Genericcoder said:
For example this is a specific example of what I am talking about and that was also what my professor presented when he was explaining some stuff about C* algebra those aren't really well defined like it doesn't give what specifically
what is a tensor !
http://www.quantiki.org/wiki/Tensor_product
Thank you, that helps. So you
don't want a book on tensor calculus! Tensor calculus is the name for a discipline that is used a lot in applied mathematics and it is related to your link, but it is not what you want. I was confused because you used this term.
Firstly,
what is a tensor? A tensor on a ##k##-vector space ##V## is just a multilinear map ##V\times ... \times V\rightarrow k##. This is a covariant tensor. A contravariant tensor is a multilinear map ##V^*\times ...\times V^*\rightarrow k##. Then there are also mixed tensors, which are less important for now, they are multilinear maps of the form ##V\times ...\times V\times V^*\times ...\times V^*\rightarrow k##.
The above paragraph is the concrete picture of tensors and is the one used in physics. In mathematics however, we abstract the above picture and we form things called "tensor products of vector spaces". This is what is described in your link. Well, your link is about C*-algebras and Hilbert spaces which are more advanced.
The first thing to do is to understand the "easy" case of tensor products of vector spaces. All other forms of tensor products will build on that.
This is what I would do:
- First, I would take a look at the beautiful book "Linear Algebra Done Wrong", which is freely available here: http://www.math.brown.edu/~treil/papers/LADW/LADW.pdf Try to understand entire chapter 8
- Second, I would get the book "Advanced Linear algebra" by Roman. It has an entire chapter on tensor products of vector spaces (and a lot more good stuff). After reading this, you will know the theory of tensor products in vector spaces.
- You might be interested in tensor products on more general spaces such as modules (if you are not, skip this step). The book "Introduction to Commutative Algebra" by Atiyah and Macdonald does a great job. For the noncommutative case, check out the first two or three chapters of "An introduction to homological algebra" by Rotman.
- You are likely more interested in tensor products of hilbert spaces and C*-algebras. For this, I recommend the second chapter of Kadison & Ringrose "fundamentals of the theory of operator algebras", it is a chapter on Hilbert spaces. Tensor products on C*-algebras are much more subtle. As reference, you cannot find much better than the appendix of "K-Theory and C*-Algebras: A Friendly Approach" by Wegge-Olsen.