Understanding Linear Maps and Exterior Algebras

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Homework Help Overview

The discussion revolves around understanding a linear map defined from the tensor product of a dual space and an exterior algebra to another exterior algebra. The original poster expresses confusion regarding the notation and the implications of the map's definition, particularly how it relates to the dimensionality of the wedge product.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants explore the notation used in the problem, specifically the meaning of "v hat sub s" and its implications for the wedge product's dimensionality. There is an attempt to clarify how the linear map operates and why it results in an (i-1)-form.

Discussion Status

Some participants have provided clarifications regarding the notation and the structure of the problem. The original poster has indicated a better understanding but is still seeking hints for further progress. Multiple approaches to proving the invariance of the map are being discussed, suggesting a productive exploration of the topic.

Contextual Notes

The original poster has not yet attempted a formal solution and is focused on understanding the problem's setup and notation. There is an emphasis on the need for clarity regarding the definitions and properties of the involved mathematical structures.

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Homework Statement


Please, I just am trying to understand the question. I wish to prove it on my own, but the way the question is phrased makes no sense.

So here it is:

Let us define the linear map
[tex]\phi : V^{*} \otimes \bigwedge^{i} V \rightarrow \bigwedge^{i-1} V[/tex]

by the formula

[tex]\ell \otimes v_1 \wedge ... \wedge v_i \mapsto \sum_{s=1}^{i} (-1)^{s-1} \ell (v_s) v_1 \wedge ... \wedge \hat{v_s} \wedge ... \wedge v_s[/tex]

Prove that the map [tex]\phi[/tex] is well defined and does not depend on the choice of basis.

Homework Equations


Well all the usual definition of exterior algebras, and tensor products are needed.

The Attempt at a Solution



As I stated, I haven't started solving yet, I am simply trying to understand the question. I don't see how it goes to wedge i-1. What exactly is v hat sub s? Does that make i wedges?
I don't think this formula is going to i-1 wedges. Please help me to understand what is going on here.

Homework Statement


Homework Equations


The Attempt at a Solution


Homework Statement


Homework Equations


The Attempt at a Solution

 
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What they are trying to notate by v hat sub s, is that the vector v_s is NOT included in the wedge product. All the other v_i's are. That's why it's an i-1 form.
 
Now it makes sense!

Now I just have to solve the problem. Any hints are appreciated.
 
Well there are two main ways to prove something is invariant
1 show it does not change with form
ie
let x and x' be different forms of x
if
f(x)=f(x')
f is invariant

2 provide an invariant definition
ie
define
f(x)
so that the form of x is not a factor

Since you have been provided a noninvariant definition
let Av be a change of basis
you want to show
l(v1)^v2^...^vn=l(Av1)^Av2^...^Avn=det(a)*l(v1)^v2^...^vn
with det(A)=1
 

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