Re: computer-go: Most simple Go rules

[Dave Dyer <ddyer@xxxxxxxxxxx>]

At 04:56 PM 6/21/01, Heikki Levanto wrote:
>On Thu, Jun 21, 2001 at 03:38:45PM -0700, Dave Dyer wrote about ko:
>> This is not more satisfactory in any absolute sense. It is similar
>> in effect to the standard Ko rule: The player who has to avoid repetition
>> will be forced to make an inferior move.
>
>No, the player has to make move that threatens to do something - that is not
>necessarily inferior. 

As long as the threats are greater than the value of the ko, they'll
be answered and the Ko will continue.  When the biggest threat that
can be made is less than the value of the ko, the best move is to 
continue the Ko.  Since Ko prevents you playing the best move, 
you must make an inferior move.  


>> Unfortunatly, given a sufficiently complex position, programs will still
>> run forever for all practical purposes.  With 3, 4, 5, ... kos active,
>> the number of different orders you can play the various Kos expands
>> exponentially, and it becomes humanly impossible to keep track if
>> a particular position has been reached before. 
>
>The possibilityes may expand exponentially, but the number of positions
>can only expand linearily. There can at most be one new position for every
>move played! 

Not correct.  Consider each ko as a "bit", with the current owner
of the ko making that bit a zero or a one.  If there are N ko's
on the board, there are 2^N positions that can be cycled through
before any move irrelevant to the ko must be played.

---

What we're really discussing here is the virtue and effect of the
super-ko rule on a rational player of the game.  Without super ko,
the ultimate choice is

        "would I rather continue the (super) ko, or would I rather
        win/lose the game on time."

With super ko, the ultimate choice becomes, instead, to make an
inferior move and still try to win, which is the same choice one
faces in ordinary Ko.  The clinker from the viewpoint of play involving
humans is that playing to win on time can still be contemplated, and the
a new possibility exists;  Hoping you fallable human opponent will
forfeit the game by violating the superko rule.