No, I'd argue that they are separate sites, though it is obvious that y combinator is affiliated, and it's linked at the bottom of the index page. Very rarely w

No, I'd argue that they are separate sites, though it is obvious that y combinator is affiliated, and it's linked at the bottom of the index page. Very rarely will users of hacker news want to go to ycombinator.com, so having the link in such a prominent position is a mistake.