Decisive Game

# Analysis of the decisive game Shokidoki - 1/128 Rigan

 Shokidoki played sente, and after its opening move 1. Bb3, Rigan replies with 1... Sc4, a move which I found (in my attempts to construct an opening repertoire) to be slightly inferior, and after some time will lead to an advantage for sente. The problem seems to be that after trading its B for S, sente can use its abundance of generals to establish one on the central square, which is not attacked by the Bc4. As I have not progressed far in building the book yet, and am still focussing only on the strongest lines, this brings Shokidoki out of book. Before the battle over the central square gets well on its way, Rigan plays 5... Bb5, presumably to open the file for its Rook. This causes a marked increase in Shokidoki's evaluation, to around +1, because it allows it to acquire a promoted Bishop (Dragon Horse) that the opponent cannot quickly dispose of. For a number of moves Rigan plays exactly those moves that Shokidoki also indicates in its analysis, until 10... R@c5, where Shokidoki would have preferred S@c5. Initially this causes Shokidoki scores to rise, but the advantage must be illusory, as after playing a few moves of the PV on which this score was based, it seems to evaporate. After 12. Bxd4 Shokidoki recommends recapture by the King, though, while Rigan does it with the Gold. This seems to be a serious error; Shokidoki's score jumps to +3.5, and stays at that level. I have analyze the position after 12... Kxd4 upto 17 ply (which took 80 minutes), but Shogidoki cannot find a way to increase its advantage to more than the +2 it already thinks it has at that stage. Graph of the scores from 5min/move analysis

Then the score stays hovering around +3.5 for some time, even though Rigan deviates from Shokidoki's expected moves in two places (13... B@e3 was expected in stead of B@d3, and 17... B@d1 in stead of Bxb1+). Then Rigan plays 18... B@e5, which seems a fatal serious mistake. Shokidoki's analysis recommends 18... S@c5 to defend against the threat of 19. B@d4, forking K and R. A 17-ply search after this move cannot get the score much higher than +5. Of course that is already all very bad for 1/128 Rigan; scores of 4 or more are usually decisive, and games tend to end quickly after it is reached, while at +3.5 there can still be a lengthy battle.

The played move 18... B@e5 loses outright, however. After 19. B@d4, Bxd4 is forced (the only two other legal check evasions, Kd2 and Ke2 lead to mate in 7 and mate in 8, respectively) and the position after 20. Rxe5 gives a score of -30.72 for gote at 16 ply, meaning he must already be in a situation where he is busy giving up all his material for spite checks, to push the checkmate over the horizon, and that further analysis would show the mate. (But this one already took 183 min...) As sente could force the preceding 3 ply, the score after 18... B@e5 must already be at least as large.

Shokidoki really never considers 18... B@e5 when put to thinking in that position; it give B@d3, at 10 ply (32 sec) switches to Rd5, and at 11 ply (1:30) to Rxc3, which at thinking times that could be achieved during the game keeps the score around +4. When thinking from scratch in the position after 18... B@e5 it sees the continuation B@d4, BxB, RxB immediately at 1 ply + QS, with a score at a steady +5, (which remains at higher depth), so it never considers that a viable alternative.

### Game with annotations by Shokidoki at 5 min/move

```[Event "Edited game"]
[Site "ONTWIKKELLAPTOP"]
[Date "2013.08.18"]
[Round "7"]
[White "Shokidoki"]
[Black "1/128 Rigan"]
[Result "1-0"]
[Variant "shogi"]
[FEN "rbsgk/4p/5/P4/KGSBR[-] w 0 1"]
[SetUp "1"]

{--------------
r b s g k
. . . . p
. . . . .
P . . . .
K G S B R
white to play
--------------}
1. Bb3 Sc4 2. Bxc4 {+0.20/16}
(b3c2 b5a4 c2a4 a5a4 B@b2 B@d4 b1c2 d4b2 c1b2 B@d4 e1c1 d4b2 c2b2 a4b4 B@a3 b4b5 B@a4 b5a5 a4c2)
2... Bxc4 {+0.36/15}
(b5c4 c1c2 B@d4 S@b2 c4a2 b1a2 P@a3 a2b3 a3a2 a1b1 a2a1+ b1c1 a1a2 b2c3 d4c3 c2c3 S@d3 c1d1)
3. Sc2 {+0.16/17}
(c1c2 B@d4 S@b2 a5b5 e1c1 d4b2 b1b2 S@d2 c1b1 d5d4 B@a4 b5d5 b2a3 c4e2 a3b3 e2b5 a4b5+ d5b5 b3b4)
3... B@d4 {-0.24/16}
(B@d4 S@b2 a5b5 e1c1 d4e3 c1d1 b5b2 d1d5+ c4d5 b1b2 e3c1+ G@b1 c1e3 R@b5 S@d3 b5a5+ d3c2 b1c2)
4. S@b2 {-0.04/17}
(S@b2 a5b5 b2c3 d4c3 c2c3 S@d4 B@b2 d4c3 b2c3 S@d4 c3b2 c4d3 b1c1 b5b2 c1b2 B@c3 e1c1 c3b2 a1b2 d5c5)
4... Rc5 {+0.00/16}
(a5b5 e1c1 d4b2 b1b2 S@d2 c1b1 d5d4 B@a4 b5a5 b2a3 d4d5 a4b3)
5. Rd1 {+0.56/17}
(e1c1 d4e3 c1d1 c4e2 d1e1 e2b5 b2c3 b5a4 e1d1 a4c2 b1c2 S@d4 B@b4 d4c3 c2c3 c5b5 d1b1)
5... Bb5 {+0.12/17}
(c4e2 d1d2 e4e3 d2d4 e5d4 B@d2 d4e4 b2c3 d5e5 b1c1 c5d5 a2a3 e2b5 a1a2 b5e2)
6. Rxd4 {+0.88/17}
(d1d4 d5d4 B@b4 c5d5 b4a5+ b5e2 a5d2 e2b5 b2c3 d4e3 d2c1 b5d3 c2d3 d5d3 c1b2 S@d4 c3d4 d3d4 b2d4 e5d4)
6... Gxd4 {-1.08/17}
(d5d4 B@b4 c5d5 b4a5+ b5c4 a5b4 R@b5 b4e1 c4d3 c2d3 d4d3 B@c4 S@d2 e1d2 d3d2 S@c3 b5c5 c4d5+ c5d5)
7. B@b4 {+1.08/17}
(B@b4 c5d5 b4a5+ b5e2 a5d2 R@e3 a2a3 d4d3 c2d3 e2d3 d2c3 S@d4 c3d3 d4d3 B@c3 B@d4 c3d4 d5d4 B@c3 d3c4 c3d4 e5d4)
7... Rd5 {-1.20/17}
(c5d5 b4a5+ b5e2 a5d2 R@e3 b2b3 d5c5 a2a3 e2d3 a3a4 d4c3 c2c3 d3b1+ a1b1 e3c3 G@c2)
8. Ba5+ {+1.44/17}
(b4a5+ b5d3 c2d3 d4d3 a5b4 S@c5 b4b5 c5d4 b5c4 R@c5 c4d3 d4d3 B@c3 c5c3 b2c3 d3d2 c3c4 d5a5)
8... Bd3 {-1.32/17}
(b5d3 c2d3 d4d3 a5b4 S@c5 b4b5 c5d4 b5d3 d4d3 B@c3 B@d4 c3d4 d5d4 b2c3)
9. Sxd3 {+1.60/16}
(c2d3 d4d3 a5b4 S@c5 b4b5 c5d4 b5d3 d4d3 B@c3 B@d4 c3d4 e5d4 G@c3)
9... Gxd3 {-1.60/16}
(d4d3 a5b4 S@c5 b4b5 c5d4 b5d3 d4d3 B@c3 B@d4 c3d4 e5d4 G@c3 d4e5 B@b3)
10. +Bb4 {+1.68/16}
(a5b4 S@c5 b4b5 R@e1 B@b3 d3d4 b3d5+ d4d5 b5d3 e1d1+ d3c3 B@d4 c3c2 d1c2 b1c2 B@d1 R@d2 d4b2 c2b2)
10... R@c5 {-1.52/15}
(S@c5 b4b5 c5d4 b5c4 R@c5 c4d5 e5d5 B@b4 c5b5 R@a5 b5a5 b4a5+ d4c5 a5a4 d5e5 a4b3)
11. B@c3 {+2.64/15}
(B@c3 S@d4 c3d4 e5d4 b4c5 d5c5 R@a4 d4e5 S@c4 c5c4 a4c4 S@d5 R@b5 B@e3 c4b4 d3d4 b5c5+ B@c4 b1c2)
11... S@d4 {-2.08/16}
(S@d4 c3d4 e5d4 b4c5 d5c5 R@a4 d4e3 S@c4 B@c2 c4d3 c2d3 G@c1 d3b1+ c1b1 G@d3 B@b4 c5d5 a4a5+ d5a5 b4a5+)
12. Bxd4 {+1.96/15}
(c3d4 e5d4 b4c5 d5c5 R@a4 d4e3 S@c4 B@c2 c4d3 c2d3 G@c1 d3b1+ c1b1 G@d3 B@b4)
12... Gxd4 {-1.60/15}
(e5d4 S@b3 B@d1 b4e1 d1b3+ b2b3 d4e5 b3b4 c5c4 B@b3 d5d4 b3c4 d4c4 R@a5 S@d5 a5a3+)
13. S@c3 {+3.48/15}
(S@c3 B@e3 c3d4 e5d4 G@e2 d4e5 e2e3 e4e3 B@c3 c5c3 b4c3 S@d4 c3c4 G@d3 c4d5 e5d5 R@b5 d5e4 b5a5+ e3e2)
13... B@d3 {-3.16/16}
(B@e3 c3d4 e3d4 G@c3 d4e3 c3c4 c5c4 b4c4 G@d4 c4b4 S@d3 b2c3 d4c3 b4c3 S@d4 c3b4 e3d2 b4b3 d2e1+ b3d5 e5d5)
14. +Bxc5 {+3.48/16}
(b4c5 d5c5 c3d4 e5d4 R@b4 d4e3 G@c3 c5c3 b2c3 B@e1 c3d4 e3e2 b4b2 G@d2 R@c5 e2d1 b2d2 e1d2+ G@c1 d1e1 c1d2 d3b1+ a1b1 e1d2 c5c1+ d2e2)
14... Rxc5 {-3.48/15}
(d5c5 c3d4 e5d4 R@b4 d4e3 G@c3 c5c3 b2c3 B@e1 c3d4 e3e2 b4b2 G@d2 R@c5 e2d1 b2d2 e1d2+ G@c1 d1e1 c1d2 d3b1+ a1b1)
15. Sxd4 {+3.48/15}
(c3d4 e5d4 R@b4 d4e3 G@c3 c5c3 b2c3 B@e1 c3d4 e3e2 b4b2 G@d2 R@c5 e2d1 b2d2)
15... Kxd4 {-3.92/15}
(e5d4 R@b4 d4e3 G@c3 d3b1+ a1b1 c5c3 b2c3 S@c2 b1c2 G@d3 c2b3 B@d1 b3a3 d3c3 S@d4 e3d3 d4c3 S@a4 a3b2 G@c2 b2a1 c2c3)
16. R@b4 {+3.92/14}
(R@b4 d4e3 G@c3 d3b1+ a1b1 c5c3 b2c3 S@c2 b1c2 G@d3 c2b3 B@d1 b3a3 d3c3 S@d4)
16... Ke3 {-3.28/15}
(d4e3 G@c3 d3b1+ a1b1 c5c3 b2c3 S@c2 b1c2 G@d3 c2b3 B@d1 b3a3 d3c3 B@c1 S@d2 S@d4 e3e2 d4c3 d2c3 b4e4 e2d3 e4e3 d3c2 e3c3 c2c3)
17. G@c3 {+3.84/14}
(G@c3 B@d1 c3d3 e3d3 B@b5 d3e3 b1c1 S@c2 b5c4+ c5c4 b4c4 c2c1+ c4c1 G@c2 c1d1 c2d1)
17... Bxb1+ {-3.68/14}
(B@d1 c3d3 e3d3 B@b5 d3e3 b5c4+ c5c4 b4c4 S@d3 R@d5 G@e5 d5e5+ d3c4 G@d4 c4b3 b2c3)
18. Kxb1 {+3.84/14}
(a1b1 S@d5 B@b5 B@e2 b5a4+ G@c4 b4c4 d5c4 a4c2 R@d1 G@c1 d1c1+)
18... B@e5 {-4.12/13}
(S@d5 B@b5 B@e2 b5a4+ G@c4 b4c4 d5c4 a4c2 R@d1 G@c1)
19. B@d4 {+6.92/14}
(B@d4 e5d4 b4d4 B@a5 B@d2 e3e2 c3c2 c5c2 d2a5+ S@c4 d4e4 e2d3 e4c4 c2c4 S@d2 d3d4 d2c3 c4c3 a5c3 d4e4)
19... Bxd4 {-7.96/15}
(e5d4 b4d4 B@a5 B@d2 e3e2 c3c2 c5c2 d2a5+ S@c4 B@d1 e2e3 b1c2)
20. Rxd4 {+10.72/15}
(b4d4 B@a5 B@d2 e3e2 c3c2 c5c2 d2a5+ S@c4 B@d1 e2e3 b1c2 G@d3 d4d3 c4d3 c2b1 G@c4 b2c3 c4c3 a5c3 R@b5 G@b3)
20... B@b5 {-11.12/13}
(B@b5 B@b4 c5e5 b2c1 S@e1 d4d1 G@e2 d1e1 e2e1 S@d4 e3e2 d4e5+ e1d1 e5e4 d1c1 b1c1)
21. B@b4 {+13.44/14}
(B@b4 c5c3 b4c3 G@c2 b1c2 S@d3 c2b1 G@c2 b1a1 c2c3 b2c3 B@e1 G@c2 e1c3+ c2c3 S@d2 c3d3 b5d3 d4d5+)
21... Re5 {-15.80/14}
(c5c3 b4c3 G@c2 b1c2 S@d3 c2b1 G@c2 b1a1 c2c3 b2c3 B@d2 c3d2 d3d2 R@d5 S@c3 B@e5 c3d4 e5d4+ e3e2 d5b5+)
22. Sc1 {+399.64/17}
(b2c1 S@e1 d4d1 G@e2 d1e1 e2e1 S@d2 e3e2 d2e1 e2e1 c3c2 S@c3 b4c3 e1e2 c2d2 e2e1 G@d1)
22... G@e2 23. Sc2 {+399.72/13 1.4} S@e1 24. Rd3 {+399.92/3} Bxd3 25. Gxd3#
{+399.96/1 0.2}
{white mates} 1-0
```

### Shokidoki's analysis after the alternative 12... Kxd4

Gxd4 or Kxd4?
``` 17	+1.96	2088.5M	80:03.03 b4c5 d5c5 R@d1 B@e2 S@c3 c5c3 b2c3 d4c3 R@a3 S@b3 d1c1 c3d4 a3b3 S@c4 b3a3 B@c3 S@b2 c3b2 b1b2 S@c3 b2b1 d3d2 a3c3 c4c3
16	+2.40	1780.0M	22:06.51 a2a3 B@d1 S@c3 c5c3 b2c3 d3c3 b4c3 d4c3 R@c1 c3d2 c1d1 d2d1 B@b3 d1e2 b3d5+ B@c3 a1a2 S@d3
15	+1.36	919.0M	11:17.68 a2a3 B@d1 S@c3 c5c3 b2c3 d3c3 b4c3 d4c3 R@c1 c3d2 c1d1 d2d1 B@b3 d1e2 b3d5+ B@c3 G@b2 c3b2 a1b2 R@d2 b2a1 d2d5 B@c4 d5d3 c4d3 e2d3
14	+1.40	480.8M	5:48.29  a2a3 B@d1 S@c3 c5c3 b4c3 d3c3 b2c3 d4c3 R@c1 c3d2 c1d1 d2d1 B@b3 d1e2 b3d5+ B@c3 G@b2 c3b2 a1b2 R@d2 b2a1 d2d5 B@c4 d5d3 c4d3 e2d3
13	+2.64	57.9M	0:41.32	 b4c5 d5c5 R@a4 d4e5 S@c4 c5c4 a4c4 S@d5 R@b5 B@e3 c4a4 d3d4 b5c5+ B@d2 b1c2 d2e1+
12	+2.48	23.1M	0:16.37	 b4c5 d5c5 R@a4 d4e5 S@c4 c5c4 a4c4 S@d5 c4c5+ B@e3 c5b4 B@e1 b4b3 e1d2+
11	+2.48	7.7M	0:05.43	 b4c5 d5c5 R@a4 d4e5 S@c4 c5c4 a4c4 S@d5 c4c5+ B@e3 c5b4 B@e1 b4b3 e1d2+
10	+2.72	3.2M	0:02.32	 b4c5 d5c5 R@a4 d4e5 S@c4 c5c4 a4c4 S@d5 c4c5+ B@d1
9	+2.64	1.5M	0:01.07	 b4c5 d5c5 R@a4 d4e5 S@c4 c5c4 a4c4 S@d5 c4c5+ B@d2 R@b3
8	+1.64	714416	0:00.54	 b4c5 d5c5 R@a4 d4e3 S@c4 B@d1 c4d3 e3d3 a4a3 d3d4 b1c1 d1e2+
7	+2.56	329514	0:00.26	 b4c5 d5c5 R@a4 d4e5 S@c4 c5c4 a4c4 B@d1 c4c5+ S@d5
6	+2.00	152935	0:00.12	 S@d2 d3d2 b4d2 S@e3 G@c3 d4e5 d2c2
5	+2.72	60698	0:00.04	 b4b3 d4e5 S@c4 c5c4 b3c4
4	+2.32	13414	0:00.00	 b4c5 d5c5 R@a4 d4e5 S@c4 c5c4 a4c4
3	+3.16	1961	0:00.00	 S@d2 d3e3 d2e3
2	+3.16	646	0:00.00	 S@d2 d3e3 d2e3 e4e3
1	+2.08	60	0:00.00	 a2a3 eval = 1.60 (dif = -26 cor=56)
```

### Shokidoki's analysis after the alternative 18... S@d5

S@d5 or B@e5 to defend against B@d4?
``` 17	+5.04	3813.3M	68:52.50 B@d4 d5d4 b4d4 B@b5 b1c1 B@e1 S@d2 e1d2+ d4d2 G@b1 c1b1 e3d2 G@c1 d2e2 B@b4 c5d5 b4a5+ b5c4
16	+4.80	1079.8M	16:56.85 B@d4 d5d4 b4d4 B@b5 b1c1 B@e1 S@d2 e1d2+ d4d2 G@b1 c1b1 e3d2 B@b4 c5d5 c3c4 d2e3 c4b5 d5d1+ B@c1 e3e2 G@c2 d1c2 b1c2 G@d3 c2b1
15	+4.44	619.7M	8:52.48	 B@d4 d5d4 b4d4 B@b5 b1c1 B@e1 S@d2 e1d2+ d4d2 G@b1 c1b1 e3d2 B@b4 c5d5 c3c2 d2e3 b2c3 e3e2 G@c1 b5a4
14	+4.60	259.9M	3:58.62	 B@b5 B@e2 b5a4+ G@c4 b4c4 d5c4 a4c2 R@e1 G@c1 e1c1+ c2c1 G@d2 c1d2 e3d2 G@c1 d2e1 c3c4 e2d3 S@c2 d3c2 c1c2 c5c4
13	+4.76	82.3M	1:25.95	 B@b5 B@e2 b5e2+ e3e2 B@d3 e2d1 b4b5+ c5c3 b5d5 G@c1 b1a1 B@d2 S@e2 d1e1 d5e4 G@c2 d3c2 c1c2
12	+4.48	32.5M	0:34.32	 B@d4 d5d4 b4d4 B@b5 S@c2 B@e5 c3d3 b5d3 d4d3 e3e2 B@b4
11	+4.08	20.9M	0:21.57	 B@d4 d5d4 b4d4 B@b5 S@c2 B@e5 d4d1 e3e2 b1c1 G@e3 a2a3 e5c3 b2c3
10	+4.60	7.3M	0:07.29	 B@d4 d5d4 b4d4 B@b5 S@c2 B@e5 c3d3 b5d3 d4d3 e3e2 B@a3 c5c2 b1c2 e5b2 a3b2
9	+5.16	2.6M	0:02.60	 B@d4 d5d4 b4d4 B@b5 b1c1 c5c3 b2c3 G@c2 c1c2 G@d3 d4d3 b5d3 c2b2 B@a1 b2b3 a1c3+ b3c3 d3b1+
8	+5.88	681321	0:00.70	 B@d4 d5d4 b4d4 G@d2 S@d1 B@e1 d1d2 e1d2+ G@c2 d2e2
7	+4.64	234342	0:00.25	 B@b5 G@d2 b5a4+ e3e2 b1a1 B@c1 a4b5 c5b5 b4b5+
6	+4.96	88961	0:00.09	 B@b5 G@d2 b1a1 B@c1 b2c1 c5c3
5	+5.00	52301	0:00.04	 B@b5 B@e2 b5a4+ G@a5 a4a5 c5a5
4	+3.92	24671	0:00.01	 B@b5 G@d4 c3d4 d5d4 b5c4+ c5c4 b4c4
3	+3.56	3715	0:00.00	 c3c2 G@c4 b4a4
2	+4.32	844	0:00.00	 c3c2 e3e2
1	+6.52	71	0:00.00	 b1a1 eval = 6.24 (dif = 67 cor=79)
```

### Shokidoki's analysis after the played 20. Rxd4

``` 16	-30.72	2191.9M	183:25.56 G@d2 d4d2 e3d2 B@b4 d2e2 b4c5+ R@d1 G@c1 B@d3 R@c2 d3c2 c3c2 R@e1 B@b5 S@d3 b5d3+ d1d3+ c2d3 e1c1+ b2c1 B@c2 b1c2 G@a4 S@d1 e2e1 d3e4
15	-10.80	1066.0M	18:31.75 B@a5 B@d5 S@e5 d4d3 e3e2 d5b3+ G@e1 c3c4 e2d3 c4c5 R@d1 b3d1 e1d1 R@a3 d3d2 R@c2 d2e1 a3a5+ e5d4
14	-8.68	443.7M	7:33.67	 B@a5 B@d5 S@e5 d4d3 e3e2 d5b3+ G@e1 c3c4 e2d3 c4c5 R@d1 R@c1 d3e2 b3c4 e2e3 c1d1 e1d1
13	-6.84	180.4M	3:04.18	 B@b5 B@b4 c5e5 b4a5+ b5e2 b2c1 S@e1 a5a4 G@c5 d4d1 e2d1+ a4d1 R@b5 B@b3
12	-7.44	73.4M	1:15.50	 B@b5 b1c1 S@e1 B@d2 e1d2+ d4d2 B@e5 S@b4 G@b3 b4c5+ b3c3 b2c3 e5c3 G@c2
11	-5.52	20.7M	0:20.93	 B@b5 B@c1 e3e2 d4d2 e2e1 c3d4 c5c1+ b1c1 G@b1
10	-5.12	9.1M	0:09.21	 B@b5 B@a3 c5e5 b2c1 e3e2 d4d2 e2e1 a3b2 G@d1 d2d1 e1d1 G@d2 d1e1
9	-5.20	3.7M	0:03.71	 B@b5 b1c1 G@e5 d4d1 e3e2 d1d2 e2e1 B@b4 c5d5 d2d5+ e5d5 b4a5+
8	-5.60	1.3M	0:01.32	 B@b5 B@c1 e3e2 d4d2 e2e1 c3d4 c5c1+ b2c1 G@e2 d2b2 b5a4 d4e4 a4d1+ b2b5+
7	-5.24	596255	0:00.65	 B@b5 b1a1 S@c1 B@b4 c1b2+ a1b2 c5c3 b4c3
6	-5.88	248112	0:00.28	 B@b5 b1c1 G@d5 d4d1 d5c4 B@d4 c4d4 d1d4
5	-3.84	44643	0:00.04	 G@d2 d4d2 e3d2 G@c1 d2e1 B@d2 e1e2
4	-5.00	17201	0:00.01	 G@d2 B@d5 S@e5 d5c4+ c5c4 d4c4
3	-4.68	6704	0:00.00	 G@d2 B@d5 S@c2 b1a1
2	-5.36	1385	0:00.00	 e3e2 b1a1
1	-4.88	120	0:00.00	 G@b3 eval = -5.84 (dif = -57 cor=-99)
```