My hunch is that 90-99% of all Jeopardy questions can be answered with information in Wikipedia/Wiktionary, properly understood. So I'd start with Wikipedia: ~30GB uncompressed full article text. Break it into chunks; canonicalize phrasings to be more declarative, and include synonyms/hypernym/hyponym phrasings (via something like WordNet), so that various 'cluesy' ways of saying things still bring up the same candid…
I'm not certain, but I'd bet Watson was explicitly not allowed to use something like J!Archive as training data. For one, the questions used in the Jeopardy games it played were drawn randomly from previous questions. More importantly, though, learning a stilted, domain specific language model to play Jeopardy isn't anywhere near as challenging, impressive, or worth pursuing than generating something that includes Je…
I've not heard that, and if true, it would have given Jennings and Rutter, both excellent crammers, a knowledge advantage.
Further, human contestants absolutely review the J!Archive before competing, so why wouldn't Watson?
We don't yet know for sure Jeopardy is only one subset of all the impressive things Watson can do. Notably, in the 'Ask Reddit' answers, the Watson team says: "At this point, all Watson can do is play Jeopardy and provide responses in the Jeopardy format."
So it seems like they're trying to claim the accolades for solving a bigger problem, when in fact they've only done well on a very constrained problem.