Real Half Point Ko/ Discussion

Robert Pauli: Just don't get it (7/12 :-).

If White starts, it's -1/2, right.

But if Black starts, why continue? Why ? My thinking is that Black took the ko and locally nothing more was left for White, because fighting the ko is hopeless (since Black is komaster). So later, in winter, Black fills it (for free): +1. Not?

Bill: Here on SL I haven't said much about ko evaluation, because it is difficult to understand without thermography, because komaster analysis is not easy to explain in concrete go terms, and because there is more than one approach.

Your question hinges upon the difference between komaster and komonster. A komaster has just enough primary ko threats to win the ko. A komonster can not only win the ko, she can delay winning the ko until the compensation for losing the ko is less than normal. If the term, komonster is not qualified, she has an unlimited number of primary ko threats and can wait until the end of play to win the ko.

In this case, since Black is only komaster, once he has taken the ko the new position has a miai value of 1/3 and is worth only 2/3 points for Black. If Black were komonster, OTOH, it would be worth a full point. . .

Robert Pauli: . . . and I were right again (3/4) - I see. Pretty subtle. How could I have confused "masters" with "monsters" ;-)