How come computer science books are so relaxed about specifying which set variables/values belong too ?I've read several books on algorithms like CLRS's Introduction to Algorithms, Sedgewick's An Introduction to the Analysis of Algorithms etc.How come these kind of books are so sloppy about telling which set values/variables belong too ?To give some examples:Introducing Big-O notation books don't mention the domain and co-domain of the functions $f(N)$ and $g(N)$. Neither, is it mentioned which set the constant $C$ belongs too. Introducing Generation Functions nothing is said about the values of the sequence $a_0, a_1, \ldots$. In mathematics these are complex numbers, but nothing is said here.       
How come computer science books are so relaxed about specifying which set variables/values belong too?
algorithms;algorithm analysis