Heyall, just asking a question out of curiousity.
I'm a mathematics undergraduate, who likes to write quite detailed notes from textbooks as a method of revising. These notes tend to follow roughly the structure of the textbook chapters - with the same definitions, theorems, etc - but often with differing proofs and exposition. I've been told by classmates that these notes are quite useful for them for revision.
Now, I have no intention of ever turning these notes into anything other than notes - I wasn't even sure about keeping them after the exams ended - but thinking about doing so raised questions for me.
When writing a textbook, what precisely constitutes plagiarism?
For example, in an Abstract Algebra textbook, there are only so many ways to cover group theory - as far as I can tell, the only major differences between how several books I've seen cover group theory is in the exposition and superficially in the proofs and definitions.
If a mathematician was annoyed that the only textbook in his/her subfield was notoriously low on detail, and wrote a book that was very similar - with the exception that it were an easier read - would that constitute plagiarism? (If so, that seems a bit restrictive to me.)
It cannot be that textbooks only contain original research, else few textbooks on undergraduate maths could've been written in the last one hundred years.