George Tsavdaris wrote: ↑Thu Aug 23, 2018 7:37 am

Uri Blass wrote: ↑Thu Aug 23, 2018 2:49 am

If the target is to compose positions when it happens then it is easy

Here is an example from -114 to mate in 8.

Stockfish_18082021_x64_modern:

1/1 00:00 819 410k -114.55 1. ... Qhg4+ 2.Kc5

2/3 00:00 2k 771k -114.58 1. ... Qf2+ 2.Be3

3/6 00:00 3k 1,513k -114.85 1. ... Qh8+ 2.Ke3 Qxc3 3.Nxc3

4/8 00:00 5k 1,826k -114.37 1. ... Qh8+ 2.Ke3 Qhh3+ 3.Kf4 Qhg4+ 4.Ke5 Q4e4+ 5.Kf6

5/10 00:00 12k 2,477k -116.14 1. ... Qhg4+ 2.Bf4 Qxc2 3.Be6+ Kb8 4.Qxc7+ Qxc7 5.Qxc7+ Ka8 6.Bxg4

6/12 00:00 17k 2,877k -104.57 1. ... Qh8+ 2.Kc5 b6+ 3.Kb5 Qe8+ 4.Rd7 Qxd7+ 5.Nc6 Qgxc6+ 6.Kb4 Kb7

7/12 00:00 18k 2,998k -104.32 1. ... Qh8+ 2.Kc5 b6+ 3.Kb5 Qe8+ 4.Rd7 Qxd7+ 5.Nc6 Qgxc6+ 6.Kb4 Kb7 7.Qh8

8/17 00:00 26k 3,206k 0.00 1. ... Qh8+ 2.Ke3 Qh6+ 3.Kd4

9/13 00:00 33k 3,258k 0.00 1. ... Qh8+ 2.Ke3 Qh6+ 3.Kd4

10/15 00:00 35k 3,146k 0.00 1. ... Qh8+ 2.Ke3 Qh6+ 3.Kd4

11/13 00:00 48k 3,422k 0.00 1. ... Qh8+ 2.Ke3 Qh6+ 3.Kd4

12/19 00:00 58k 3,604k 0.00 1. ... Qh8+ 2.Ke3 Qh6+ 3.Kd4

13/15 00:00 74k 3,346k 0.00 1. ... Qh8+ 2.Ke3 Qh6+ 3.Kd4

14/12 00:00 88k 3,518k 0.00 1. ... Qh8+ 2.Ke3 Qh6+ 3.Kd4

15/19 00:00 107k 3,552k 0.00 1. ... Qh8+ 2.Ke3 Qh6+ 3.Kd4

16/15 00:00 145k 3,444k 0.00 1. ... Qh8+ 2.Ke3 Qh6+ 3.Kd4

17/14 00:00 187k 3,594k 0.00 1. ... Qh8+ 2.Ke3 Qh6+ 3.Kd4

18/17 00:00 258k 3,588k 0.00 1. ... Qh8+ 2.Ke3 Qh6+ 3.Kd4

19/18 00:00 323k 3,632k 0.00 1. ... Qh8+ 2.Ke3 Qh6+ 3.Kd4

20/19 00:00 412k 3,642k 0.00 1. ... Qh8+ 2.Ke3 Qh6+ 3.Kd4

21/19 00:00 554k 3,876k 0.00 1. ... Qh8+ 2.Ke3 Qh6+ 3.Kd4

22/25 00:00 689k 4,007k 0.00 1. ... Qh8+ 2.Ke3 Qh6+ 3.Kd4

23/24 00:00 902k 4,197k 0.00 1. ... Qh8+ 2.Ke3 Qh6+ 3.Kd4

24/23 00:00 1,360k 4,431k +M8 1. ... Qh8+ 2.Ke3 Qg5+ 3.Ke4 Qh7+ 4.Kd4 Qhg7+ 5.Ke4 Q7g6+ 6.Kd4 Q6f6+ 7.Ke4 Qff5+ 8.Kd4 Qe5+

Well not really this is the target, since engines have to keep for some time the "losing" score before they go to opposite evaluation.

In my position it keeps it for 1.6 billion nodes in yours it finds in a fraction of a second and 26000 nodes.

In this case try this trivial mate in 7 that I composed

Stockfish_18090410_x64_modern:

1/1 00:00 412 206k -28.99 1.Kf1

2/2 00:00 534 267k -28.87 1.Kf1 Bec5

3/4 00:00 862 431k -28.89 1.Nxd8 Bb4+ 2.Kf1 Bxd8

4/5 00:00 2k 1,001k -29.10 1.Kf1 Bad4 2.Nxd8 Bcxd8

5/6 00:00 4k 1,905k -29.29 1.Kf1 Bad4 2.Bd3 Bed6 3.Nxd8

6/6 00:00 8k 2,514k -29.33 1.Kf1 Bad4 2.Bd3 Bhg5 3.Nxd8 Bcxd8

7/10 00:00 14k 2,781k -29.30 1.Bd3 Kb7 2.Nxd8+ Bcxd8 3.Be4+ Kc7 4.Kf1 Bad4 5.Kg2

8/10 00:00 25k 3,568k -29.44 1.Bd3 Bh4+ 2.Ke2 Bdg5 3.Kf1 Baf2 4.Kg2 B8c5 5.Be4

9/11 00:00 36k 3,555k -29.40 1.Bd3 Bh4+ 2.Ke2 Bdg5 3.Be4 Bac5 4.Ne7+ Ka7 5.Nf5 Bb4 6.Nxh4

10/11 00:00 56k 3,308k -29.43 1.Bd3 Bh4+ 2.Kf1 Bdg5 3.Be4 Baf2 4.Ne7+ Ka7 5.Nf5 Bfd6

11/14 00:00 142k 3,639k -29.63 1.Kf1 Bad4 2.Kg2 Bb4 3.Kf3 Bd8f6 4.Kg2 Bbd6 5.Nxd4 Bxd4 6.Bc4 Bfe7

12/16 00:00 388k 4,038k -29.77 1.Kd1 Bgd4 2.Kc2 Bhe5 3.Bf1 Kb7 4.Bg2 Kb6 5.Nxd4 Bxd4 6.Bf1 Bce5 7.Be2

13/19 00:00 619k 4,453k -30.00 1.Kd1 Bgd4 2.Ke2 Bh8g7 3.Bd3 Kb7 4.Be4 Kb6 5.Kd3 Bhe3 6.Ke2 Bge5 7.Kf1 Beh6 8.Nxd4 Bxd4

14/20 00:00 864k 4,697k -30.02 1.Kd1 Bgd4 2.Ke2 Bhe5 3.Kf3 Bhe3 4.Kg2 Bab6 5.Kf1 Be7d6 6.Kg2 Bd8e7 7.Nxd4 Be3xd4 8.Bf1

15/21 00:00 1,165k 4,793k -30.03 1.Kd1 Bgd4 2.Ke2 Bhe5 3.Bd3 Kb7 4.Be4 Kb6 5.Kd1 Be7d6 6.Kc2 Bd8e7 7.Bg2 Bhe3 8.Nxd4 B3xd4 9.Kb3

16/20 00:00 1,794k 5,142k -30.12 1.Kd1 Bgd4 2.Ke2 Bhe3 3.Bd3 Kb7 4.Be4 Kb6 5.Kd1 Bhg7 6.Kc2 Bge5 7.Kd1 Bfg7 8.Kc2 Be7d6 9.Kb3

17/20 00:00 2,562k 5,371k -30.13 1.Kd1 Bgd4 2.Ke2 Bhe3 3.Kf3 Bhe5 4.Kg2 Bb4 5.Bc8 Bfd6 6.Kf1 Bab6 7.Kg2 B8e7 8.Nxb4 Bxb4 9.Bh3

18/21 00:00 3,126k 5,436k -30.11 1.Ke2 Bgd4 2.Kd3 Bhe3 3.Bc8 Bhe5 4.Kc2 Bfg7 5.Ba6 Bcd6 6.Kb3 Bd8c7 7.Bc8 Bab6 8.Ba6 B3g5 9.Nxd4 Bbxd4

19/24+ 00:03 20,760k 5,886k -29.37 1.Ke2

19/24+ 00:04 28,021k 5,948k -29.03 1.Ke2

19/24+ 00:05 32,160k 5,984k -28.58 1.Ke2

19/24+ 00:05 33,335k 5,993k -28.00 1.Ke2

19/24+ 00:05 34,923k 6,011k -27.26 1.Ke2

19/27+ 00:08 49,308k 6,128k -26.30 1.Ke2

19/27 00:14 93,851k 6,262k -25.98 1.Ke2 Bge5 2.Kd3 Bad4 3.Kc4 Bb4 4.Nxb4 Ka7 5.Bc8 Bxb4 6.Kxb4 Be7+ 7.Kc4 Bhe3 8.Bf5 Bhg7 9.Be4 Bcd6 10.Kb3 Kb6

20/16+ 00:15 99,140k 6,279k -25.89 1.Ke2

20/16+ 00:16 103,350k 6,290k -25.80 1.Ke2

20/25+ 00:20 130,440k 6,331k -25.67 1.Ke2

20/25+ 00:26 166,155k 6,329k -25.49 1.Ke2

20/25+ 00:32 208,042k 6,312k -25.24 1.Ke2

20/25+ 00:37 237,467k 6,325k -24.90 1.Ke2

20/25+ 00:41 262,348k 6,344k -24.45 1.Ke2

20/25+ 00:42 267,901k 6,348k -23.86 1.Ke2

20/25+ 00:44 283,516k 6,366k -23.11 1.Ke2

20/28 00:56 359,481k 6,405k -22.33 1.Ke2 Bh2 2.Kd3 Bc3 3.Kc4 Ba3 4.Kb5 Bh8e5 5.Nxd8 Bbc7 6.Nc6 Bfg7 7.Bc8 Bg5 8.Be6 Bab8 9.Bd5 Beg3 10.Ka6 Ba7

21/20+ 01:00 388,156k 6,419k -22.24 1.Ke2

21/20- 01:01 393,694k 6,422k -22.77 1.Ke2 Bgf6

21/20+ 01:01 394,153k 6,422k -22.28 1.Ke2

21/20+ 01:03 411,259k 6,429k -22.10 1.Ke2

21/28- 01:07 432,932k 6,436k -23.24 1.Ke2 Bce5

21/28+ 01:07 433,395k 6,435k -22.37 1.Ke2

21/28- 01:16 488,080k 6,396k -23.68 1.Ke2 Beg5

21/28+ 01:16 488,512k 6,396k -22.75 1.Ke2

21/28+ 01:16 489,659k 6,395k -22.00 1.Ke2

21/30 01:35 607,576k 6,357k -21.77 1.Ke2 Bd2 2.Kxd2 Bce5 3.Kd3 Bgf6 4.Kc4 Bb4 5.Nxb4 Bxb4 6.Kxb4 Bbd6+ 7.Kc4 Bad4 8.Bc8 Bhg7 9.Be6 Ka7 10.Bd5 B8b6 11.Kb5 Kb8 12.Kc4

22/28- 01:36 612,733k 6,355k -21.86 1.Ke2 Bd2

22/28+ 01:36 613,042k 6,356k -21.77 1.Ke2

22/28- 01:39 631,409k 6,351k -24.33 1.Ke2 Bce5

22/28+ 01:39 631,866k 6,351k -21.79 1.Ke2

22/29+ 01:55 726,740k 6,317k -21.54 1.Ke2

22/29 01:59 752,902k 6,318k -21.65 1.Ke2 Bh4 2.Kd3 Bb4 3.Nxb4 Bc5 4.Nc6 Bb4 5.Nxb4 Ka7 6.Bc8 Bde7 7.Nc6+ Kb6 8.Bd7 Bcd6 9.Ke2 Bd4 10.Kf1 Kc7 11.Nxb8 Kxb8 12.Be6 Bhe5 13.Kg2

23/31+ 01:59 755,916k 6,318k -21.56 1.Ke2

23/31+ 02:09 815,949k 6,303k -21.47 1.Ke2

23/31+ 02:19 881,203k 6,300k -21.34 1.Ke2

23/31+ 02:33 967,993k 6,295k -21.16 1.Ke2

23/31+ 02:49 1,069,305k 6,312k -20.91 1.Ke2

23/31+ 03:07 1,184,940k 6,319k -20.57 1.Ke2

23/31+ 03:13 1,225,500k 6,326k -20.13 1.Ke2

23/31+ 03:14 1,228,230k 6,326k -19.54 1.Ke2

23/31+ 03:30 1,329,993k 6,314k -18.79 1.Ke2

23/31+ 04:19 1,634,973k 6,300k -17.84 1.Ke2

23/33+ 05:36 2,100,650k 6,242k -16.62 1.Ke2

23/33+ 06:08 2,301,451k 6,243k -15.07 1.Ke2

23/34 06:51 2,570,369k 6,251k -13.68 1.Ke2 Bd2 2.Kxd2 Bb4+ 3.Kd3 Bgd4 4.Kc4 Bce5 5.Nxd8 Bab6 6.Nc6 Bd8 7.Nxd8 Bbc7 8.Nc6 Bba5 9.Kb5 Bhf6 10.Nxa5 Bxa5 11.Kxa5 Bfd6 12.Bc8 Ka7 13.Kb5

24/24- 06:51 2,571,379k 6,251k -14.92 1.Ke2 Bd2

24/24+ 06:53 2,584,376k 6,252k -13.68 1.Ke2

24/26- 07:02 2,640,287k 6,247k -16.85 1.Ke2 Bb4

24/26+ 07:02 2,641,360k 6,247k -14.28 1.Ke2

24/26+ 07:02 2,641,681k 6,247k -14.02 1.Ke2

24/26+ 07:03 2,644,675k 6,247k -13.69 1.Ke2

24/34+ 07:18 2,737,198k 6,241k -13.24 1.Ke2

24/34+ 07:22 2,762,259k 6,245k -12.66 1.Ke2

24/34+ 07:23 2,771,366k 6,242k -11.89 1.Ke2

24/34+ 07:31 2,824,007k 6,249k -10.93 1.Ke2

24/34+ 07:38 2,869,429k 6,253k -9.71 1.Ke2

24/34+ 07:47 2,923,419k 6,259k -8.17 1.Ke2

24/34+ 07:47 2,927,486k 6,259k -5.50 1.Ke2

24/34+ 07:51 2,955,565k 6,263k -3.03 1.Ke2

24/34+ 08:45 3,462,747k 6,595k +0.09 1.Ke2

24/34+ 08:45 3,464,577k 6,596k +4.00 1.Ke2

24/34+ 08:45 3,464,981k 6,596k +8.97 1.Ke2

24/34+ 08:45 3,469,188k 6,596k +16.05 1.Ke2

24/34+ 08:48 3,489,894k 6,599k +24.07 1.Ke2

24/34+ 08:50 3,503,654k 6,600k +36.72 1.Ke2

24/34+ 08:51 3,504,420k 6,599k +M21 1.Ke2

24/34 09:33 3,886,390k 6,777k +M9 1.Ke2 Bd2 2.Kxd2 Bh4 3.Kd3 Bb4 4.Kc4 Baf2 5.Kxb4 Bc3+ 6.Kb5 Bce1 7.Bc8 Bc5 8.Ka6 Bba7 9.Bb7+

25/16 09:35 3,905,622k 6,783k +M7 1.Ke2 Bd2 2.Kd3 Bda5 3.Kc4 Bgc3 4.Kb5 Bhd4 5.Bc8 Bfg7 6.Ka6 Bg3 7.Bb7+

26/14 09:41 3,941,668k 6,782k +M7 1.Ke2 Bd2 2.Kd3 Bda5 3.Kc4 Bgc3 4.Kb5 Bhd4 5.Bc8 Bfg7 6.Ka6 Bg3 7.Bb7+

Edit:Note that I made the problem relatively easy.

If the white king is at h1 it is mate in 8 and I could also put the black bishops to have more options in black squares(in my position bishops at b8 d8 f8 h8 cannot move and it make it easier for chess programs to solve).

Edit 2:I could even make it mate in 9 by havin Bf1-a6 as first move.