Don Dailey you need to teach underpromotion to Komodo!

[pichy]

[d]8/2P5/8/8/8/3r4/2K5/k7 b - - 0 1

This position is lost for Black, but the "best" move here (i.e., the one that lets Black last longest is Rf3, not Rd4.

This is not about lasting longer with the Black pieces, but selecting the correct promotion piece (Rook) when the correct moves with the Black pieces are played in order to finish the game quicker with White.

After Rd4, the position is

[d] 8/2P5/8/8/3r4/8/2K5/k7 w - - 0 1

and White mates in seven, starting with c8(R).

In this position

[d]8/2P5/8/3r4/1K6/8/8/k7 b - - 0 1

the best move is Kb2, not Rd4.

Unless the tablebases are wrong, the "famous Saavedra ending study" must be in error.

Of course if you select Kb2, not Rd42 which is an error and not the best move, then selecting to promote to Queen would be the best choice.


I am not defending black, all that I say is that the tablebase lead to a lost position regardless if it is longer or shorter, and to select a Queen when it promotes to c8 all that you get is stalemate, while selecting the correct move c8=R lead to a quick win for White. Therefore, if the tablebase select to promote to Queen it is only looking to draw for Black, but if you are playing White you will have to chose c8=Rook in order to finish the game quicker.


PS: Plus for this position you are not suppose to use tablebase, since the object is to find out which engine play the correct move with White, NOT Black without Tablebase. We are trying to determine which engine play this ending correctly, and for that you need to let the engine do its own calculation (not by using tablebase)

[BubbaTough]

There are clearly positions where promotion to rook is the best move, but unlike promotion to knight, they do not occur frequently enough in real games to be an elo contributor (or even elo neutral). Of course, supporting it is a very very small elo hit, and my instinct would be to support it if I was commercial engine developer (which I am not ).

-Sam

[zullil]

[d]8/2P5/8/8/8/3r4/2K5/k7 b - - 0 1

This position is lost for Black, but the "best" move here (i.e., the one that lets Black last longest is Rf3, not Rd4.

This is not about lasting longer with the Black pieces, but selecting the correct promotion piece (Rook) when the correct moves with the Black pieces are played in order to finish the game quicker with White.

After Rd4, the position is

[d] 8/2P5/8/8/3r4/8/2K5/k7 w - - 0 1

and White mates in seven, starting with c8(R).

In this position

[d]8/2P5/8/3r4/1K6/8/8/k7 b - - 0 1

the best move is Kb2, not Rd4.

Unless the tablebases are wrong, the "famous Saavedra ending study" must be in error.

Of course if you select Kb2, not Rd42 which is an error and not the best move, then selecting to promote to Queen would be the best choice.


I am not defending black, all that I say is that the tablebase lead to a lost position regardless if it is longer or shorter, and to select a Queen when it promotes to c8 all that you get is stalemate, while selecting the correct move c8=R lead to a quick win for White. Therefore, if the tablebase select to promote to Queen it is only looking to draw for Black, but if you are playing White you will have to chose c8=Rook in order to finish the game quicker.


PS: Plus for this position you are not suppose to use tablebase, since the object is to find out which engine play the correct move with White, NOT Black without Tablebase. We are trying to determine which engine play this ending correctly, and for that you need to let the engine do its own calculation (not by using tablebase)

I'm sorry, but I have no idea what you're trying to say.

[d]8/2P5/8/8/3r4/8/2K5/k7 w - - 0 1

Are there engines that, when denied tablebases, fail to see a quick mate here?

[pichy]

[d]8/2P5/8/8/8/3r4/2K5/k7 b - - 0 1

This position is lost for Black, but the "best" move here (i.e., the one that lets Black last longest is Rf3, not Rd4.

This is not about lasting longer with the Black pieces, but selecting the correct promotion piece (Rook) when the correct moves with the Black pieces are played in order to finish the game quicker with White.

After Rd4, the position is

[d] 8/2P5/8/8/3r4/8/2K5/k7 w - - 0 1

and White mates in seven, starting with c8(R).

In this position

[d]8/2P5/8/3r4/1K6/8/8/k7 b - - 0 1

the best move is Kb2, not Rd4.

Unless the tablebases are wrong, the "famous Saavedra ending study" must be in error.

Of course if you select Kb2, not Rd4 which is an error and not the best move, then selecting to promote to Queen would be the best choice.


I am not defending black, all that I say is that the tablebase lead to a lost position regardless if it is longer or shorter, and to select a Queen when it promotes to c8 all that you get is stalemate, while selecting the correct move c8=R lead to a quick win for White. Therefore, if the tablebase select to promote to Queen it is only looking to draw for Black, but if you are playing White you will have to chose c8=Rook in order to finish the game quicker.


PS: Plus for this position you are not suppose to use tablebase, since the object is to find out which engine play the correct move with White, NOT Black without Tablebase. We are trying to determine which engine play this ending correctly, and for that you need to let the engine do its own calculation (not by using tablebase)

I'm sorry, but I have no idea what you're trying to say.

[d]8/2P5/8/8/3r4/8/2K5/k7 w - - 0 1

Are there engines that, when denied tablebases, fail to see a quick mate here?

In most of the thread in this forum in order to know in detail what was the original topic and message you usually have to read the first thread or posting and sometimes 2nd in order to know what the main point was. I was referring that most engines without tablebase can not find the correct promotion (when the Rook move to Rd4 seeking for the White opponent to make an error by seleccting c8=Queen leading to stalemate) but if those move order change as the one that the tablebase selected such as Kb2 due to introduction of modern tablebase then the sequence of the moves will have to be difference as well by seledting to promote to Queen instead of a Rook.


PS: Anyway here is where the original posting or thread started as you can study Komodo analysis after White Kc3-c2 Rd1-d4 c7-c8Q. Komodo does not select c7 c8= Rook to prevent stalemate :

FEN: 8/8/1KP5/3r4/8/8/8/k7 w - - 0 1

Komodo3-64:
1 00:00 52 520,000 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4
2 00:00 203 203,111 +1.40 c6-c7 Ka1-b2 c7-c8Q
3 00:00 620 206,648 +1.44 c6-c7 Rd5-d2 c7-c8Q Rd2-b2+ Kb6-a5
4 00:00 1,043 260,768 +0.01 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1
5 00:00 1,278 319,523 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q
5 00:00 1,284 256,745 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q
6 00:00 1,629 271,476 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q
6 00:00 1,635 233,572 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q
7 00:00 2,290 254,422 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q
7 00:00 2,296 229,594 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q
8 00:00 3,374 281,142 +0.16 c6-c7
8 00:00 5,199 346,614 +0.63 c6-c7
8 00:00 6,804 378,007 +1.34 c6-c7
8 00:00 17,827 379,290 +1.78 c6-c7 Rd5-d3 c7-c8Q Ka1-b2 Qc8-h8+ Rd3-c3 Kb6-b5 Kb2-c2 Qh8-d4 Rc3-b3+ Kb5-c5
8 00:00 17,835 371,559 +1.78 c6-c7 Rd5-d3 c7-c8Q Ka1-b2 Qc8-h8+ Rd3-c3 Kb6-b5 Kb2-c2 Qh8-d4 Rc3-b3+ Kb5-c5
9 00:00 32,693 510,819 +1.79 c6-c7 Rd5-d3 c7-c8Q Ka1-b2 Qc8-c4 Rd3-c3 Qc4-e2+ Kb2-b3 Qe2-d2 Rc3-c4 Qd2-d1+ Kb3-a3 Qd1-e1 Ka3-b2
9 00:00 32,701 503,088 +1.79 c6-c7 Rd5-d3 c7-c8Q Ka1-b2 Qc8-c4 Rd3-c3 Qc4-e2+ Kb2-b3 Qe2-d2 Rc3-c4 Qd2-d1+ Kb3-a3 Qd1-e1 Ka3-b2
10 00:00 63,316 666,475 +1.81 c6-c7 Rd5-d3 c7-c8Q Ka1-b2 Qc8-c4 Rd3-c3 Qc4-d5 Kb2-a3 Qd5-d4 Ka3-b2 Kb6-a5 Kb2-c2 Qd4-e5
10 00:00 63,324 659,620 +1.81 c6-c7 Rd5-d3 c7-c8Q Ka1-b2 Qc8-c4 Rd3-c3 Qc4-d5 Kb2-a3 Qd5-d4 Ka3-b2 Kb6-a5 Kb2-c2 Qd4-e5
11 00:00 122,183 749,588 +1.84 c6-c7 Rd5-d3 c7-c8Q Ka1-b2 Qc8-e6 Rd3-c3 Kb6-b5 Kb2-a3 Qe6-d6+ Ka3-b2 Qd6-d5 Kb2-a3 Qd5-d4 Rc3-b3+ Kb5-c5
11 00:00 122,191 745,069 +1.84 c6-c7 Rd5-d3 c7-c8Q Ka1-b2 Qc8-e6 Rd3-c3 Kb6-b5 Kb2-a3 Qe6-d6+ Ka3-b2 Qd6-d5 Kb2-a3 Qd5-d4 Rc3-b3+ Kb5-c5
12 00:00 310,610 949,878 +1.89 c6-c7 Rd5-d3 c7-c8Q Ka1-b2 Qc8-h8+ Kb2-b3 Qh8-e5 Rd3-c3 Kb6-b5 Rc3-d3 Qe5-f5 Kb3-c3 Qf5-c5+ Kc3-d2 Qc5-f2+ Kd2-c1 Kb5-b6 Rd3-b3+ Kb6-c5
12 00:00 310,618 947,003 +1.89 c6-c7 Rd5-d3 c7-c8Q Ka1-b2 Qc8-h8+ Kb2-b3 Qh8-e5 Rd3-c3 Kb6-b5 Rc3-d3 Qe5-f5 Kb3-c3 Qf5-c5+ Kc3-d2 Qc5-f2+ Kd2-c1 Kb5-b6 Rd3-b3+ Kb6-c5
13 00:00 375,703 973,324 +1.89 c6-c7 Rd5-d3 c7-c8Q Ka1-b2 Qc8-h8+ Kb2-b3 Qh8-e5 Rd3-c3 Kb6-b5 Rc3-d3 Qe5-f5 Kb3-c3 Qf5-c5+ Kc3-d2 Qc5-f2+ Kd2-c1 Qf2-f4+ Rd3-d2 Qf4-c4+ Rd2-c2 Qc4-d4
13 00:00 375,711 970,826 +1.89 c6-c7 Rd5-d3 c7-c8Q Ka1-b2 Qc8-h8+ Kb2-b3 Qh8-e5 Rd3-c3 Kb6-b5 Rc3-d3 Qe5-f5 Kb3-c3 Qf5-c5+ Kc3-d2 Qc5-f2+ Kd2-c1 Qf2-f4+ Rd3-d2 Qf4-c4+ Rd2-c2 Qc4-d4
14 00:00 696,868 1,035,464 +1.73 c6-c7 Rd5-d6+
14 00:00 700,879 1,036,802 +1.26 c6-c7 Rd5-d6+
14 00:00 704,063 1,035,386 +0.55 c6-c7 Rd5-d6+
14 00:00 715,763 1,037,336 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
14 00:00 715,771 1,037,348 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
15 00:00 729,837 1,039,654 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
15 00:00 729,845 1,039,665 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
16 00:00 756,853 1,046,823 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
16 00:00 756,861 1,045,386 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
17 00:00 790,306 1,060,812 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
17 00:00 790,314 1,059,401 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
18 00:00 837,605 1,076,613 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
18 00:00 837,613 1,075,239 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
19 00:00 903,764 1,102,151 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
19 00:00 903,772 1,100,817 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
20 00:00 1,017,902 1,137,320 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
20 00:00 1,017,910 1,137,329 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
21 00:01 1,163,781 1,180,305 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
21 00:01 1,163,789 1,179,118 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
22 00:01 1,395,637 1,233,984 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
22 00:01 1,395,645 1,233,991 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
23 00:01 1,719,305 1,292,710 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
23 00:01 1,719,313 1,291,745 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
24 00:01 2,177,298 1,339,052 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
24 00:01 2,177,306 1,338,232 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
25 00:02 2,906,827 1,394,830 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
25 00:02 2,906,835 1,394,164 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
26 00:02 4,088,550 1,453,965 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
26 00:02 4,088,558 1,453,451 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
27 00:04 7,522,955 1,527,193 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
27 00:04 7,522,963 1,526,885 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
28 00:08 12,686,734 1,573,060 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
28 00:08 12,686,742 1,572,866 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
29 00:15 24,621,324 1,616,845 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
29 00:15 24,621,332 1,616,739 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
30 00:32 55,173,795 1,684,130 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
30 00:32 55,173,803 1,684,130 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
31 00:54 91,575,585 1,677,823 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
31 00:54 91,575,593 1,677,792 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
32 02:37 271,414,833 1,723,651 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
32 02:37 271,414,841 1,723,640 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
33 07:23 778,049,905 1,753,849 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
33 07:23 778,067,178 1,753,829 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4 Stalemate

[pichy]

[d]8/2P5/8/8/8/3r4/2K5/k7 b - - 0 1

This position is lost for Black, but the "best" move here (i.e., the one that lets Black last longest is Rf3, not Rd4.

This is not about lasting longer with the Black pieces, but selecting the correct promotion piece (Rook) when the correct moves with the Black pieces are played in order to finish the game quicker with White.

After Rd4, the position is

[d] 8/2P5/8/8/3r4/8/2K5/k7 w - - 0 1

and White mates in seven, starting with c8(R).

In this position

[d]8/2P5/8/3r4/1K6/8/8/k7 b - - 0 1

the best move is Kb2, not Rd4.

Unless the tablebases are wrong, the "famous Saavedra ending study" must be in error.

Of course if you select Kb2, not Rd42 which is an error and not the best move, then selecting to promote to Queen would be the best choice.

I'm sorry, but I have no idea what you're trying to say.

Another way of looking at this is that in the time of Saavedra in 1895 when the majority of the GMs thought that the original position was a dead draw since after Black played the text move Rd4 instead of Bb2 in order to trick the opponent if he selected the normal move c7-c8=Queen then Rc3+ forcing the Queen to exchange and stalemate as most top engine still select today without the use of tablebase ( Houdini, critter, Spike, Komodo,Spark, Spike) but Saavedra saw that if you underpromote to Rook White can take the Black Rook and still win.



Please watch the video and see why GMs in the era of Saavedra selected Rd4 hoping to trick their opponents and not Kb2.


[d]8/2P5/8/8/3r4/8/2K5/k7 w - - 0 1

Are there engines that, when denied tablebases, fail to see a quick mate here?

Yes most top engines still do without the use of tablebase

[zullil]

[d]8/2P5/8/8/3r4/8/2K5/k7 w - - 0 1

Are there engines that, when denied tablebases, fail to see a quick mate here?

Yes most top engines still do without the use of tablebase

Please give an example of a top engine that does not find mate-in-7 for the diagrammed position. Every top engine I have tried solves the position very quickly without tablebases.

For example:

Code: Select all

Critter v1.4 64-bit SSE4, by Richard Vida
setoption name Tablebase Usage value Disable
setboard 8/2P5/8/8/3r4/8/2K5/k7 w - - 0 1
info string Opening book: "book.cbk" - 57853 entries [native]
info string GTB Init OK (5 piece set)
info string Using 8 thread(s), 2048 MB hash
go infinite
 2/ 4  00:00       162       0  +0.14 c8=R Ra4 Rb8
 2/ 4  00:00       309       0  +3.48 Kc3 Rd7 c8=Q
 3/ 4  00:00       718  718000  +3.51 Kc3 Ra4 c8=Q Ra3+ Kb4 Kb2 Qh8+ Ka2
 4/ 6  00:00       801  801000  +3.51 Kc3 Ra4 c8=Q Ra3+ Kb4 Kb2 Qh8+ Ka2
 5/ 7  00:00      1242 1242000  +0.00 Kc3 Rd1 Kc2 Rd4
 5/ 8  00:00      2121 2121000  +6.44 c8=R Rd2+ Kxd2 Kb2 Rc3 Ka2 Kc2
 6/10  00:00      2718 1359000  +6.37 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4
 7/10  00:00      3256 1628000  +6.47 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4 Kb1 Ka4
 8/10  00:00      3671 1835500  +6.44 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4 Kb1 Kc3 Kc1
 9/14  00:00      5577 1394250  +6.55 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4 Ka2 Rc2+ Ka1 Kb3 Kb1 Kc3 Ka1
10/16+ 00:00      7418 1483600  +6.95 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4 Ka2 Rc2+ Ka1 Kb3 Kb1 Rc3
10/16+ 00:00      7623 1270500  +7.36 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4 Ka2 Rc2+ Ka1 Kb3 Kb1 Rc3
10/16+ 00:00      7884 1126285  +7.97 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4 Ka2 Rc2+ Ka1 Kb3 Kb1 Rc3
10/16+ 00:00      8101 1012625  +8.88 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4 Ka2 Rc2+ Ka1 Kb3 Kb1 Rc3
10/16+ 00:00      8286  920666 +10.25 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4 Ka2 Rc2+ Ka1 Kb3 Kb1 Rc3
10/16+ 00:00      8499  944333 +12.31 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4 Ka2 Rc2+ Ka1 Kb3 Kb1 Rc3
10/16+ 00:00      8681  868100 +15.39 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4 Ka2 Rc2+ Ka1 Kb3 Kb1 Rc3
10/16+ 00:00      8855  805000 +20.01 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4 Ka2 Rc2+ Ka1 Kb3 Kb1 Rc3
10/16  00:00     10717  824384    +M8 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Rc6 Ka2 Rc2+ Ka1 Kb3 Kb1 Rc3 Ka1 Rc1#
11/16  00:00     11511  822214    +M8 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4 Ka2 Rc2+ Ka1 Kb3 Kb1 Rc3 Ka1 Rc1#
12/16  00:00     12460  778750    +M8 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4 Ka2 Rc2+ Ka1 Kb3 Kb1 Rc3 Ka1 Rc1#
13/16  00:00     13748  723578    +M8 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4 Ka2 Rc2+ Ka1 Kb3 Kb1 Rc3 Ka1 Rc1#
14/16  00:00     15281  727666    +M8 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4 Ka2 Rc2+ Ka1 Kb3 Kb1 Rc3 Ka1 Rc1#
15/16  00:00     18052  752166    +M8 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4 Ka2 Rc2+ Ka1 Kb3 Kb1 Rc3 Ka1 Rc1#
16/16  00:00     25988  866266    +M8 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Ka4 Ka2 Rc2+ Ka1 Kb3 Kb1 Rc3 Ka1 Rc1#
17/17  00:00     33244  949828    +M8 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Ka4 Ka2 Rc2+ Ka1 Kb3 Kb1 Rc3 Ka1 Rc1#
18/17  00:00     49222 1144697    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
19/17  00:00     59017 1180340    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
20/17  00:00     79051 1317516    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
21/17  00:00     98760 1390985    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
22/17  00:00    122724 1515111    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
23/17  00:00    161673 1666731    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
24/19  00:00    210858 1802205    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
25/19  00:00    280505 1961573    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
26/21  00:00    383137 2164615    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
27/21  00:00    579169 2518126    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
28/21  00:00    726296 2584683    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
29/21  00:00    935992 2674262    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
30/21  00:00   1206184 2818186    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
31/21  00:00   1520008 2917481    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
32/21  00:00   1929155 3052460    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
33/21  00:00   2374658 3166210    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
34/23  00:00   2920565 3288924    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
35/23  00:01   3550163 3400539    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
36/23  00:01   4308042 3554490    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
37/23  00:01   5129644 3630321    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
38/23  00:01   6138778 3780035    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
39/25  00:01   7363444 3920896    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
?40/25  00:02   8774903 4077557    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
41/25  00:02  10268638 4227516    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#

bestmove c8=R ponder Ra4

time: 2689 nodes: 11531236 evals: 5055001 knps: 4288
phash: 75.86% evalcache: 0.49% lazy: 99.95% eg_recog: 2688801
splits: 41731

Code: Select all

Crafty v23.4 (8 cpus)

White(1): egtb off
White(1): setboard 8/2P5/8/8/3r4/8/2K5/k7 w - - 0 1
White(1): st 15
search time set to 15.00.
White(1): go
              time limit 15.00 (+0.00) (15.00)
              depth   time  score   variation (1)
starting thread 1 2 3 4 5 6 7 <done>
               15->   0.06  Mat08   1. c8=R Ra4 2. Kb3 Kb1 3. Kxa4 Kb2
                                    4. Rc7 Ka2 5. Rc2+ Ka1 6. Kb3 Kb1 7.
                                    Rc8 Ka1 8. Rc1# (s=2)
              time=0.06  mat=-4  n=170817  fh=91%  nps=1.0M
              extensions=11K qchecks=12K reduced=25K pruned=86K
              predicted=0  evals=10K  50move=0  EGTBprobes=0  hits=0
              SMP->  splits=15  aborts=0  data=7/512  elap=0.06
terminating SMP processes.

mate in 8 moves.

White(1): c8=R
              time used:   0.06

Code: Select all

spark-1.0
(c) 2009-2010 AJ Siemelink

inifile=spark.ini

book=spark.bbk, 4651 moves
book.file=spark.bbk
allocating hash...allocated 32Mb
starting threads...started 16 threads

initialized
% uci

id name spark-1.0
id author AJ Siemelink
option name UCI_EngineAbout type string default spark-1.0 by AJ Siemelink
option name UCI_Opponent    type string
option name UCI_AnalyseMode type check default false
option name Threads         type spin   default 16 min 1 max 16
option name Hash            type spin   default 32 min 1 max 4096
option name Ponder          type check  default true
option name MultiPV         type spin   default 1 min 1 max 256
option name MultiPVMargin   type spin   default 100 min 0 max 2000
option name OwnBook         type check  default true
option name eval.mobility.opening      type spin default 100 min 0 max 1000
option name eval.mobility.endgame      type spin default 100 min 0 max 1000
option name eval.passedpawns.opening   type spin default 100 min 0 max 1000
option name eval.passedpawns.endgame   type spin default 100 min 0 max 1000
option name eval.pawnstructure.opening type spin default 100 min 0 max 1000
option name eval.pawnstructure.endgame type spin default 100 min 0 max 1000
option name eval.kingattack            type spin default 100 min 0 max 1000
uciok
setoption name Threads value 8
setoption name Hash value 1024
position fen 8/2P5/8/8/3r4/8/2K5/k7 w - - 0 1
go infinite
info depth 1 currmovenumber 1 currmove c7c8Q time 0 nodes 0 hashfull 0
info depth 1 seldepth 0 score cp 0 time 1 nodes 71 hashfull 0 pv c7c8Q d4c4 c8c4
info depth 1 seldepth 0 score cp 1 time 1 nodes 95 hashfull 0 pv c7c8R d4a4
info depth 1 seldepth 0 score cp 640 time 1 nodes 211 hashfull 0 pv c2c3 d4d1 c7c8Q
info depth 2 currmovenumber 1 currmove c2c3 time 1 nodes 211 hashfull 0
info depth 2 seldepth 1 score cp -150 time 1 nodes 245 hashfull 0 pv c2c3 d4d1
info depth 2 seldepth 1 score cp 0 time 1 nodes 278 hashfull 0 pv c7c8Q d4c4 c8c4
info depth 2 seldepth 1 score cp 640 time 1 nodes 434 hashfull 0 pv c2b3 a1b1 c7c8Q
info depth 3 currmovenumber 1 currmove c2b3 time 1 nodes 443 hashfull 0
info depth 3 seldepth 2 score cp 640 time 1 nodes 468 hashfull 0 pv c2b3 a1b1 c7c8Q
info depth 3 seldepth 4 score cp 733 time 1 nodes 619 hashfull 0 pv c7c8R d4a4 c2b3 a1b1 b3a4
info depth 4 currmovenumber 1 currmove c7c8R time 1 nodes 622 hashfull 0
info depth 4 seldepth 4 score cp 733 time 1 nodes 674 hashfull 0 pv c7c8R d4a4 c2b3 a1b1 b3a4
info depth 5 currmovenumber 1 currmove c7c8R time 1 nodes 706 hashfull 0
info depth 5 seldepth 4 score cp 733 time 1 nodes 931 hashfull 0 pv c7c8R d4a4 c2b3 a1b1 b3a4
info depth 6 currmovenumber 1 currmove c7c8R time 1 nodes 1002 hashfull 0
info depth 6 seldepth 5 score cp 735 time 2 nodes 1119 hashfull 0 pv c7c8R d4a4 c2b3 a1b1 b3a4 b1b2
info depth 7 currmovenumber 1 currmove c7c8R time 2 nodes 1522 hashfull 0
info depth 7 seldepth 7 score cp 734 time 2 nodes 1744 hashfull 0 pv c7c8R d4a4 c2b3 a1b1 b3a4 b1b2 a4b5
info depth 8 currmovenumber 1 currmove c7c8R time 2 nodes 2276 hashfull 0
info depth 8 seldepth 9 score cp 737 time 3 nodes 4392 hashfull 0 pv c7c8R d4a4 c2b3 a1b1 b3a4 b1a2 a4b4 a2b2
info depth 9 currmovenumber 1 currmove c7c8R time 3 nodes 5456 hashfull 0
info depth 9 seldepth 10 score cp 735 time 3 nodes 6284 hashfull 0 pv c7c8R d4a4 c2b3 a1b1 b3a4 b1a2 a4b4 a2b2 b4c5
info depth 10 currmovenumber 1 currmove c7c8R time 4 nodes 9025 hashfull 0
info depth 10 seldepth 14 score cp 739 time 4 nodes 12035 hashfull 0 pv c7c8R d4a4 c2b3 a1b1 b3a4 b1b2 a4b4 b2a2 b4c4 a2b2
info depth 11 currmovenumber 1 currmove c7c8R time 5 nodes 21988 hashfull 0
info depth 11 seldepth 17 score mate 9 lowerbound time 6 nodes 28185 hashfull 0 pv c7c8R d4a4
info depth 11 currmovenumber 1 currmove c7c8R time 6 nodes 28185 hashfull 0
info depth 11 seldepth 17 score mate 8 time 9 nodes 76384 hashfull 0 pv c7c8R d4a4 c2b3 a4b4 b3b4 a1b2 b4a4 b2a2 c8c2 a2a1 a4b3 a1b1 c2c8 b1a1 c8c1
info depth 12 currmovenumber 1 currmove c7c8R time 15 nodes 175009 hashfull 0
info depth 12 seldepth 17 score mate 7 time 17 nodes 206408 hashfull 0 pv c7c8R d4a4 c2b3 a4b4 b3b4 a1b2 c8c4 b2a2 b4c3 a2a1 c3c2 a1a2 c4a4
info depth 13 currmovenumber 1 currmove c7c8R time 18 nodes 239231 hashfull 0
info depth 13 seldepth 17 score mate 7 time 19 nodes 279319 hashfull 0 pv c7c8R d4a4 c2b3 a4b4 b3b4 a1b2 c8c4 b2a2 b4c3 a2a1 c3c2 a1a2 c4a4
info depth 14 currmovenumber 1 currmove c7c8R time 21 nodes 318697 hashfull 0
info depth 14 seldepth 17 score mate 7 time 23 nodes 369000 hashfull 0 pv c7c8R d4a4 c2b3 a4b4 b3b4 a1b2 c8c4 b2a2 b4c3 a2a1 c3c2 a1a2 c4a4
info depth 15 currmovenumber 1 currmove c7c8R time 25 nodes 415000 hashfull 0
info depth 15 seldepth 17 score mate 7 time 27 nodes 479575 hashfull 0 pv c7c8R d4a4 c2b3 a4b4 b3b4 a1b2 c8c4 b2a2 b4c3 a2a1 c3c2 a1a2 c4a4
info depth 16 currmovenumber 1 currmove c7c8R time 29 nodes 527746 hashfull 0
info depth 16 seldepth 17 score mate 7 time 31 nodes 593525 hashfull 0 pv c7c8R d4a4 c2b3 a4b4 b3b4 a1b2 c8c4 b2a2 b4c3 a2a1 c3c2 a1a2 c4a4
info depth 17 currmovenumber 1 currmove c7c8R time 34 nodes 645379 hashfull 0
info depth 17 seldepth 17 score mate 7 time 36 nodes 720934 hashfull 0 pv c7c8R d4a4 c2b3 a4b4 b3b4 a1b2 c8c4 b2a2 b4c3 a2a1 c3c2 a1a2 c4a4
info depth 18 currmovenumber 1 currmove c7c8R time 39 nodes 772305 hashfull 0
info depth 18 seldepth 17 score mate 7 time 41 nodes 852591 hashfull 0 pv c7c8R d4a4 c2b3 a4b4 b3b4 a1b2 c8c4 b2a2 b4c3 a2a1 c3c2 a1a2 c4a4
info depth 19 currmovenumber 1 currmove c7c8R time 44 nodes 905539 hashfull 0
info depth 19 seldepth 17 score mate 7 time 47 nodes 984461 hashfull 0 pv c7c8R d4a4 c2b3 a4b4 b3b4 a1b2 c8c4 b2a2 b4c3 a2a1 c3c2 a1a2 c4a4
info depth 20 currmovenumber 1 currmove c7c8R time 49 nodes 1037697 hashfull 0
info depth 20 seldepth 17 score mate 7 time 52 nodes 1117264 hashfull 0 pv c7c8R d4a4 c2b3 a4b4 b3b4 a1b2 c8c4 b2a2 b4c3 a2a1 c3c2 a1a2 c4a4
info depth 21 currmovenumber 1 currmove c7c8R time 55 nodes 1171217 hashfull 0
info depth 38 seldepth 17 score mate 7 time 155 nodes 3537122 nps 22820141 hashfull 0 pv c7c8R d4a4 c2b3 a4b4 b3b4 a1b2 c8c4 b2a2 b4c3 a2a1 c3c2 a1a2 c4a4
info depth 38 currmovenumber 2 currmove c2b3 time 156 nodes 3537122 nps 22673858 hashfull 0
info depth 56 seldepth 17 score mate 7 time 258 nodes 5954741 nps 23080391 hashfull 0 pv c7c8R d4a4 c2b3 a4b4 b3b4 a1b2 c8c4 b2a2 b4c3 a2a1 c3c2 a1a2 c4a4
info depth 56 currmovenumber 2 currmove c2b3 time 258 nodes 5954741 nps 23080391 hashfull 0
info depth 73 currmovenumber 3 currmove c2c3 time 359 nodes 8285324 nps 23078896 hashfull 0
info depth 91 seldepth 17 score mate 7 time 461 nodes 10673549 nps 23153034 hashfull 0 pv c7c8R d4a4 c2b3 a4b4 b3b4 a1b2 c8c4 b2a2 b4c3 a2a1 c3c2 a1a2 c4a4
info depth 91 currmovenumber 2 currmove c2b3 time 461 nodes 10673549 nps 23153034 hashfull 0
info depth 109 currmovenumber 1 currmove c7c8R time 561 nodes 13018256 nps 23205447 hashfull 0
info depth 120 seldepth 17 score mate 7 time 630 nodes 14637736 nps 23234501 hashfull 0 pv c7c8R d4a4 c2b3 a4b4 b3b4 a1b2 c8c4 b2a2 b4c3 a2a1 c3c2 a1a2 c4a4
bestmove c7c8R ponder d4a4
stop
bestmove c7c8R
quit

[pichy]

[d]8/2P5/8/8/3r4/8/2K5/k7 w - - 0 1

Are there engines that, when denied tablebases, fail to see a quick mate here?

Yes most top engines still do without the use of tablebase

Please give an example of a top engine that does not find mate-in-7 for the diagrammed position. Every top engine I have tried solves the position very quickly without tablebases.


That is NOT the original position, and you know it,this is the original position:!:

PS: Anyway here is where the original posting or thread started as you can study Komodo analysis after White Kc3-c2 Rd1-d4 c7-c8Q. Komodo does not select c7 c8= Rook to prevent stalemate :

[d]8/8/1KP5/3r4/8/8/8/k7 w - - 0 1

FEN: 8/8/1KP5/3r4/8/8/8/k7 w - - 0 1

Komodo3-64:
1 00:00 52 520,000 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4
2 00:00 203 203,111 +1.40 c6-c7 Ka1-b2 c7-c8Q
3 00:00 620 206,648 +1.44 c6-c7 Rd5-d2 c7-c8Q Rd2-b2+ Kb6-a5
4 00:00 1,043 260,768 +0.01 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1
5 00:00 1,278 319,523 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q
5 00:00 1,284 256,745 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q
6 00:00 1,629 271,476 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q
6 00:00 1,635 233,572 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q
7 00:00 2,290 254,422 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q
7 00:00 2,296 229,594 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q
8 00:00 3,374 281,142 +0.16 c6-c7
8 00:00 5,199 346,614 +0.63 c6-c7
8 00:00 6,804 378,007 +1.34 c6-c7
8 00:00 17,827 379,290 +1.78 c6-c7 Rd5-d3 c7-c8Q Ka1-b2 Qc8-h8+ Rd3-c3 Kb6-b5 Kb2-c2 Qh8-d4 Rc3-b3+ Kb5-c5
8 00:00 17,835 371,559 +1.78 c6-c7 Rd5-d3 c7-c8Q Ka1-b2 Qc8-h8+ Rd3-c3 Kb6-b5 Kb2-c2 Qh8-d4 Rc3-b3+ Kb5-c5
9 00:00 32,693 510,819 +1.79 c6-c7 Rd5-d3 c7-c8Q Ka1-b2 Qc8-c4 Rd3-c3 Qc4-e2+ Kb2-b3 Qe2-d2 Rc3-c4 Qd2-d1+ Kb3-a3 Qd1-e1 Ka3-b2
9 00:00 32,701 503,088 +1.79 c6-c7 Rd5-d3 c7-c8Q Ka1-b2 Qc8-c4 Rd3-c3 Qc4-e2+ Kb2-b3 Qe2-d2 Rc3-c4 Qd2-d1+ Kb3-a3 Qd1-e1 Ka3-b2
10 00:00 63,316 666,475 +1.81 c6-c7 Rd5-d3 c7-c8Q Ka1-b2 Qc8-c4 Rd3-c3 Qc4-d5 Kb2-a3 Qd5-d4 Ka3-b2 Kb6-a5 Kb2-c2 Qd4-e5
10 00:00 63,324 659,620 +1.81 c6-c7 Rd5-d3 c7-c8Q Ka1-b2 Qc8-c4 Rd3-c3 Qc4-d5 Kb2-a3 Qd5-d4 Ka3-b2 Kb6-a5 Kb2-c2 Qd4-e5
11 00:00 122,183 749,588 +1.84 c6-c7 Rd5-d3 c7-c8Q Ka1-b2 Qc8-e6 Rd3-c3 Kb6-b5 Kb2-a3 Qe6-d6+ Ka3-b2 Qd6-d5 Kb2-a3 Qd5-d4 Rc3-b3+ Kb5-c5
11 00:00 122,191 745,069 +1.84 c6-c7 Rd5-d3 c7-c8Q Ka1-b2 Qc8-e6 Rd3-c3 Kb6-b5 Kb2-a3 Qe6-d6+ Ka3-b2 Qd6-d5 Kb2-a3 Qd5-d4 Rc3-b3+ Kb5-c5
12 00:00 310,610 949,878 +1.89 c6-c7 Rd5-d3 c7-c8Q Ka1-b2 Qc8-h8+ Kb2-b3 Qh8-e5 Rd3-c3 Kb6-b5 Rc3-d3 Qe5-f5 Kb3-c3 Qf5-c5+ Kc3-d2 Qc5-f2+ Kd2-c1 Kb5-b6 Rd3-b3+ Kb6-c5
12 00:00 310,618 947,003 +1.89 c6-c7 Rd5-d3 c7-c8Q Ka1-b2 Qc8-h8+ Kb2-b3 Qh8-e5 Rd3-c3 Kb6-b5 Rc3-d3 Qe5-f5 Kb3-c3 Qf5-c5+ Kc3-d2 Qc5-f2+ Kd2-c1 Kb5-b6 Rd3-b3+ Kb6-c5
13 00:00 375,703 973,324 +1.89 c6-c7 Rd5-d3 c7-c8Q Ka1-b2 Qc8-h8+ Kb2-b3 Qh8-e5 Rd3-c3 Kb6-b5 Rc3-d3 Qe5-f5 Kb3-c3 Qf5-c5+ Kc3-d2 Qc5-f2+ Kd2-c1 Qf2-f4+ Rd3-d2 Qf4-c4+ Rd2-c2 Qc4-d4
13 00:00 375,711 970,826 +1.89 c6-c7 Rd5-d3 c7-c8Q Ka1-b2 Qc8-h8+ Kb2-b3 Qh8-e5 Rd3-c3 Kb6-b5 Rc3-d3 Qe5-f5 Kb3-c3 Qf5-c5+ Kc3-d2 Qc5-f2+ Kd2-c1 Qf2-f4+ Rd3-d2 Qf4-c4+ Rd2-c2 Qc4-d4
14 00:00 696,868 1,035,464 +1.73 c6-c7 Rd5-d6+
14 00:00 700,879 1,036,802 +1.26 c6-c7 Rd5-d6+
14 00:00 704,063 1,035,386 +0.55 c6-c7 Rd5-d6+
14 00:00 715,763 1,037,336 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
14 00:00 715,771 1,037,348 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
15 00:00 729,837 1,039,654 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
15 00:00 729,845 1,039,665 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
16 00:00 756,853 1,046,823 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
16 00:00 756,861 1,045,386 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
17 00:00 790,306 1,060,812 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
17 00:00 790,314 1,059,401 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
18 00:00 837,605 1,076,613 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
18 00:00 837,613 1,075,239 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
19 00:00 903,764 1,102,151 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
19 00:00 903,772 1,100,817 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
20 00:00 1,017,902 1,137,320 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
20 00:00 1,017,910 1,137,329 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
21 00:01 1,163,781 1,180,305 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
21 00:01 1,163,789 1,179,118 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
22 00:01 1,395,637 1,233,984 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
22 00:01 1,395,645 1,233,991 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
23 00:01 1,719,305 1,292,710 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
23 00:01 1,719,313 1,291,745 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
24 00:01 2,177,298 1,339,052 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
24 00:01 2,177,306 1,338,232 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
25 00:02 2,906,827 1,394,830 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
25 00:02 2,906,835 1,394,164 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
26 00:02 4,088,550 1,453,965 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
26 00:02 4,088,558 1,453,451 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
27 00:04 7,522,955 1,527,193 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
27 00:04 7,522,963 1,526,885 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
28 00:08 12,686,734 1,573,060 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
28 00:08 12,686,742 1,572,866 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
29 00:15 24,621,324 1,616,845 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
29 00:15 24,621,332 1,616,739 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
30 00:32 55,173,795 1,684,130 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
30 00:32 55,173,803 1,684,130 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
31 00:54 91,575,585 1,677,823 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
31 00:54 91,575,593 1,677,792 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
32 02:37 271,414,833 1,723,651 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
32 02:37 271,414,841 1,723,640 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
33 07:23 778,049,905 1,753,849 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4
33 07:23 778,067,178 1,753,829 0.00 c6-c7 Rd5-d6+ Kb6-b5 Rd6-d5+ Kb5-b4 Rd5-d4+ Kb4-c3 Rd4-d1 Kc3-c2 Rd1-d4 c7-c8Q Rd4-c4+ Qc8xc4 Stalemate






For example:

Code: Select all

Critter v1.4 64-bit SSE4, by Richard Vida
setoption name Tablebase Usage value Disable
setboard 8/2P5/8/8/3r4/8/2K5/k7 w - - 0 1
info string Opening book: "book.cbk" - 57853 entries [native]
info string GTB Init OK (5 piece set)
info string Using 8 thread(s), 2048 MB hash
go infinite
 2/ 4  00:00       162       0  +0.14 c8=R Ra4 Rb8
 2/ 4  00:00       309       0  +3.48 Kc3 Rd7 c8=Q
 3/ 4  00:00       718  718000  +3.51 Kc3 Ra4 c8=Q Ra3+ Kb4 Kb2 Qh8+ Ka2
 4/ 6  00:00       801  801000  +3.51 Kc3 Ra4 c8=Q Ra3+ Kb4 Kb2 Qh8+ Ka2
 5/ 7  00:00      1242 1242000  +0.00 Kc3 Rd1 Kc2 Rd4
 5/ 8  00:00      2121 2121000  +6.44 c8=R Rd2+ Kxd2 Kb2 Rc3 Ka2 Kc2
 6/10  00:00      2718 1359000  +6.37 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4
 7/10  00:00      3256 1628000  +6.47 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4 Kb1 Ka4
 8/10  00:00      3671 1835500  +6.44 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4 Kb1 Kc3 Kc1
 9/14  00:00      5577 1394250  +6.55 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4 Ka2 Rc2+ Ka1 Kb3 Kb1 Kc3 Ka1
10/16+ 00:00      7418 1483600  +6.95 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4 Ka2 Rc2+ Ka1 Kb3 Kb1 Rc3
10/16+ 00:00      7623 1270500  +7.36 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4 Ka2 Rc2+ Ka1 Kb3 Kb1 Rc3
10/16+ 00:00      7884 1126285  +7.97 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4 Ka2 Rc2+ Ka1 Kb3 Kb1 Rc3
10/16+ 00:00      8101 1012625  +8.88 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4 Ka2 Rc2+ Ka1 Kb3 Kb1 Rc3
10/16+ 00:00      8286  920666 +10.25 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4 Ka2 Rc2+ Ka1 Kb3 Kb1 Rc3
10/16+ 00:00      8499  944333 +12.31 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4 Ka2 Rc2+ Ka1 Kb3 Kb1 Rc3
10/16+ 00:00      8681  868100 +15.39 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4 Ka2 Rc2+ Ka1 Kb3 Kb1 Rc3
10/16+ 00:00      8855  805000 +20.01 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4 Ka2 Rc2+ Ka1 Kb3 Kb1 Rc3
10/16  00:00     10717  824384    +M8 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Rc6 Ka2 Rc2+ Ka1 Kb3 Kb1 Rc3 Ka1 Rc1#
11/16  00:00     11511  822214    +M8 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4 Ka2 Rc2+ Ka1 Kb3 Kb1 Rc3 Ka1 Rc1#
12/16  00:00     12460  778750    +M8 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4 Ka2 Rc2+ Ka1 Kb3 Kb1 Rc3 Ka1 Rc1#
13/16  00:00     13748  723578    +M8 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4 Ka2 Rc2+ Ka1 Kb3 Kb1 Rc3 Ka1 Rc1#
14/16  00:00     15281  727666    +M8 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4 Ka2 Rc2+ Ka1 Kb3 Kb1 Rc3 Ka1 Rc1#
15/16  00:00     18052  752166    +M8 c8=R Ra4 Kb3 Kb1 Kxa4 Kb2 Kb4 Ka2 Rc2+ Ka1 Kb3 Kb1 Rc3 Ka1 Rc1#
16/16  00:00     25988  866266    +M8 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Ka4 Ka2 Rc2+ Ka1 Kb3 Kb1 Rc3 Ka1 Rc1#
17/17  00:00     33244  949828    +M8 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Ka4 Ka2 Rc2+ Ka1 Kb3 Kb1 Rc3 Ka1 Rc1#
18/17  00:00     49222 1144697    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
19/17  00:00     59017 1180340    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
20/17  00:00     79051 1317516    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
21/17  00:00     98760 1390985    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
22/17  00:00    122724 1515111    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
23/17  00:00    161673 1666731    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
24/19  00:00    210858 1802205    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
25/19  00:00    280505 1961573    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
26/21  00:00    383137 2164615    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
27/21  00:00    579169 2518126    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
28/21  00:00    726296 2584683    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
29/21  00:00    935992 2674262    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
30/21  00:00   1206184 2818186    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
31/21  00:00   1520008 2917481    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
32/21  00:00   1929155 3052460    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
33/21  00:00   2374658 3166210    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
34/23  00:00   2920565 3288924    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
35/23  00:01   3550163 3400539    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
36/23  00:01   4308042 3554490    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
37/23  00:01   5129644 3630321    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
38/23  00:01   6138778 3780035    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
39/25  00:01   7363444 3920896    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
?40/25  00:02   8774903 4077557    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#
41/25  00:02  10268638 4227516    +M7 c8=R Ra4 Kb3 Rb4+ Kxb4 Kb2 Rc6 Ka2 Kc3 Ka1 Kc2 Ka2 Ra6#

bestmove c8=R ponder Ra4

time: 2689 nodes: 11531236 evals: 5055001 knps: 4288
phash: 75.86% evalcache: 0.49% lazy: 99.95% eg_recog: 2688801
splits: 41731

Code: Select all

Crafty v23.4 (8 cpus)

White(1): egtb off
White(1): setboard 8/2P5/8/8/3r4/8/2K5/k7 w - - 0 1
White(1): st 15
search time set to 15.00.
White(1): go
              time limit 15.00 (+0.00) (15.00)
              depth   time  score   variation (1)
starting thread 1 2 3 4 5 6 7 <done>
               15->   0.06  Mat08   1. c8=R Ra4 2. Kb3 Kb1 3. Kxa4 Kb2
                                    4. Rc7 Ka2 5. Rc2+ Ka1 6. Kb3 Kb1 7.
                                    Rc8 Ka1 8. Rc1# (s=2)
              time=0.06  mat=-4  n=170817  fh=91%  nps=1.0M
              extensions=11K qchecks=12K reduced=25K pruned=86K
              predicted=0  evals=10K  50move=0  EGTBprobes=0  hits=0
              SMP->  splits=15  aborts=0  data=7/512  elap=0.06
terminating SMP processes.

mate in 8 moves.

White(1): c8=R
              time used:   0.06

Code: Select all

spark-1.0
(c) 2009-2010 AJ Siemelink

inifile=spark.ini

book=spark.bbk, 4651 moves
book.file=spark.bbk
allocating hash...allocated 32Mb
starting threads...started 16 threads

initialized
% uci

id name spark-1.0
id author AJ Siemelink
option name UCI_EngineAbout type string default spark-1.0 by AJ Siemelink
option name UCI_Opponent    type string
option name UCI_AnalyseMode type check default false
option name Threads         type spin   default 16 min 1 max 16
option name Hash            type spin   default 32 min 1 max 4096
option name Ponder          type check  default true
option name MultiPV         type spin   default 1 min 1 max 256
option name MultiPVMargin   type spin   default 100 min 0 max 2000
option name OwnBook         type check  default true
option name eval.mobility.opening      type spin default 100 min 0 max 1000
option name eval.mobility.endgame      type spin default 100 min 0 max 1000
option name eval.passedpawns.opening   type spin default 100 min 0 max 1000
option name eval.passedpawns.endgame   type spin default 100 min 0 max 1000
option name eval.pawnstructure.opening type spin default 100 min 0 max 1000
option name eval.pawnstructure.endgame type spin default 100 min 0 max 1000
option name eval.kingattack            type spin default 100 min 0 max 1000
uciok
setoption name Threads value 8
setoption name Hash value 1024
position fen 8/2P5/8/8/3r4/8/2K5/k7 w - - 0 1
go infinite
info depth 1 currmovenumber 1 currmove c7c8Q time 0 nodes 0 hashfull 0
info depth 1 seldepth 0 score cp 0 time 1 nodes 71 hashfull 0 pv c7c8Q d4c4 c8c4
info depth 1 seldepth 0 score cp 1 time 1 nodes 95 hashfull 0 pv c7c8R d4a4
info depth 1 seldepth 0 score cp 640 time 1 nodes 211 hashfull 0 pv c2c3 d4d1 c7c8Q
info depth 2 currmovenumber 1 currmove c2c3 time 1 nodes 211 hashfull 0
info depth 2 seldepth 1 score cp -150 time 1 nodes 245 hashfull 0 pv c2c3 d4d1
info depth 2 seldepth 1 score cp 0 time 1 nodes 278 hashfull 0 pv c7c8Q d4c4 c8c4
info depth 2 seldepth 1 score cp 640 time 1 nodes 434 hashfull 0 pv c2b3 a1b1 c7c8Q
info depth 3 currmovenumber 1 currmove c2b3 time 1 nodes 443 hashfull 0
info depth 3 seldepth 2 score cp 640 time 1 nodes 468 hashfull 0 pv c2b3 a1b1 c7c8Q
info depth 3 seldepth 4 score cp 733 time 1 nodes 619 hashfull 0 pv c7c8R d4a4 c2b3 a1b1 b3a4
info depth 4 currmovenumber 1 currmove c7c8R time 1 nodes 622 hashfull 0
info depth 4 seldepth 4 score cp 733 time 1 nodes 674 hashfull 0 pv c7c8R d4a4 c2b3 a1b1 b3a4
info depth 5 currmovenumber 1 currmove c7c8R time 1 nodes 706 hashfull 0
info depth 5 seldepth 4 score cp 733 time 1 nodes 931 hashfull 0 pv c7c8R d4a4 c2b3 a1b1 b3a4
info depth 6 currmovenumber 1 currmove c7c8R time 1 nodes 1002 hashfull 0
info depth 6 seldepth 5 score cp 735 time 2 nodes 1119 hashfull 0 pv c7c8R d4a4 c2b3 a1b1 b3a4 b1b2
info depth 7 currmovenumber 1 currmove c7c8R time 2 nodes 1522 hashfull 0
info depth 7 seldepth 7 score cp 734 time 2 nodes 1744 hashfull 0 pv c7c8R d4a4 c2b3 a1b1 b3a4 b1b2 a4b5
info depth 8 currmovenumber 1 currmove c7c8R time 2 nodes 2276 hashfull 0
info depth 8 seldepth 9 score cp 737 time 3 nodes 4392 hashfull 0 pv c7c8R d4a4 c2b3 a1b1 b3a4 b1a2 a4b4 a2b2
info depth 9 currmovenumber 1 currmove c7c8R time 3 nodes 5456 hashfull 0
info depth 9 seldepth 10 score cp 735 time 3 nodes 6284 hashfull 0 pv c7c8R d4a4 c2b3 a1b1 b3a4 b1a2 a4b4 a2b2 b4c5
info depth 10 currmovenumber 1 currmove c7c8R time 4 nodes 9025 hashfull 0
info depth 10 seldepth 14 score cp 739 time 4 nodes 12035 hashfull 0 pv c7c8R d4a4 c2b3 a1b1 b3a4 b1b2 a4b4 b2a2 b4c4 a2b2
info depth 11 currmovenumber 1 currmove c7c8R time 5 nodes 21988 hashfull 0
info depth 11 seldepth 17 score mate 9 lowerbound time 6 nodes 28185 hashfull 0 pv c7c8R d4a4
info depth 11 currmovenumber 1 currmove c7c8R time 6 nodes 28185 hashfull 0
info depth 11 seldepth 17 score mate 8 time 9 nodes 76384 hashfull 0 pv c7c8R d4a4 c2b3 a4b4 b3b4 a1b2 b4a4 b2a2 c8c2 a2a1 a4b3 a1b1 c2c8 b1a1 c8c1
info depth 12 currmovenumber 1 currmove c7c8R time 15 nodes 175009 hashfull 0
info depth 12 seldepth 17 score mate 7 time 17 nodes 206408 hashfull 0 pv c7c8R d4a4 c2b3 a4b4 b3b4 a1b2 c8c4 b2a2 b4c3 a2a1 c3c2 a1a2 c4a4
info depth 13 currmovenumber 1 currmove c7c8R time 18 nodes 239231 hashfull 0
info depth 13 seldepth 17 score mate 7 time 19 nodes 279319 hashfull 0 pv c7c8R d4a4 c2b3 a4b4 b3b4 a1b2 c8c4 b2a2 b4c3 a2a1 c3c2 a1a2 c4a4
info depth 14 currmovenumber 1 currmove c7c8R time 21 nodes 318697 hashfull 0
info depth 14 seldepth 17 score mate 7 time 23 nodes 369000 hashfull 0 pv c7c8R d4a4 c2b3 a4b4 b3b4 a1b2 c8c4 b2a2 b4c3 a2a1 c3c2 a1a2 c4a4
info depth 15 currmovenumber 1 currmove c7c8R time 25 nodes 415000 hashfull 0
info depth 15 seldepth 17 score mate 7 time 27 nodes 479575 hashfull 0 pv c7c8R d4a4 c2b3 a4b4 b3b4 a1b2 c8c4 b2a2 b4c3 a2a1 c3c2 a1a2 c4a4
info depth 16 currmovenumber 1 currmove c7c8R time 29 nodes 527746 hashfull 0
info depth 16 seldepth 17 score mate 7 time 31 nodes 593525 hashfull 0 pv c7c8R d4a4 c2b3 a4b4 b3b4 a1b2 c8c4 b2a2 b4c3 a2a1 c3c2 a1a2 c4a4
info depth 17 currmovenumber 1 currmove c7c8R time 34 nodes 645379 hashfull 0
info depth 17 seldepth 17 score mate 7 time 36 nodes 720934 hashfull 0 pv c7c8R d4a4 c2b3 a4b4 b3b4 a1b2 c8c4 b2a2 b4c3 a2a1 c3c2 a1a2 c4a4
info depth 18 currmovenumber 1 currmove c7c8R time 39 nodes 772305 hashfull 0
info depth 18 seldepth 17 score mate 7 time 41 nodes 852591 hashfull 0 pv c7c8R d4a4 c2b3 a4b4 b3b4 a1b2 c8c4 b2a2 b4c3 a2a1 c3c2 a1a2 c4a4
info depth 19 currmovenumber 1 currmove c7c8R time 44 nodes 905539 hashfull 0
info depth 19 seldepth 17 score mate 7 time 47 nodes 984461 hashfull 0 pv c7c8R d4a4 c2b3 a4b4 b3b4 a1b2 c8c4 b2a2 b4c3 a2a1 c3c2 a1a2 c4a4
info depth 20 currmovenumber 1 currmove c7c8R time 49 nodes 1037697 hashfull 0
info depth 20 seldepth 17 score mate 7 time 52 nodes 1117264 hashfull 0 pv c7c8R d4a4 c2b3 a4b4 b3b4 a1b2 c8c4 b2a2 b4c3 a2a1 c3c2 a1a2 c4a4
info depth 21 currmovenumber 1 currmove c7c8R time 55 nodes 1171217 hashfull 0
info depth 38 seldepth 17 score mate 7 time 155 nodes 3537122 nps 22820141 hashfull 0 pv c7c8R d4a4 c2b3 a4b4 b3b4 a1b2 c8c4 b2a2 b4c3 a2a1 c3c2 a1a2 c4a4
info depth 38 currmovenumber 2 currmove c2b3 time 156 nodes 3537122 nps 22673858 hashfull 0
info depth 56 seldepth 17 score mate 7 time 258 nodes 5954741 nps 23080391 hashfull 0 pv c7c8R d4a4 c2b3 a4b4 b3b4 a1b2 c8c4 b2a2 b4c3 a2a1 c3c2 a1a2 c4a4
info depth 56 currmovenumber 2 currmove c2b3 time 258 nodes 5954741 nps 23080391 hashfull 0
info depth 73 currmovenumber 3 currmove c2c3 time 359 nodes 8285324 nps 23078896 hashfull 0
info depth 91 seldepth 17 score mate 7 time 461 nodes 10673549 nps 23153034 hashfull 0 pv c7c8R d4a4 c2b3 a4b4 b3b4 a1b2 c8c4 b2a2 b4c3 a2a1 c3c2 a1a2 c4a4
info depth 91 currmovenumber 2 currmove c2b3 time 461 nodes 10673549 nps 23153034 hashfull 0
info depth 109 currmovenumber 1 currmove c7c8R time 561 nodes 13018256 nps 23205447 hashfull 0
info depth 120 seldepth 17 score mate 7 time 630 nodes 14637736 nps 23234501 hashfull 0 pv c7c8R d4a4 c2b3 a4b4 b3b4 a1b2 c8c4 b2a2 b4c3 a2a1 c3c2 a1a2 c4a4
bestmove c7c8R ponder d4a4
stop
bestmove c7c8R
quit

=========================================================================================================================

In the position that you posted even this low rated engine can find the correct move c7-c8=Rook and Mate in 7


FEN: 8/2P5/8/8/3r4/8/2K5/k7 w - - 0 1

Clueless:
1 00:00 3 3.000 +4.59 c7c8Q
2 00:00 74 74.000 -4.89 c7c8N Rd4c4+ Kc2d2
2 00:00 138 138.000 +0.08 c7c8R Ka1a2
2 00:00 214 214.000 +4.59 c7c8Q Ka1a2
3 00:00 362 362.000 0.00 c7c8Q Rd4c4+ Qc8xc4
3 00:00 561 561.000 +0.16 c7c8R Rd4a4 Kc2d3
4 00:00 1.094 1.094.000 -4.77 c7c8N Rd4c4+ Kc2d2 Rc4xc8 Kd2e2
4 00:00 1.376 1.376.000 +0.12 c7c8R Rd4a4 Kc2d3 Ka1b2
4 00:00 3.302 3.302.000 +2.29 Kc2b3 Rd4d7 c7c8Q
5 00:00 4.811 4.811.000 +2.31 Kc2b3 Rd4d3+ Kb3c4 Rd3c3+ Kc4xc3 Ka1a2
6 00:00 10.474 10.474.000 +0.16 Kc2b3 Rd4d3+ Kb3b4 Rd3d4+ Kb4c5 Rd4d1 c7c8R
6 00:00 12.649 12.649.000 +4.89 c7c8R Rd4a4 Kc2b3 Ka1b1 Kb3xa4 Kb1a1
7 00:00 24.034 1.413.764 -4.89 c7c8N Rd4c4+ Kc2d2 Rc4xc8 Kd2e3 Ka1b2 Ke3f4 Kb2c1
7 00:00 25.948 1.526.352 +4.89 c7c8R Rd4a4 Kc2b3 Ra4b4+ Kb3xb4 Ka1b2 Rc8a8 Kb2c1
8 00:00 40.870 2.404.117 -4.89 c7c8N Rd4c4+ Kc2d2 Rc4xc8 Kd2e3 Rc8f8 Ke3e2 Ka1b2 Ke2e1
8 00:00 44.055 2.591.470 +5.01 c7c8R Rd4a4 Kc2b3 Ka1b1 Kb3xa4 Kb1b2 Rc8b8+ Kb2a2 Rb8a8
9 00:00 90.989 1.895.604 -4.89 c7c8N Rd4c4+ Kc2d3 Rc4xc8 Kd3e4 Rc8f8 Ke4d5 Ka1a2 Kd5d6 Ka2a3
9 00:00 101.113 2.106.520 +5.26 c7c8R Rd4a4 Kc2b3 Ka1b1 Kb3xa4 Kb1b2 Ka4b4 Kb2b1 Kb4c3
10 00:00 181.418 2.296.430 -4.89 c7c8N Rd4c4+ Kc2d3 Rc4xc8 Kd3e4 Ka1b2 Ke4f4 Rc8g8 Kf4f5 Kb2c3 Kf5f4
10 00:00 196.146 2.064.694 +5.26 c7c8R Rd4a4 Kc2b3 Ka1b1 Kb3xa4 Kb1b2 Ka4b4 Kb2b1 Kb4a3 Kb1a1
11 00:00 333.218 2.122.407 -4.89 c7c8N Rd4c4+ Kc2d3 Rc4xc8 Kd3e4 Ka1b2 Ke4e5 Kb2c3 Ke5e6 Kc3c4 Ke6d7 Rc8g8
11 00:00 361.332 2.088.624 +5.26 c7c8R Rd4a4 Kc2b3 Ka1b1 Kb3xa4 Kb1b2 Rc8a8 Kb2c2 Ra8b8 Kc2d3 Ka4b3
12 00:00 680.675 2.174.680 -4.89 c7c8N Rd4c4+ Kc2d3 Rc4xc8 Kd3e4 Ka1a2 Ke4d4 Ka2a3 Kd4e4 Ka3b4 Ke4f4 Kb4c4 Kf4g4
12 00:00 740.580 2.152.848 +5.26 c7c8R Rd4a4 Kc2b3 Ka1b1 Kb3xa4 Kb1b2 Rc8a8 Kb2c2 Ka4a3 Kc2b1 Ra8a4 Kb1c1
13 00:00 1.194.517 2.183.760 -4.89 c7c8N Rd4c4+ Kc2d3 Rc4xc8 Kd3e4 Ka1a2 Ke4d5 Ka2a3 Kd5d6 Ka3b4 Kd6d7 Rc8c4 Kd7d8 Kb4b5
13 00:00 1.340.476 2.197.501 +5.39 c7c8R Rd4a4 Kc2b3 Ka1b1 Kb3xa4 Kb1b2 Ka4b4 Kb2a2 Kb4c3 Ka2a1 Rc8a8+ Ka1b1 Kc3b3 Kb1c1
14 00:01 2.172.846 2.244.675 -5.01 c7c8N Rd4c4+ Kc2d3 Rc4xc8 Kd3e4 Ka1b2 Ke4f5 Kb2c3 Kf5g4 Kc3d4 Kg4h4 Kd4e4 Kh4h5 Ke4f4 Kh5h4
14 00:01 2.618.044 2.205.597 +M7 c7c8R Rd4a4 Kc2b3 Ka1b1 Kb3xa4 Kb1b2 Ka4b4 Kb2a2 Kb4c3 Ka2a1 Kc3c2 Ka1a2 Rc8a8+
15 00:02 4.318.704 2.230.735 -5.01 c7c8N Rd4c4+ Kc2d3 Rc4xc8 Kd3e4 Rc8c6 Ke4f4
15 00:02 4.604.167 2.200.844 +M7 c7c8R Rd4a4 Kc2b3 Ka1b1 Kb3xa4 Kb1b2 Ka4b4 Kb2a2 Kb4c3 Ka2a1 Kc3c2 Ka1a2 Rc8a8+
16 00:03 7.237.068 2.208.443 -5.01 c7c8N Rd4c4+ Kc2d3 Rc4xc8 Kd3e4 Ka1a2 Ke4f4 Ka2a3 Kf4g4 Ka3b4 Kg4g5 Kb4c5 Kg5h5 Kc5d4 Kh5g5
16 00:03 7.702.216 2.183.786 +M7 c7c8R Rd4a4 Kc2b3 Ka1b1 Kb3xa4 Kb1b2 Ka4b4 Kb2a2 Kb4c3 Ka2a1 Kc3c2 Ka1a2 Rc8a8+

[lucasart]

[d]8/2P5/8/8/3r4/8/2K5/k7 w - -

Look more carefully and notice that K3 does play 6.c8=R here.

So it finds minor promotions from the root but not inside the search.

Is this a bug?

Not necessarily.

For game play removing all minor-promotions from the search gives a considerable speed-up in positions were promotions matter. It can be seen as a small ELO improvement.

Look at Rybka 1|2|3|4. Not one of those supports minor-promotions, not even at the root. I don't think that's a bug, it's deliberate.

Yes and no. I tested the following with DoubleCheck:
1/ remove under promotions alltogether: it was actually weaker!? not much so, but still significant
2/ remove underpromotions only in the qsearch: that actually was an improvement.

So now I consider all promotions in the search and only queen promotions in the qsearch.

Exactly what I am doing since my early days, skip them in QS only. And it gave a considerable saving because basically you remove 3 captures. Never tried it in the main search because I could not afford it anyway, see the user complaints at Rybka forum

One thing I haven't tried: sort underpromotions last in the main search. I suspect this is the best approach, but I need to do some testing before I put it in.

[bob]

[d]8/2P5/8/8/3r4/8/2K5/k7 w - -

Look more carefully and notice that K3 does play 6.c8=R here.

So it finds minor promotions from the root but not inside the search.

Is this a bug?

Not necessarily.

For game play removing all minor-promotions from the search gives a considerable speed-up in positions were promotions matter. It can be seen as a small ELO improvement.

Look at Rybka 1|2|3|4. Not one of those supports minor-promotions, not even at the root. I don't think that's a bug, it's deliberate.

Yes and no. I tested the following with DoubleCheck:
1/ remove under promotions alltogether: it was actually weaker!? not much so, but still significant
2/ remove underpromotions only in the qsearch: that actually was an improvement.

So now I consider all promotions in the search and only queen promotions in the qsearch.

Exactly what I am doing since my early days, skip them in QS only. And it gave a considerable saving because basically you remove 3 captures. Never tried it in the main search because I could not afford it anyway, see the user complaints at Rybka forum

One thing I haven't tried: sort underpromotions last in the main search. I suspect this is the best approach, but I need to do some testing before I put it in.

I don't think you want to do this. in 99% of promotions, the piece is immediately captured. If you try b8=Q, and the best reply is to play Rxb8, then you want to immediately try b8=R, =B and =N because those will be instant hash hits since after the capture you have the same position. If you delay the under-promotions, you run the risk of losing that hash entry.

I don't do underpromotions in q-search. Never have. I do do them in the main search. I did not see any Elo gain by removing them when I tested this the last time it came up a couple of years ago. I don't see any huge speed gain by taking them out, most likely for the above reason (hash hits).

[bob]

[d]8/2P5/8/8/3r4/8/2K5/k7 w - -

Look more carefully and notice that K3 does play 6.c8=R here.

So it finds minor promotions from the root but not inside the search.

Is this a bug?

Not necessarily.

For game play removing all minor-promotions from the search gives a considerable speed-up in positions were promotions matter. It can be seen as a small ELO improvement.

Look at Rybka 1|2|3|4. Not one of those supports minor-promotions, not even at the root. I don't think that's a bug, it's deliberate.

Yes and no. I tested the following with DoubleCheck:
1/ remove under promotions alltogether: it was actually weaker!? not much so, but still significant
2/ remove underpromotions only in the qsearch: that actually was an improvement.

So now I consider all promotions in the search and only queen promotions in the qsearch.

Exactly what I am doing since my early days, skip them in QS only. And it gave a considerable saving because basically you remove 3 captures. Never tried it in the main search because I could not afford it anyway, see the user complaints at Rybka forum

One thing I haven't tried: sort underpromotions last in the main search. I suspect this is the best approach, but I need to do some testing before I put it in.

I don't think you want to do this. in 99% of promotions, the piece is immediately captured. If you try b8=Q, and the best reply is to play Rxb8, then you want to immediately try b8=R, =B and =N because those will be instant hash hits since after the capture you have the same position. If you delay the under-promotions, you run the risk of losing that hash entry.

I don't do underpromotions in q-search. Never have. I do do them in the main search. I did not see any Elo gain by removing them when I tested this the last time it came up a couple of years ago. I don't see any huge speed gain by taking them out, most likely for the above reason (hash hits).

I have a test running now. This is an easy change. all moves are used at the root, including underpromotions. In the q-search Crafty has always only promoted to queen, so no change there. In the rest of the search, including the code that generates check evasions, the =N and =Q promotions remain, but =B and =R are no longer generated. After 4,000 games, no change at all. I have it set to play 60,000 games and will check and post the results in the AM...

I REALLY think this is a myth that the search is slowed down by the under promotions, in a significant way. But I will see. I also might compare speeds on a few problems like maybe WAC2 and fine70 where promotions happen...

Here's wac2 searched to depth=24 on a fairly slow box, first is normal crafty, second is version with no under-promotions inside search, just at root are they tried.

log.001: time=23.33 mat=0 n=44810989 fh=88% nps=1.9M
log.002: time=23.99 mat=0 n=46002132 fh=89% nps=1.9M

Tree grew slightly bigger for unknown reasons. Nps is the same.

Fine 70 to depth=45
log.001: time=20.28 mat=1 n=59299012 fh=89% nps=2.9M
log.002: time=19.13 mat=1 n=54818429 fh=89% nps=2.9M

Slightly smaller tree, same nps, about 5% faster, in what is likely a "best case" for this kind of thing

Finally a normal sort of tactical position, kopec 22 to depth=19:

log.001: time=30.93 mat=0 n=51913226 fh=94% nps=1.7M
log.002: time=31.51 mat=0 n=51897754 fh=94% nps=1.6M

Slighly smaller tree, slight drop in NPS, probably needs to be run more than once to see if there was any interference from another process...

pretty consistent:

log.001: time=31.40 mat=0 n=51913226 fh=94% nps=1.7M
log.002: time=31.55 mat=0 n=51897754 fh=94% nps=1.6M

Slightly slower, but not as much as last run. Up to 7,000 games now and the elo has dropped a bit, now at roughly -3, with an error bar of +/- 8, so may be no change when it is done...