[gnugo-devel] Reading patch

[Gunnar Farnebäck]

Time for a refreshing reading patch. This adds the static function
squeeze_moves() in reading.c, which looks for moves to squeeze out
liberties from superstrings. Typical examples are reading:203,204.

- new static function squeeze_moves() in reading.c

The breakage is (computed before the last patches went into CVS):
reading:203     PASS 1 E9 [1 E9]
filllib:35      FAIL A7 [A8|B8]
trevorb:600     FAIL N7 [F2|F3]
trevor:290      PASS G8 [!A9]
nngs4:730       PASS C17 [C17]
seki:206        PASS A1 [A1]
seki:803        FAIL C1 [C2]
seki:811        PASS A1 [A1]
5 PASS
3 FAIL
Total nodes: 1675157568 3156143 13093899 (+0.19% -0.09% -0.16%)

reading:203
Good pass, targeted testcase.

trevor:290
Good pass. Now it's understood that white A9 can tactically be
attacked with ko (previous result 0).

nngs4:730
The difference is whether E17 can be tactically defended. Without the
patch D17 is found as a defense, with the patch no defense is found.
Unclear what's correct.

seki:206
seki:811
Very good. Ko attack is now found on A4. (The two testcases are
similar but by no means identical.)

filllib:35
Accidental. The primary change is that black A5 is understood to no
longer be tactically safe, which is very good.

trevorb:600
With patch a bogus atari-atari defense appears at N7. The only change
in reading is
B:N7 W:N9 B:N11 W:M10 B:H13 W:K13 attack J13 (22)       0 PASS  1 M12
which of course is very good. Why the atari-atari reading makes a
mistake is unclear. 

seki:803
Many changes in reading results:
 1. B:A2 W:C1 B:B3 attack B3 (16)           0 PASS  1 A1
 2. B:C2 W:C1 B:B1 attack A4 (16)           0 PASS  1 A3
 3. W:A3 B:B1 defend A4 (16)                5 C2    5 C1
 4. W:B1 B:B3 W:C2 B:A2 attack A2 (16)      0 PASS  1 D1
 5. B:B1 attack A4 (17)                     0 PASS  1 C1
 6. B:C2 W:C1 B:B3 attack C1 (16)           0 PASS  1 B1
 7. B:C2 W:C1 B:B3 W:A1 attack C1 (16)      0 PASS  1 A2
 8. B:A2 W:C1 attack A4 (16)                0 PASS  1 A3
 9. B:A2 W:C1 B:B3 attack B3 (16)           0 PASS  1 A1
10. W:C1 defend A4 (17)                     5 A2    4 A2
11. W:A3 B:C1 W:C2 defend C3 (16)           5 B1    4 B1
12. W:A3 B:C1 W:C2 B:B1 attack A4 (17)      0 PASS  1 A1
13. W:A3 B:C2 W:C1 B:B1 defend A4 (16)      5 D1    4 D1
14. W:A3 B:B1 defend A4 (16)                5 C2    5 C1
15. W:C2 B:A2 W:D1 B:B1 attack B1 (16)      0 PASS  4 A3
16. B:A2 W:C2 B:B3 W:C1 attack D2 (16)      0 PASS  1 A1

Number 1,3,4,5,8,9,10,11,12,14,15,16 good. Number 2,6,7 bad. 13 bad
but probably not the fault of the patch. Overall an improvement.

/Gunnar