Not sure I'll fix this in time, but here goes. Tree now searches to depth d for terminal cases, then bubbles up that information. If it's black's turn and it finds a branch that can lead to unconditional life, it will take the first one it finds and ignore the rest. This is not good because it doesn't consider what white is able to do. Suppose white can avoid the condition in one branch but not the other.
Not sure I'll fix this in time, but here goes. Tree now searches to depth d for terminal cases, then bubbles up that information. If it's black's turn and it finds a branch that can lead to unconditional life, it will take the first one it finds and ignore the rest. This is not good because it doesn't consider what white is able to do. Suppose white can avoid the condition in one branch but not the other.