There are several ways of dealing with the concept of suicide, the situation where a player creates a chain of his own stones without liberties. Some rules disallow suicide altogether, some allow it by removing the chain. Delayed suicide provides a third option. It is in some ways simpler than either of the other options, as it requires no real additional rules, but is the result of the following rules:
- A player may play a stone on any empty intersection (barring ko).
- After a player has placed a stone (or passed), all opposing chains without liberties are removed.
(note that removing the word "opposing" from the second rule leads to the Simultaneous Capture rule)
Black plays . This is allowed, as the intersection was empty. No stones are removed at this point, as there are no opposing chains without liberties.
White plays elsewhere. Now, and the marked stones are removed, as they are now an opposing chain without liberties.
In effect, the removal of the black stones is delayed until white's next move, hence the name delayed suicide.
Note that this rule makes it possible for a chain without liberties to remain on the board briefly.
Delayed suicide can be used strategically in some situations to achieve a different result from that in normal go. One such situation is oshitsubushi:
With rules that disallow suicide, is not allowed and white is unconditionally alive.
With rules that allow suicide, is a ko threat, as it removes the black stones and thuse requires white to play at the 1-1 point to live.
With delayed suicide, seems to kill the group, but white can save it with a (large enough) ko threat.
If white simply plays elsewhere, and the marked stones will be captured, after which black can play at to kill the group.
To prevent this, white can play in a way that requires a response from black (i.e. a ko threat). After black responds to white's ko threat with , white can then play at to live, as the black stones were removed after .
axd: Something bothers me with this rule: if you introduce a rule that has a parameter that can be changed, you open a can of worms because this causes an entire tree of alternative games to appear. In this case, the parameter is 'history': at the end of a move, you have to go back one move, look what was played, and clean up. So why not allow to go 2 moves back, or 3, or more, or just go back as far as a player wants to go... ? Why stick to 1? In other words, a rule must be complete and not allow for improvements or leave room for doubt or questions, otherwise it is not complete and should be rejected. (Slightly OT, a similar situation: why were hoshi chosen as fixed handicap points? There is no clear answer on that, the answer seems to be lost in time, therefore the idea should be rejected.)
Superdave: But you don't have to look at the history. The rule is simply that after you play your stone you remove the opponent's stones that have no liberties.
coiffe: This rule allows for potential collaboration in 3 color/player Go, because you can more effectively double team. It also makes the rules a little easier.
cani:axd, with this rule you remove the enemy stones that after you moved, will have no liberty. Something like this:
Player put his stone. Player check the board for enemy stones without liberty. Player remove those stones.Turn Ends.
Your idea assumes player save what pieces should be removed (under what capture rule?) and then on the next turn (after the other player move) those pieces will be removed.