Real Numbers Vector Space: Countability of Basis

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    Basis Countability
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Discussion Overview

The discussion revolves around the countability of the basis of the vector space formed by the real numbers over the field of rational numbers. Participants explore the implications of assuming a countable basis and the relationship between the countability of basis vectors and the span of the vector space.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant expresses confusion about why the basis of the vector space of real numbers over rational numbers is not countable.
  • Another participant questions the implications of assuming a countable basis for this vector space.
  • A participant suggests that the span of a countable set remains countable, implying that the vector space cannot have a countable basis.
  • Another participant elaborates on the relationship between the number of basis vectors and coefficients, arguing that if both were countable, the resulting set of vectors would also be countable, which contradicts the nature of the vector space in question.

Areas of Agreement / Disagreement

Participants do not reach a consensus; there are multiple competing views regarding the countability of the basis and its implications.

Contextual Notes

The discussion includes assumptions about the nature of spans and the properties of countable sets, which remain unresolved. The dependence on definitions of basis and vector space is also a factor.

leon8179
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I know that the set of real numbers over the field of rational numbers is an infinite dimensional vector space. BUT I don't quite understand why the basis of that vector space is not countable. Can someone help me?
 
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Suppose the basis is countable, what can you conclude from this?
 
the span of a countable set is still countable? so R over Q does not have a countable basis, right?
 
If you have n basis vectors and m possible coefficients then you can only make m*n vectors. Since Q is countable, the number of possible coefficients is countable: [itex]\aleph_0[/itex]. If the number of basis vectors were also countable, the number of vectors would have to be [itex]\aleph_0\times \aleph_0= \aleph_0[/itex]: countable.
 

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