[gnugo-devel] Opponent follow-up value and group connection

[SP LEE]

During a game with the latest GNUGO, I continuously felt difficult to catch 
up the 9 stone komi until almost the end game. I found 2 problems with 
GNUGO. I'm still trying to figure out if there is any way to improve GNUGO, 
but I'd like to share my findings with you here.

At move 162, I don't know if GNUGO saw the huge follow up value of white M5. 
Anyway M5 is much bigger than S18.

Then at move 166, GNUGO played M6, letting the lower right corner group T7 
dead by white O6, losing about 30 points. It is interesting that the owl 
analysis of T7 is completely correct. It said that T7 is dead if white plays 
O6 and the defend of T7 is possible at O6.

Below is the top moves GNUGO considered:

Top moves:
1. M6  36.76
2. O6  36.11
3. K6  20.57
4. J7  16.84
5. K7  16.84
6. J2  12.05
7. K8  11.77
8. J6  10.14
9. T15 9.98
10. H7  9.70

 M6: owl attack/defend for L6
 M6:   2.83 (followup) - threatens to capture M5
 M6: 11.17 - change in territory
 M6: 3.87 - strategic effect on L8
 M6: 8.17 - strategic effect on N7
 M6:   3.94 - L6 strategic value already counted - A.
 M6: 8.04 - strategic effect on K5
 M6:   2.83 - total followup value, added 0.00 as territorial followup
 M6: 1.42 - added due to followup (2.83) and reverse followup values (0.00)
 M6: 3.35 - shape (shape values +2.00(1) -0.00(0), shape factor 1.102)
 M6: 0.74 - connects strings (connect value 7, shape factor 0.149)
Move generation values M6 to 36.75

 O6: owl attack/defend for T7
 O6: 29.81 - change in territory
 O6: 3.13 - strategic effect on N7
 O6: 2.48 - strategic bonus for T7
 O6:   4.33 - total followup value, added 4.33 as territorial followup
 O6: 2.16 - added due to followup (4.33) and reverse followup values (0.00)
 O6: -1.79 - shape (shape values +0.00(0) -1.00(1), shape factor 0.952)
 O6: 0.31 - connects strings (connect value 3, shape factor 0.061)
Move generation values O6 to 36.10

owl_attack T7
eye space at Q5 of type 202
vital move at P4, score 50 (eye at Q5, value 0011, pessimistic_min 0)
eye space at S4 of type 310
Pattern A1001 found at O6 with value 80
 Trying white O6. Escape = 0. Current stack: W:O6
 eye space at Q5 of type 202
 vital move at P4, score 50 (eye at Q5, value 0011, pessimistic_min 0)
 eye space at S4 of type 310
 Pattern VA8 found at P4 with value 45
   Trying black P4. Escape = 0. Current stack: W:O6 B:P4
   eye space at Q5 of type 101
   eye space at S4 of type 310
   eye space at Q5 of type 101
   eye space at S4 of type 310
Variation -1: DEAD (no defense)
 Pattern D703 found at P4 with value 70
= 1 O6


I would think if a group is dead and worth 30 points, GNUGO must consider it 
seriously.

SP Lee

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