Comment by mafuy

I'm not sure if I'm allowed to name the source on this here, but someone very familiar with the top Go program scene explained that there is a fair chance that a perfect game has been played already. This is based on the probability of a mistake per move in relation to the number of games there were played by top programs. Hard to believe at first, but perchance it is true. The problem is, of course, that we don't know which games are perfect.