Is the Tensor Product Associative?

In summary, the associativity of tensor product is a property that states the result of repeatedly applying the tensor product to a set of tensors is independent of the order in which the products are carried out. It is closely related to matrix multiplication and holds for tensors of any dimension. However, there are exceptions such as the Kronecker product, which is not associative. The importance of this property in physics and engineering lies in its ability to allow for the consistent and predictable manipulation of tensors, making them crucial in the formulation and solution of physical and engineering problems.
  • #1
huyichen
29
0
It is a well fact that tensor product is associative up to isomorphism, but how should I use Universal property(you know, diagrams that commute) to show that it is true?
 
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  • #2
http://www.math.uga.edu/%7Eroy/845-3.pdf

especially page 31
 
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  • #3
Show that both (U\otimes V)\otimes W and U\otimes (V\otimes W) both satisfy the universal property. By general nonsense they are then isomorphisc.
 

FAQ: Is the Tensor Product Associative?

1. What is the mathematical definition of the associativity of tensor product?

The associativity of tensor product is a property of binary operations on mathematical objects known as tensors. It states that the result of repeatedly applying the tensor product to a set of tensors is independent of the order in which the products are carried out.

2. How is the associativity of tensor product related to matrix multiplication?

The associativity of tensor product is closely related to matrix multiplication. In fact, matrix multiplication can be seen as a special case of tensor product where the tensors involved are matrices. This means that the associativity of tensor product also holds for matrix multiplication.

3. Does the associativity of tensor product hold for tensors of any dimension?

Yes, the associativity of tensor product holds for tensors of any dimension. This means that it is applicable to tensors in two, three, or even higher dimensions. The defining property of tensors is their ability to transform in a particular way under changes of coordinates, and this property is independent of the dimension of the tensor.

4. Can you provide an example of a tensor product that is not associative?

Yes, a tensor product that is not associative is the Kronecker product, which is used in matrix algebra. This product is not associative because it involves the multiplication of matrices, which are not themselves tensors. Therefore, the result of repeatedly applying the Kronecker product to a set of matrices may depend on the order in which the products are carried out.

5. Why is the associativity of tensor product important in physics and engineering?

The associativity of tensor product is important in physics and engineering because it allows for the manipulation of tensors in a consistent and predictable manner. This property is crucial in the formulation and solution of physical and engineering problems that involve tensors, such as in mechanics, electromagnetism, and fluid dynamics. Without the associativity of tensor product, it would be much more difficult to use tensors to describe and analyze physical systems.

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