I think it that case if you went through the whole book like that a judge would argue that you are infringing because you can recover the whole book like that.

I think it that case if you went through the whole book like that a judge would argue that you are infringing because you can recover the whole book like that. But if you went by and grabbed the very first sentence from each chapter that's is sufficiently in the clear. Especially when you are doing something transformative with it. Like for example analysing what makes for an effective opening sentence. With copyright you always get to ugly slippery slope arguments, Tom Scott has a great video on it. But if you cannot extract something the replaces the original work you should be already in the clear. I'm pretty sure Cole's Notes don't need the original author's permission to print and they are arguably a substitute for reading the original work. I've skimmed through entire series by reading the individual episode summaries on Wikipedia. These are in the clear. The fact that a machine speeds up a human process does not change legality.