I was thinking a little today about komi, perfect play, and solving Go.
We can define a perfect move as a move that doesn’t lose any points (those points being the ones scored at the end of a perfect game following the move), and perfect play as a series of those perfect moves. So, if we imagine a no-komi opening where White is a perfect player and Black is not, we can divide Black’s potential moves into three classes:
- Perfect. Moves that don’t lose any points.
- Mediocre. Moves that lose points but still leave some first-move advantage.
- Drawing-Losing. Moves that lose all the first-move advantage.
Sometimes it is fairly clear what the perfect move is, for instance in a forced joseki line. During much of the opening it’s unclear which move is perfect and which is just mediocre – for instance, playing nirensei vs nirensei and deciding between invading 3-3, approaching a corner, splitting the side, or playing sanrensei.
I think a good measure of strength is how far into a no-komi opening the Black player can go without necessarily playing perfect moves, but without playing a losing move (again presuming that White plays perfectly.)