What are the rules when copying examples from text books? For example is it allowed and if so how should the textbook be referenced (e.g. included the name and author?). In particular I'm wondering about this question about BAN logic where I took a screen shot from a PDF version of the textbook (which I own) and find it much preferable than retyping everything using Latex.
Part of the problem is it would be very difficult to translate the notation into MathJax/Latex.