
#1
Feb1907, 11:12 AM

P: 140

could someone please explain to me what the tensor product is and why we invented it? most resources just state it without listing a motivation.




#2
Feb1907, 11:32 AM

Emeritus
Sci Advisor
PF Gold
P: 16,101

It is the "best" notion of multiplication for vector spaces or modules. Any other notion of a "product" of vectors can be defined by doing something to the tensor product of the vectors.




#3
Feb2207, 08:48 PM

Sci Advisor
HW Helper
P: 9,421

a product is an operation which is distributive over addition. we call these bilinear operations.
a tensor product is a universal bilinear ooperatioin such that any other biklinear operation is derived from it. i.e. if G,H are two abelian groups, there is a bilinear map GxH>GtensH such that f=or any other bilinear map GXH>L, THERE IS A factorizATION OF THIS MAP via GxH>GtensH>L. another point f view is that the tensor product is a way of making bilinear maps linear. i.e. the factoring map GtensH>L above is actually linear. linearizing things is always considered a way of making them easier to handle. 



#4
Feb2307, 05:58 AM

P: 2,955

The tensor product and its motivationThe tensor product is a way to combine two tensors to obtain another tensor. Suppose A and B are two vectors and A is the tensor product of the two. Then the tensor product is expressed as (Note: The symbol of the tensor product is an x surrounded by a circle. Since I don't have that symbol at my disposal I will use the symbol "@" instead.) C = A@B The meaning of this expression comes from the action of the tensor C on two 1forms, "m" and "n". This is defined as C(m,n) = A@B(m,n) = A(m)B(n) Best wishes Pete 


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