[gnugo-devel] (no subject)

[bump]

In-reply-to: <address@hidden>
        (message from Portela Fernand on Thu, 21 Nov 2002 23:06:56 +0100)
Subject: Re: [gnugo-devel] Pattern EJ72
References:  <address@hidden>
--text follows this line--

Nando wrote:

> Lately, I've run quite a lot of twogtp matches and I very often noticed
> the (in most of the cases, bad) effect of the above mentioned pattern.
> Because of its J classification, Gnu Go never plays the joseki :
> 
> |.........
> |...X.....
> |.....O...
> |...X....*
> |.....O.X.
> |.........
> |.........
> +---------
> 
> I also saw Gnu Go play that jump in following position :
> 
> |.....*....
> |...X......
> |.....O....
> |...X....O.
> |.....O.X.O
> |..........
> |..........
> +----------
> 
> while there was clearly more urgent moves to play elsewhere on the board.
> 
> Shouldn't we do something about it, either kill it or make it j maybe ?

I propose the following patch which will prevent the second pattern.

If it is to be our policy that O should play the shoulder-hit
as in the first pattern, we need to check very carefully that
GNU plays well when B tries to counterattack, for example
after pushing up and cutting, like this:

|.........
|...X.....
|.....O.O*
|...X...XO
|.....O.X.
|.........
|.........
+---------

That's probably not joseki but dangerous anyway for GNU Go.

In a joseki variation X cuts off the stone on the third line,
giving O thickness and leaving the 3-3 point open. This
is OK if O knows what to expect and how to play. But 
I doubt that GNU can play it correctly without a lot of 
coaching.

Index: patterns/patterns.db
===================================================================
RCS file: /cvsroot/gnugo/gnugo/patterns/patterns.db,v
retrieving revision 1.88
diff -u -r1.88 patterns.db
--- patterns/patterns.db        20 Nov 2002 19:05:00 -0000      1.88
+++ patterns/patterns.db        25 Nov 2002 17:28:36 -0000
@@ -12403,16 +12403,17 @@
 # If the right edge is the fourth line this is
 # not too good because it provokes X to make territory
 # but there is no really good move in this case.
+# db modified (3.3.13)
 
-.....        jump again
-..*..
-....X
-..O..
-....X
-X.O..
-.....
-.....
------
+??.....        jump again
+??..*..
+??....X
+xxx.O..
+xx....X
+x?X.O..
+??.....
+??.....
+-------
 
 :8,J