Construction Problem 1
ferdi: On a 9x9 board, how many stones does the biggest living group have, when every stone of the group must be necessary for the life of the group?
Or, to say it differently:
First, only Black plays, constructing a living group with as many stones as possible. Then only White plays, as often as he wants, but is not able to kill the black group. But if one stone is removed from the black group before White starts to play, White is able to kill the black group. (As usual, a "group" can consist of more than one string of stones.)