Change the table layout.
Change a few frac{1}{r} into 1/r.

Note that previously to this commit this was not handled
uniformly in the document.
Remove two unnecessary parentheses.
Add an extra "tilde".
Remove a comma.
Cosmetic changes to Defn 6.9.
Replace "(\cdot)" by "(-)".
Replace a comma by "and".
Add parentheses in Remark 6.3.
Replace "denotes" with "is".
Slightly rephrase Example 8.1.