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[gnugo-devel] findcap()

From: Evan Berggren Daniel
Subject: [gnugo-devel] findcap()
Date: Fri, 22 Nov 2002 14:21:22 -0500 (EST)

This patch generalizes findcap3() into findcap(), which works on strings
of 4 liberties now.  Attack4() now calls findcap() after trying other

The motivation for the patch was to fix capture:4.  Before the patch, the
correct move is not considered.  After the patch, it is considered, but
after the sequence b H6, w F6, b F7, w E1, B F2, w H2, the reading is too
deep and the move at J2 is not found.  The test passes with 3 calls to
increase_depths() first.

The result is a small delta (2 PASS, 3 FAIL) with a general improvement,
and a decrease in reading nodes in reading.tst from 97435 to 97293, and in
owl.tst from 31160705 to  30671831, and owl nodes in owl.tst from 22453 to


Evan Daniel

- generalize find_cap3() to strings with more than 3 liberies
- attack4() now uses find_cap() to look for attacking moves.A

The delta:

ld_owl:302 PASS         properly solved
optics:1201 FAIL        improvement
arb:150 FAIL            maybe real
golife:4 FAIL           improved
lazarus:3 PASS          properly solved (?)


This is the same problem attack5 caused.  The tactics code now sees an
attack and a defense for the T13 dragon, however the owl code believes it
is dead.  I suspect a problem with marginal eye vertices, and plan to
investigate further.


Owl no longer finds J5 as an attack move.  However, with depths increased
by 1, it continues passing.  I have not investigated in detail.


I think that gnugo's understanding of the situation has improved; A3 is
now alive, not dead, which is an improvement.  However, the correct move
at H5 is only valued at 6 points, which I believe is too low.

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