear transformations, dual spaces, and the properties of matrix representations in vector spaces.

mhazelm
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It's been so long since I thought about this, I just need to know if this is correct.

If I have the matrix representation of a linear transformation between vector spaces V and W, and I take the transpose of the matrix, am I in essence constructing the matrix representation of a corresponding transformation from W* to V* (where * denotes dual space)?

And if I take the transpose of a row vector in V, can I think of the resulting column vector as an element of V*?

Thanks in advance! :smile:
 
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When we talk about matrices, we are implicitly fixing a basis for the spaces under consideration. So, let's rephrase your question: are there bases on W* and V* that make what you said true?

What do you think?
 
Given a basis on W, there exist a corresponding basis on W*. Do you know what it is?
 
I thought that given any vector, we could always find the vector dual to it... so couldn't we just find the vectors dual to our basis vectors and call that our basis for W*?

I think in fixing the basis for V we fix the basis for V*. Since they're isomorphic, don't we kind of get the basis for V* for "free"?
 
Yes, that's what I just said. Given a basis for V, what is the dual basis?
 

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