Can you rephrase the question? What is e ?

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Discussion Overview

The discussion revolves around the interpretation of the mathematical symbol "e" in the context of matrix theory, specifically regarding whether a certain set of matrices forms a subspace of the space of n x n matrices. The inquiry touches on foundational concepts in linear algebra and set theory.

Discussion Character

  • Conceptual clarification
  • Technical explanation
  • Homework-related

Main Points Raised

  • One participant seeks clarification on the meaning of "e" in the expression {A e Mn,n | AB = BA for a fixed B e Mn,n, expressing confusion about the notation and its implications.
  • Another participant explains that "e" refers to the symbol \in, indicating membership in the set of n x n matrices, and discusses the concept of a set of matrices that commute with a given matrix B.
  • Further clarification is provided on how to read the notation, specifically that x \in y means "x is in y," and introduces other mathematical symbols like \exists and \forall.
  • A participant expresses self-deprecation regarding their understanding of the symbols and concepts discussed.

Areas of Agreement / Disagreement

Participants generally agree on the interpretation of the symbol "e" as \in and the associated concepts of set membership and subspaces, but the initial confusion about the notation indicates a lack of consensus on the participant's understanding.

Contextual Notes

The discussion highlights potential gaps in foundational knowledge regarding set theory and matrix algebra, which may affect the ability to engage with the problem effectively.

Who May Find This Useful

This discussion may be useful for individuals seeking clarification on mathematical notation, particularly in the context of linear algebra and set theory, as well as those looking for insights into common symbols used in mathematics.

pattiecake
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Can you rephrase the question? What is "e"?

Is {A e Mn,n | AB = BA for a fixed B e Mn,n a subspace of Mn,n? (where Mn,n is a matrix M, of dimension n by n)? Not having had a logic class, I have /no idea/ what this is asking...

I'm not even sure what the e is. Its a small capital e - looks like a greek letter. Equivalent to?
 
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It is this symbol : [itex]\in[/itex]. [itex]A \in M_{n,n}[/itex] means that A is in the space of (n x n)-matrices. So, is the set [itex]S_B[/itex] of all (n x n)-matrices that commute with B a subspace of [itex]M_{n,n}[/itex]? You should know of 3 things to test for to determine if it's a subspace (the subspace test) and using the basic axioms of matrix multiplication, you should be able to solve the problem. The symbol [itex]\in[/itex] is a set theoretic one that says that something is an element of a set. It's not really a logic symbol, it's one used in mathematics all the time. Seeing as how you're working with vector spaces, I'm surprised you've never seen it.
 
Yes. Read [itex]x \in y[/itex] as "[itex]x[/itex] is in [itex]y[/itex]" or "[itex]x[/itex] is an element of the set [itex]y[/itex]."

Some other useful symbols are [itex]\exists[/itex] and [itex]\forall[/itex]. Read [itex]\exists[/itex] as "there exists", and [itex]\forall[/itex] as "for any," or "for all."

These symbols are fairly ubiquitous in mathematics (as are many, many others).
 
Last edited:
I'm retArdEd. Thanks! :smile:
 

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