Are These Sets Vector Spaces?

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Discussion Overview

The discussion revolves around the question of whether certain sets can be classified as vector spaces. The inquiries focus on specific examples, including n-tuples of real numbers and the set of positive real numbers with unconventional operations. The scope includes theoretical aspects of vector spaces and the verification of axioms related to their definitions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant questions the clarity of the first inquiry regarding n-tuples and the operations defined on R^2, suggesting that it does not make sense as posed.
  • Another participant asserts that the set of all n-tuples of real numbers with standard operations on R^n does indeed form a vector space.
  • There is a suggestion that the second question about positive real numbers with operations defined as x+y = x*y and kx = x^2 is reasonable, but it requires checking the axioms of a vector space.
  • Participants emphasize the importance of verifying whether the axioms, such as the distributive law, are satisfied for the proposed operations.
  • A later post introduces a question about whether a specific 2x2 matrix can be considered a vector space, prompting further inquiry into the operations applicable to it.
  • Participants note that there are additional rules beyond the basic checks that need to be considered when determining if a set is a vector space.

Areas of Agreement / Disagreement

Participants generally agree that the verification of vector space axioms is necessary, but there is disagreement on the clarity and validity of the initial questions posed. The discussion remains unresolved regarding the classification of the specific sets mentioned.

Contextual Notes

There are limitations in the clarity of the initial questions, particularly regarding the operations defined on the sets. The discussion highlights the need for precise definitions and assumptions when evaluating vector spaces.

madking153
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hi,i got 2 question about vector spaces :

1. Do the set of all n-tuples of real numbers of the form (x, x1 ,x2...xn) with the standard operation on R^2 are vector spaces?

2.Do the set of all positive real numbers with operations

x+y =x*y and kx=x^2 are vector space?
 
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1 makes no sense. What do "the standard operations of R^2", which are undefined, have to do with the n-tuples of real numbers? R^n is a vector space.

2, just try and verify the axioms, or figure out where they may go wrong.
 
those question is from a book ...
 
And does the book use phrases like "those question"?

Once again: your first question makes no sense. It would make sense if you asked "Does the set of all n-tuples of real numbers of the form (x1 ,x2...xn) with the standard operation on R^n form a vector space?". In that case the anser is obviously "yes". It makes no sense to talk about " real numbers of the form (x1 ,x2...xn) with the standard operation on R^2" because you can't apply the operations on R^2 to R^n.

The second question, "2.Is the set of all positive real numbers with operations
x+y =x*y and kx=x^2 a vector space?" is reasonable. Matt Grimes' point was that it is just a matter of checking the axioms for (or definition of) a vector space.
 
so you are saying that :
the set of all positive real numbers with operations
x+y =x*y and kx=x^2 are vector space?
 
No, we are saying you should check to see if the "axioms" for a vector space are satisfied yourself. In particular, is the "distributive law", k(x+y)= kx+ ky, satisfied?
 
( a 1 ) --- is this 2x2 matrix a vector space ? sorry for asking this coz this is abstract
1 b me
 
Why is it abstract? What are the operations, for instance, what is k*M for some scalar k? Is that in the set? Check the rules, there really is nothing complicated or hidden in this:

to check if S is a vector space over R, say, check the rules: is ks in S when s is in S and k is in R? ie if s satisfies the rules to be in S, does ks? Similarly what about s+t when s and t are in S? is there a zero vector? Just three simple rules to check.
 
there are a few more rules to check too (like the afformentioned distributive property).
 

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