This text supplements the textbook we use. The presentation in our text (see above) is of the form Definition-Lemma-Theorem, and it is crystal clear on the subject.
However, the motivation/intuition part is not well covered. This second text contains lots of examples and pretty pictures. It also has the advantage of being free.
Do not pay attention to the terminology
or the technical material covered in the text.
Its presentation is rather focused to a particular (and of limited interest) area of
computer science, with somewhat inappropriate for our purposes technical exposition.
Good, rigorous, and a little more advanced text than what we need here. Also, it seems to be more biased towards communication networks (but with an overall serious technical exposition).
For the Linear Algebra prerequisites we require elementary knowledge with emphasis on proofs. Any text that focuses on proofs (avoid texts that focus on calculations with matrices and linear systems) should do the job. I'd recommend the following one:
From Abstract Algebra we have minimal requirements. Knowing the definitions of field and vector space (over arbitrary fields) is sufficient. For example, you can check the relevant sections/paragraphs from: