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Subject: Re: Extensions.

Author: Anthony Cozzie

Date: 06:07:42 10/13/03

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On October 13, 2003 at 08:59:00, macaroni wrote:

>I'm sure if i do that, the new version will do dramatically better...but does
>this in fact add so much extra strength? and do I extend +1 on EVERY check?
>maybe I should run a 'fixed node' game, just to see if it's my incheck thats
>slow. Does my pawn extension system seem reasonable?
>thanks

Essentially everyone extends +1 on check (either giving check or moving out of
check).

_every_ check.

Here is Zappa analyzing the position from the Lasker Bishop Sacrifice post.

With Check Extension: Bxh7 in 1.45 seconds, Mate score in 2.3 seconds, solved in
10 seconds.
1. Qc2 g6 2. c4 f6
 = (0.01)	Depth: 4/11	00:00:00.15	50230kN
1. Qh5 g6 2. Qf3 Nc4 3. Bd4 Rxe3 4. Bxc4
 = (0.09)	Depth: 5/13	00:00:00.43	139088kN
1. Bxh7 Kxh7 2. Qh5 Kg8 3. Bxg7 f5 4. Bd4 Qxd4 5. cxd4 Rxe3 6. Qg6 Kh8 7. fxe3
 = (5.39)	Depth: 6/17	00:00:01.45	549222kN
1. Bxh7 Kh8 2. Qh5 Bg4 3. Bxg7 Kxg7 4. Qg5 Kh8 5. Qf6 Kxh7 6. Qh4 Bh5 7. Qxh5
Kg7 8. Rg3 Kf6 9. Qf3
 =   MAT9	Depth: 7/19	00:00:02.28	1049625kN
1. Bxh7 Kh8 2. Qh5 Bg4 3. Bxg7 Kxg7 4. Qg5 Kh8 5. Qf6 Kxh7 6. Qh4 Bh5 7. Qxh5
Kg7 8. Rg3 Kf6 9. Qf3
 =   MAT9	Depth: 8/18	00:00:03.40	1842380kN
1. Bxh7 Kh8 2. Qh5 Bg4 3. Bxg7 Kxg7 4. Qg5 Kh8 5. Qh6 Qxe3 6. Rxe3 Rxe3 7. Bg6
Kg8 8. Qh7
 =   MAT8	Depth: 9/18	00:00:05.75	3622526kN

Without check extension: Bxh7 in 9 seconds, and still no mate score after 20
seconds.

1. Qh5 g6 2. Qf3 Nc4 3. Bd4 Rxe3 4. Bxc4
 = (0.09)	Depth: 6/9	00:00:00.34	142375kN
1. Bd4 Qd6 2. Be5 Qc5
 = (0.00)	Depth: 7/10	00:00:01.28	606191kN
1. Qh5 g6 2. Qh6 Rxe5 3. Rxe5 Qxc3 4. Re7 Be6 5. R1xe6 Qxd3 6. Re5
 = (0.79)	Depth: 8/15	00:00:04.14	2187381kN
1. Bxh7 Kxh7 2. Qh5 Kg8 3. Bxg7 f6 4. Qh8 Kf7 5. Bxf8 Rxe3 6. Qg7 Ke8 7. Rxe3
 = (4.03)	Depth: 9/13	00:00:08.78	4862209kN
1. Bxh7 Kh8 2. Qh5 Bg4 3. Qh4 Bh5 4. Qxh5 Qxe3 5. Rxe3 Nc4 6. Bf5
 = (8.44)	Depth: 10/16	00:00:11.18	6514072kN
1. Bxh7 Kh8 2. Qh5 Bg4 3. Qh4 Qe7 4. Bxg7 Kxg7 5. Qxg4 Kh8 6. Rxe7 Rxe7 7. Rxe7
Kxh7
 = (9.90)	Depth: 11/18	00:00:12.95	7845541kN

So Zappa is 4 times faster at solving this particular position with the check
extension, and that result is really pretty typical.

anthony



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