Re: computer-go: using move order information.

[Heikki Levanto <heikki@xxxxxx>]

Ray Tayek <rtayek@xxxxxxxxxxxxxxxxx> wrote:

> maybe, but my teacher says that if a move has only *one*  (rational)
> answer (i.e. save the group in atari), then you should make that move
> last. not sure what this would mean in a program. but it does give your
> opponent more chances to make a non optimal move.


Yes, that makes sense.  I have learned (where, I can not say), that you
should postpone the obvious answer. If your opponent makes a peep that gains
him 5 points, and threates to cut and damage you for 27 points, you should
not rush to answer, but see if you can first gain some points, for example
by making a small 3-point push into his territory that threates to damage
him for 31 points. If he goes through with his cut, you go through with
your push, and you should win. 


Consider:
   ABCDEFGHJKLMN
  +-------------+
  |.............| 1 
  |.............| 2
  |..X..X.o..o..| 3
  |...+.X.o.+...| 4
  |.....X.o.....| 5
  |..XXXX.oooo..| 6
  |......+......| 7
  |..oooo.XXXX..| 8
  |.....o.X.....| 9
  |...+.o.X.+...| 10
  |..o..o.X..X..| 11
  |.............| 12
  |.............| 13
  +-------------+
   ABCDEFGHJKLMN

All corners are obviously alive.  The position is symmetric, so the score
must be quite even (sans komi).
If x pushes at G12, O would like to answer at F12. X can repeat this four
times, and then start pushing again at F13 (O:E13, X:G13, O:E12), and X
repeats the sequence three more times:

   ABCDEFGHJKLMN
  +-------------+
  |......XXO....| 1
  |......XOO....| 2
  |..X..X.o..o..| 3
  |...+.X.o.+...| 4
  |.....X.o...OO| 5
  |..XXXX.ooooOX| 6
  |XX....+....XX| 7
  |XOoooo.XXXX..| 8
  |OO...o.X.....| 9
  |...+.o.X.+...| 10
  |.....o.X..X..| 11
  |....OOX......| 12
  |....OXX......| 13
  +-------------+
   ABCDEFGHJKLMN

Just by making obvious answers, O has only 40 points against X's 58, a
difference of 18 points, and the whole game.  (ok, I admit, X can cover at
G11 in gote, after which O can take the other points in sente, reducing the
difference by 3 points. Still loosing by 15 points!)

So, if you just look at the board, there is no reason to consider the move
order. And if you look at it psychologically, there is even less reason. If
your opponent has played in this corner, that is the are he has most clear
in his mind, If you answer there, you are playing on something he has just
spent time speculating on, and you allow him to "change the subject". If,
instead, you make a move somewhere else, he will have to interrupt his
speculations, and look at a "new" situation, and decide how to answer that.
Meanwhile you can consider the position that was the actual focus of the
game, if you know what he "has to" answer. If you look at a professional
endgame, many moves that have "obvious" answers, get those answers many
moves later...

-- 
Heikki Levanto     LSD Levanto Software Development   heikki@xxxxxxxxxxxxxxxxx
               "In Murphy we Turst"