I've checked my understanding of set-notation but am I correct in thinking the question says "H' is-a-subset of H", ie, less complex?

To me the most "general" case is having a large, possibly infinite, H where the bulk would be overly complex. So my (wrong) answer assumes that by reducing complexity of the set I'm reducing the chance of over-fitting. So "in general" I'm *reducing* the chance of deterministic noise. Of course after a certain point it will increase again, limited by a flat lined solution.

So why would assuming H is already less complex be more "general" that this? Additionally, pg 124 states over-fitting increases with complexity. I scratch my head to the point of baldness

Btw, I'm enjoying the video lectures immensely. It's like watch a soap opera with twists & turns, plots & sub-plots, and just when the situation seems impossible the magician doffs his top hat and pulls out another white rabbit

I actually giggled at the cross-validation trick