Bill Spight's opening exercise with Elf 1 / Solution

Gospel  

As per Leela Zero's Opening Gospel any of the corner reinforcements marked a will do.

A play with threats  

is the human textbook answer. The reason for not playing at a, is that White has a follow-up at which makes a base, and which also has a follow-up at . The reasoning is sound about choosing plays that have good follow-ups that also have good follow-ups. However, I doubt if any of today's top bots give more than a few rollouts.

Not that is an error. It probably loses a few percentage points to any bot's choice of play, but not enough to make it a clear mistake. It's just that the bots do not value the sides as highly as they do the corners.