Subspace & Span in Rn: Definition & Examples

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Homework Help Overview

The discussion revolves around the concepts of span and subspace in the context of Rn. The original poster questions the relationship between the span of a set of vectors and its classification as a subspace, particularly when the span encompasses all of Rn.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to clarify whether the span of vectors can be considered a subspace, especially in cases where it equals all of Rn. They also explore the implications of dimensionality on the classification of subspaces.

Discussion Status

Some participants affirm that Rn is indeed a subspace of itself, suggesting that the original poster's understanding aligns with established definitions. However, the exploration of definitions and dimensional constraints remains open, with no explicit consensus reached.

Contextual Notes

The discussion includes considerations of definitions and properties of subspaces, particularly in relation to dimensionality and the nature of spans in vector spaces.

nobahar
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Hello!
Just a quick question. Is the following okay?:
The span of a set of vectors corresponds to a subspace in Rn.
But the span of a set of vectors can also be ALL of Rn, does that mean all of Rn can be considered a subspace? Or does it mean the first definition is not entirely correct, and instead a span of a set of vectors can simply be used to identify a subspace, if it exists.
I realize this is a fairly trivial question, but I would like to make sure that I haven't overlooked anything.
Here is an example of what I mean.
The span(v1,v2), where [tex]v_{1} = \left(\begin{array}{cc}1\\0\end{array}\right), v_{2} = \left(\begin{array}{cc}0\\1\end{array}\right)[/tex] is R2. It is also closed under addition and multiplication, and contains the zero vector, so it satisfies the requirements for a subspace; is it a subspace within, say Rn with n>2? I don't think so, because the vector is composed of two components, and I was thinking a subspace would have to be within the confines of these two dimensions.
Any help appreciated, if it is not clear I can try to re-explain what I mean. I am hoping it's more of an issue of definition.
Thanks in advance.
 
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nobahar said:
Hello!
Just a quick question. Is the following okay?:
The span of a set of vectors corresponds to a subspace in Rn.
But the span of a set of vectors can also be ALL of Rn, does that mean all of Rn can be considered a subspace?
Yes, a vector space is a subspace of itself.
 
[itex]\mathbb{R}^n[/itex] is a subspace of itself (you can verify with the definition that it satisfies the properties of a subspace).
 
Thankyou Vela and Rasmhop.
 

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