[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [gnugo-devel] Uncertain defense certainly bad

From: SP LEE
Subject: Re: [gnugo-devel] Uncertain defense certainly bad
Date: Tue, 01 Jul 2003 21:34:37 -0700

At the end of this message is a game where an uncertain owl defense is
certainly bad.

At move 104, GNU Go 3.3.22 plays a terrible move at R11.
Not only is this worth -1 point with gote but it actually hurts
W's eyeshape. After this move, a full eye becomes a half eye.

The move is contributed by the pattern:

Pattern D123
# tm New Pattern (3.1.17)
# tm Modified (3.1.18)

??*??   expand eye shape, not in corner


One possibility here is to make this pattern more
specific. Consider:

??*??   expand eye shape, not in corner

Assuming the X stones are not dead, the move at * does
not contribute a half eye on the edge. The pattern
could be split as follows:

Pattern D123a

??*??   expand eye shape, not in corner


Pattern D123b

??*??   expand eye shape, not in corner


??*??   expand eye shape, not in corner

; attack(A)

This helps a little in the present situation. W still makes a small
defensive move but at least it is not a harmful one.


I have removed this pattern and have run all the regression tests. The result:

./ . owl.tst
4 unexpected FAIL: Correct '1 C12', got '1 B14'
80 unexpected PASS!
./ . neurogo.tst
13 unexpected FAIL: Correct '!P7', got 'P7'
./ . lazarus.tst
16 unexpected PASS!
./ . arend.tst
4 unexpected FAIL: Correct 'R14|S15|R17', got 'S16'
./ . nngs3.tst
390 unexpected PASS!
1000 unexpected PASS!
./ . nngs4.tst
470 unexpected PASS!
./ . arend2.tst
50 unexpected FAIL: Correct 'S14', got 'T13'

For owl:4, B14 seems also to be a good move (I even think it's better than C12, which is too passive), because if B answers with C12, W can play C15 and then B has to defend the corner and W can live easily. A possible sequence is W:B14, B:C12, W:C15, B:D15, W:C16.

For neurogo:13, I don't think this pattern can solve the real problem, i.e. don't start a completely nonsense ko.

For arend:4, S16 seems to be a reasonable move too, at least it's not tenuki.

For arend2:50 I have to take more time to check it.

SP Lee

The new MSN 8: smart spam protection and 2 months FREE*

reply via email to

[Prev in Thread] Current Thread [Next in Thread]