Linear Functionals Inner Product

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Homework Help Overview

The discussion revolves around proving the existence of a nonzero vector in an n-dimensional vector space that satisfies certain conditions related to linear functionals. The problem involves concepts from linear algebra, specifically linear functionals and their relationship to vector spaces.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are exploring the implications of the conditions set by the linear functionals and questioning the reasoning behind using inner products versus applying the functionals directly. There is also a focus on the existence of a nonzero vector that meets the criteria.

Discussion Status

The discussion is ongoing, with participants raising questions about definitions and the approach to the proof. Some guidance has been offered regarding the use of a basis and the dimensionality of the vector space, but no consensus has been reached on the best method to proceed.

Contextual Notes

There is a mention of confusion regarding the notation used, specifically the meaning of X^\perp, and the implications of the dimensionality condition m < n. The original poster expresses uncertainty about the relevance of their reasoning in the context of the proof.

wurth_skidder_23
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Assume that [tex]m<n[/tex] and [tex]l_1,l_2,...,l_m[/tex] are linear functionals on an n-dimensional vector space
[tex]X[/tex].

Prove there exists a nonzero vector [tex]x[/tex] [tex]\epsilon[/tex] [tex]X[/tex] such that [tex]< x,l_j >=0[/tex] for [tex]1 \leq j \leq m[/tex]. What does this say about the solution of systems of linear equations?This implies
[tex]l_j(x)[/tex] [tex]\epsilon[/tex] [tex]X^\bot[/tex] for [tex]1 \leq j \leq m[/tex] or [tex]l_j(x)=0[/tex] for [tex]1 \leq j \leq m[/tex]. Since it is stated in the problem that [tex]l_1,l_2,...,l_m[/tex] are linear functionals on the vector space X, [tex]l_j(x)=0[/tex]. Does this reasoning even help me find the proof? I am stuck.

If you have trouble reading this, it is also at http://nirvana.informatik.uni-halle.de/~thuering/php/latex-online/olatex_33882.pdf
 
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I don't know what [itex]X^\perp[/itex] means, nor why you are taking the inner product rather than just applying the functional to the vector. You'll obviously need to involve n and use n>m, and the easiest way to use this is appeal to the existence of a basis with n elements.
 
so basically I'm trying to prove that for some nonzero [tex]x[/tex], [tex]l_j(x)=0[/tex]?
 
Yea, for some x, for all j.
 

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