Identifying elements in V(x)W, V,W V.Spaces

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Discussion Overview

The discussion revolves around the identification of elements within the tensor product of vector spaces, specifically addressing the conditions under which two elements can be considered equivalent. Participants explore the complexities involved in determining equivalence beyond standard cases.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions how to determine if two elements, c(a(x)b) and (a(x)b), are in the same equivalence class in the context of tensor products.
  • Another participant highlights the difficulty in identifying when different representatives in a tensor product represent the same element, using the example of Z/(37) and Z/(101).
  • A participant seeks clarification on whether Z/(37) and Z/(101) are considered fields and how the tensor product is defined in that context.
  • One participant acknowledges a misunderstanding regarding the nature of the tensor product, realizing that it pertains to Z-modules rather than vector spaces.
  • Another participant asserts that for vector spaces, the dimension of the tensor product is the product of the dimensions of the individual spaces, suggesting that equivalence can be determined through basis representation.

Areas of Agreement / Disagreement

Participants express differing views on the nature of tensor products, particularly regarding modules versus vector spaces. There is no consensus on the best approach to identify equivalence in tensor products, indicating ongoing debate and exploration of the topic.

Contextual Notes

Participants note the complexity of tensor products, especially in cases involving modules that are not free, which may complicate the identification of equivalent elements.

WWGD
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Hi, everyone:
I have been playing around with tensor products of vector spaces recently.
This question came up:

How can we tell if c(a(x)b)~(a(x)b) , or wether any two general elements
are in the same class, other than in the std. cases like c(a(x)b)~(ca(x)v)~
(a(x)cv) , etc.

Any Ideas?.
Thanks.
 
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this is why tensor products are hard, it is hard to tell when two reporesentatives for elements represent the same element of a tensor product.

as a tiny example, show that every pair of representatives in the tensor product of Z/(37) and Z/(101) represent the same element. e.g. for all pairs of integers (n,m) and (a,b), their tensor products are equal in that group.
 
Thanks, Mathwonk. I hope I am not missing something obvious
here, but I am kind of confused, tho; are you seeing Z/(37) and
Z/(101) as fields?. How do you define the tensor product, then?
 
Sorry for my dumbness here, Mathwonk. I was stuck with the idea of tensoring
vector spaces, and was thinking of both Z/(37) and Z/(101) as vector
spaces over themselves , so that the tensor did not make sense. Then
I thought for a second and realized it is a Z-module tensor.I'll do the exercise--
and review my algebra.
 
the case of vector spaces is trivial. the dimension of VtensW is always the product of their dimensions, and if {vi} and {wj} are bases, then so is {vitenswj}.
so every element can be written in terms of the basis to see if two elements are equivalent. the hard cases are modules that are not free.
 

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