"he shows that assessing loop programs by their depth of loops is exactly equivalent to Grzegorczyk’s hierarchy. The rate of growth of primitive recursive functions is indeed related to their computational complexity, in fact, they are identical."

"I would have loved to collaborate with him, because he seemed like a smart, nice guy who’d be fun to work with, but yeah, you know, he was already doing other things. He was staying up all night playing Spacewar!”