Why is the dimension of the vector space , 0?

Click For Summary

Discussion Overview

The discussion centers on the dimension of the zero vector space, specifically why the dimension of the set containing only the zero vector, denoted as dim[{0}], is considered to be zero. Participants explore definitions, conventions, and the implications of these concepts within linear algebra.

Discussion Character

  • Conceptual clarification
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant questions the explanation given by their professor regarding the zero vector space not having a basis and therefore having dimension zero, seeking further clarification.
  • Another participant suggests that defining the dimension of the zero subspace as zero is a convention that helps maintain the validity of the rank-nullity theorem.
  • Concerns are raised about the consistency of definitions, with one participant asking if the definition of dimension for the zero subspace differs from that of other vector spaces.
  • There is a contention regarding the basis of the zero subspace, with one participant asserting that the empty set serves as its basis, while another argues that the empty set does not span the zero vector.
  • One participant expresses skepticism about the treatment of the empty set as a basis, emphasizing that it is not linearly independent and questioning the validity of arbitrary definitions in such cases.
  • Another participant notes that the linear combination of no terms equals zero, which complicates the discussion about spanning and basis.
  • A participant expresses a desire to seek further clarification from their professor while being cautious about the potential impact on their academic standing.

Areas of Agreement / Disagreement

Participants exhibit disagreement regarding the nature of the basis for the zero subspace and the implications of its dimension. There is no consensus on whether the empty set can be considered a basis or if the definitions of dimension are consistent across different vector spaces.

Contextual Notes

Participants highlight potential limitations in the definitions and assumptions surrounding the concept of dimension, particularly in relation to degenerate cases like the zero vector space.

Dosmascerveza
Messages
23
Reaction score
0
In other words, why is dim[{0}]=0. My math professor explained that since the 0 vector is just a POINT in R2 that the zero subspace doesn't have a basis and therefore has dimension zero. This is not satisfactory.

For example, I know R2 has a dimension 2, P_n has dimension n+1, M_(2,2) has dimension 4. These numbers make sense to me but if the zero subspace contain the zero vector why does it not have a basis?

Can someone explain this concept to me a bit further
 
Physics news on Phys.org
Convention. It makes, among other things, the rank-nullity theorem work.
 
So you say dim[{o}]=0 because you've defined it that way. So the definition of dimension is different for the zero subspace than for every other V space? But how can there be two definitions of dimension be used in the same sense?
 
Dosmascerveza said:
the zero subspace doesn't have a basis and therefore has dimension zero.
That statement is false; are you sure you heard him correctly? The zero subspace does have a basis -- the empty set.
 
I heard him correctly. He made no mention of the empty set. He may have taken some "liberties" to keep it simple for the country-folk.
 
Hurkyl said:
That statement is false; are you sure you heard him correctly? The zero subspace does have a basis -- the empty set.

Isn't the basis supposed to span the vector space? The empty set does not even span the the null-vector.
In any case, {0} can hardly be treated as a basis, because it is not linearly independent! It is common however to treat trivial cases with "arbitrary" definitions to make general rules hold for these cases as well. Compare with the convention 0^0 = 0 in power series.
 
Jarle said:
Isn't the basis supposed to span the vector space? The empty set does not even span the the null-vector.
The linear combination of no terms is equal to zero.

Dosmascerveza said:
I heard him correctly. He made no mention of the empty set. He may have taken some "liberties" to keep it simple for the country-folk.
I guess I don't find that too surprising -- many people seem to vehemently detest dealing with degenerate cases.
 
Well thanks Hurkyl! I will approach him with your assertion and we will go from there. I hope pressing for some deeper answers won't adversely affect my grade.
 

Similar threads

  • · Replies 15 ·
Replies
15
Views
5K
  • · Replies 8 ·
Replies
8
Views
3K
  • · Replies 4 ·
Replies
4
Views
4K
  • · Replies 25 ·
Replies
25
Views
4K
  • · Replies 1 ·
Replies
1
Views
3K
  • · Replies 8 ·
Replies
8
Views
3K
  • · Replies 0 ·
Replies
0
Views
9K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 9 ·
Replies
9
Views
4K
Replies
5
Views
2K