> But document does not say Anthropic bought EVERY book it pirated

Yeah, I wouldn't make this exact claim either. For instance it's probably safe to assume that the pirate datasets contain some books that are out of circulation and which Anthropic happened not to get a used copy of.

They did happen to get every book published by any of the lead plaintiffs though, as a point towards them probably having pretty good coverage. And it does seem to have been an attempt to purchase "all" the books for reasonable approximate definitions of "all".

> When you say, "I'm pretty sure we do...", do you mean that pirated books were used, or were they not used?

I'm pretty sure pirated books were not used, but not certain, and I really don't remember when/why I formed that opinion.