Messege for Dr Lau: Book update

My writing was different from my talk

I have given many talks, but I realized that writing is a different ball game altogether. Writing is more rigorous. It is also more precise and thorough. You have to check and cross-check all your facts and make sure that facts are treated as sacred. They cannot be twisted out of context, nor there any hidden slant to your writing.

Also, a talk covers less material a book. A talk reinforces meaning, notation, and direction, because a listener cannot pause or review earlier slides. But this is not possible with a book. You can relax some formal English rules to make your slides terser; but you cannot ever afford to do that with your book.
Within reason, you can write imprecisely, incompletely and even incorrectly for your slides. But your editor or publisher will NEVER allow that with a book. That would be simply blasphemy!