Looking for a mechanical solution to 11 Epd problems

[peter]

8/4ppkp/3p2p1/2pP1PP1/2P1P1P1/p7/K3B3/2b5 b - - acd 60; acs 1215; bm Bxg5; c0 "Bxg5 definitely wins. Does f6 win faster

Could well be:

8/4ppkp/3p2p1/2pP1PP1/2P1P1P1/p7/K3B3/2b5 b - - 0 1

Analysis by Stockfish 120415 64 POPCNT:

...
1...f6 2.fxg6 Kxg6 3.gxf6 Kxf6 4.Bf3 Kg5 5.Bd1 Kf4 6.Be2 Bb2 7.Bd1 h6 8.Kb3 Ke3 9.Kc2 Kd4 10.Be2 Bc3 11.Kb1 Kxe4 12.Ka2 Bb2 13.Kb3 Bc1 14.Bd1 Kd4 15.Be2 Ke3 16.Bd1 Kd2 17.Bf3 Kd3 18.Bd1 a2 19.Kxa2 Kxc4 20.Bf3 Kc3 21.Bg2 Bg5 22.Bf1 c4 23.Ka3 e6 24.Bg2 Kd2 25.Be4 exd5 26.Bh7 c3 27.Kb3 d4 28.Kc4 d3 29.Kd5 c2 30.Ke6 c1Q 31.Bg6 Ke3 32.Kf7 d2 33.Bf5 d1Q 34.Kg6 Qb2 35.Kh5 Qf6
-+ (-41.93) Depth: 69/102 00:06:59 7732MN
...
1...f6
-+ (-41.89 ++) Depth: 70/102 00:07:37 8536MN

After backward of 1...f6

[Dann Corbit]

It may not be a good idea to disable null move completely.
Instead I do the following.
Read in the variable LegalMov_GT as an UCI option.
Then you may set another variable MobilityVal by

if (LegalMov_GT == 0) MobilityVal=0;
else MobilityVal=MoveList<LEGAL>(pos).size();

before Step 8 in search.cpp.
And add
&& MobilityVal >= LegalMov_GT
to the if statement in Step 8
If you set LegalMov_GT to 0 nothing changes, but if you set
LegalMov_GT to say 11 you may get:
[d]1k3b1q/pP2p1p1/P1K1P1Pp/7P/2B5/8/8/8 w - - 0 1

Code: Select all

St-mod-15-04-22:
 38/5	00:00	 929k	1.397k	 0,00	Kc6-d7 Dh8-g8 Kd7-c6 Dg8-h8
 39/46	00:03	 6.693k	1.956k	+8,67	Kc6-d5 Dh8-g8 Kd5-e5 Dg8-h8 Lc4-b5 Dh8-g8
 40/49+	00:03	 6.859k	1.935k	+8,73	Kc6-d5
 40/49-	00:03	 7.464k	1.869k	+8,67	Kc6-d5 Dh8-g8
 40/49-	00:04	 8.949k	1.903k	+7,89	Kc6-d5 Dh8-g8
 40/52+	00:05	 10.775k	1.878k	+8,13	Kc6-d5
 40/56+	00:13	 30.976k	2.242k	+30,62	Kc6-d5
 40/58	00:17	 39.996k	2.293k	+31,81	Kc6-d5 Dh8-g8 Lc4-b5 Kb8-c7 Lb5-e8
 41/58-	00:17	 41.057k	2.301k	+31,75	Kc6-d5 Dh8-g8
 41/58+	00:17	 41.409k	2.302k	+31,81	Kc6-d5
 41/58-	00:18	 43.165k	2.310k	+31,75	Kc6-d5 Dh8-g8
 41/58+	00:19	 44.101k	2.316k	+31,83	Kc6-d5
 41/58+	00:22	 52.033k	2.300k	+42,05	Kc6-d5
 41/58-	00:22	 52.877k	2.300k	+39,02	Kc6-d5 Dh8-g8
 41/58-	00:23	 53.481k	2.310k	+31,00	Kc6-d5 Dh8-g8
 41/58+	00:23	 55.255k	2.325k	+37,22	Kc6-d5
 41/58+	00:26	 61.571k	2.361k	+55,12	Kc6-d5
 41/58	00:27	 64.967k	2.367k	+55,12	Kc6-d5 Dh8-g8 Lc4-b5 Kb8-c7 Lb5-a4

Kind regards
Bernhard

This seems to be a very clever and useful tactical setting.
In your opinion, what exactly are these changes doing that allows for quicker solutions to problems like this?

Also, rather than simply to disable null move, we might tweak the verification settings.

[Dann Corbit]

If anyone has mechanical solutions to any of these problems, I would be very glad to receive them.

[d]1k3b1q/pP2p1p1/P1K1P1Pp/7P/2B5/8/8/8 w - -

acd 127; acs 141; bm Kd7; c3 "Kd5"; ce 0; dm 27; id "Vincent Lejeune - hard CCC 2008 - Pos 29"; pm Kd7; pv Kd7 Qg8 Kc6 Qh8;

Not sure what you want. Have you tried using Sting or Stockfish Matefinder? Or simply disable nullmove pruning in Stockfish and recompile to get

Code: Select all

info depth 54 seldepth 64 multipv 1 score mate 27 nodes 19832454462 nps 35275883 hashfull 999 tbhits 0 time 562210 pv c4b5 h8g8 c6d5 b8c7 b5e8 c7b8 e8f7 g8h8 d5c6 h8g8 c6d7 g8h8 d7e8 b8c7 b7b8q c7b8 e8d7 b8a8 d7c7 h8g8 c7c8 g8f7 g6f7 g7g5 h5g6 h6h5 c8d7 a8b8 d7e8 f8g7 e8e7 b8c7 f7f8q g7f8 e7f8 h5h4 e6e7 h4h3 e7e8q h3h2 e8e5 c7c6 e5h2 c6b5 g6g7 b5b4 h2d2 b4b5 g7g8q b5a6 d2b2 a6a5 g8a2

Not sure this is minimal, since I haven't studied the output at all.

This is useful advice.
I may try both of those over the weekend.

[zullil]

These are from Vincent Lejeune's recent set of 115 chess problems. I have mechanical (computer generated) solutions to all but 11 of them. Some are incredibly difficult.

[d]4q1kr/p6p/1prQPppB/4n3/4P3/2P5/PP2B2P/R5K1 w - -
acd 52; acs 3487; bm Qa3; c0 "level: hard-16"; c1 "diff=10"; c3 "Qxe5"; ce 0; id "MG 4322"; pm Qa3; pv Qa3 Rxe6 Qxa7 Qe7 Qa8+ Qe8 Qb7 Qe7 Qa8+;

Stockfish (with null move pruning disabled) appears to see a win for White from here:
[d]4q1kr/p6p/1pr1P1pB/4p3/4P3/2P5/PP2B2P/R5K1 w - - 0 2

Code: Select all

info depth 49 seldepth 48 multipv 1 score cp 0 nodes 98653294423 nps 27797569 hashfull 999 tbhits 0 time 3548990 pv a1f1 c6c5 e2d1 c5c4 d1b3 b6b5 g1g2 a7a6 g2g3 e8e7 g3g2 e7e8
info depth 50 currmove a1f1 currmovenumber 1
info depth 50 seldepth 48 multipv 1 score cp 6 lowerbound nodes 159575071926 nps 28043822 hashfull 999 tbhits 0 time 5690204 pv a1f1
info depth 50 currmove a1f1 currmovenumber 1
info depth 50 seldepth 48 multipv 1 score cp 12 lowerbound nodes 168522104826 nps 28013752 hashfull 999 tbhits 0 time 6015692 pv a1f1
info depth 50 currmove a1f1 currmovenumber 1
info depth 50 seldepth 48 multipv 1 score cp 21 lowerbound nodes 182250885807 nps 28007677 hashfull 999 tbhits 0 time 6507176 pv a1f1
info depth 50 currmove a1f1 currmovenumber 1
info depth 50 seldepth 48 multipv 1 score cp 35 lowerbound nodes 188902482248 nps 27983202 hashfull 999 tbhits 0 time 6750567 pv a1f1
info depth 50 currmove a1f1 currmovenumber 1
info depth 50 seldepth 48 multipv 1 score cp 56 lowerbound nodes 202164218359 nps 27952074 hashfull 999 tbhits 0 time 7232530 pv a1f1
info depth 50 currmove a1f1 currmovenumber 1
info depth 50 seldepth 48 multipv 1 score cp 87 lowerbound nodes 225567070296 nps 27949737 hashfull 999 tbhits 0 time 8070454 pv a1f1
info depth 50 currmove a1f1 currmovenumber 1
info depth 50 seldepth 48 multipv 1 score cp 134 lowerbound nodes 262978709890 nps 27901838 hashfull 999 tbhits 0 time 9425139 pv a1f1
info depth 50 currmove a1f1 currmovenumber 1
info depth 50 seldepth 93 multipv 1 score cp 205 lowerbound nodes 306381855343 nps 28061073 hashfull 999 tbhits 0 time 10918394 pv a1f1
info depth 50 currmove a1f1 currmovenumber 1
info depth 50 seldepth 95 multipv 1 score cp 310 lowerbound nodes 506099306581 nps 28571891 hashfull 999 tbhits 0 time 17713189 pv a1f1
info depth 50 currmove a1f1 currmovenumber 1
info depth 50 currmove e6e7 currmovenumber 8
info depth 50 currmove e2h5 currmovenumber 16
info depth 50 currmove b2b4 currmovenumber 17
info depth 50 currmove h2h4 currmovenumber 18
info depth 50 currmove e2f1 currmovenumber 19
info depth 50 currmove a1e1 currmovenumber 25
info depth 50 currmove h6g7 currmovenumber 26
info depth 50 currmove e2d1 currmovenumber 27
info depth 50 currmove h2h3 currmovenumber 28
info depth 50 seldepth 95 multipv 1 score cp 352 nodes 673808681438 nps 28584192 hashfull 999 tbhits 0 time 23572773 pv a1f1 c6c8 e2d1 e8e6 d1b3 e6b3 a2b3 a7a5 f1f2 c8b8 c3c4 b8e8 g1g2 e8a8 g2g3 a8b8 g3g4 b8c8 f2f1 c8b8 g4g5 b8d8 g5f6 d8f8 h6f8 g8f8 c4c5 b6c5 b3b4 h8g8 b4a5 f8e8 f1d1 g6g5 f6e5 e8e7 a5a6 g5g4 a6a7 g8g5 e5f4 g5g8 d1d5 c5c4 d5h5 e7d6 h5h7 d6c5 e4e5 g8f8 f4e4 f8e8 e5e6

[zullil]

These are from Vincent Lejeune's recent set of 115 chess problems. I have mechanical (computer generated) solutions to all but 11 of them. Some are incredibly difficult.

[d]4q1kr/p6p/1prQPppB/4n3/4P3/2P5/PP2B2P/R5K1 w - -
acd 52; acs 3487; bm Qa3; c0 "level: hard-16"; c1 "diff=10"; c3 "Qxe5"; ce 0; id "MG 4322"; pm Qa3; pv Qa3 Rxe6 Qxa7 Qe7 Qa8+ Qe8 Qb7 Qe7 Qa8+;

Stockfish (with null move pruning disabled) appears to see a win for White from here:
[d]4q1kr/p6p/1pr1P1pB/4p3/4P3/2P5/PP2B2P/R5K1 w - - 0 2

Code: Select all

info depth 49 seldepth 48 multipv 1 score cp 0 nodes 98653294423 nps 27797569 hashfull 999 tbhits 0 time 3548990 pv a1f1 c6c5 e2d1 c5c4 d1b3 b6b5 g1g2 a7a6 g2g3 e8e7 g3g2 e7e8
info depth 50 currmove a1f1 currmovenumber 1
info depth 50 seldepth 48 multipv 1 score cp 6 lowerbound nodes 159575071926 nps 28043822 hashfull 999 tbhits 0 time 5690204 pv a1f1
info depth 50 currmove a1f1 currmovenumber 1
info depth 50 seldepth 48 multipv 1 score cp 12 lowerbound nodes 168522104826 nps 28013752 hashfull 999 tbhits 0 time 6015692 pv a1f1
info depth 50 currmove a1f1 currmovenumber 1
info depth 50 seldepth 48 multipv 1 score cp 21 lowerbound nodes 182250885807 nps 28007677 hashfull 999 tbhits 0 time 6507176 pv a1f1
info depth 50 currmove a1f1 currmovenumber 1
info depth 50 seldepth 48 multipv 1 score cp 35 lowerbound nodes 188902482248 nps 27983202 hashfull 999 tbhits 0 time 6750567 pv a1f1
info depth 50 currmove a1f1 currmovenumber 1
info depth 50 seldepth 48 multipv 1 score cp 56 lowerbound nodes 202164218359 nps 27952074 hashfull 999 tbhits 0 time 7232530 pv a1f1
info depth 50 currmove a1f1 currmovenumber 1
info depth 50 seldepth 48 multipv 1 score cp 87 lowerbound nodes 225567070296 nps 27949737 hashfull 999 tbhits 0 time 8070454 pv a1f1
info depth 50 currmove a1f1 currmovenumber 1
info depth 50 seldepth 48 multipv 1 score cp 134 lowerbound nodes 262978709890 nps 27901838 hashfull 999 tbhits 0 time 9425139 pv a1f1
info depth 50 currmove a1f1 currmovenumber 1
info depth 50 seldepth 93 multipv 1 score cp 205 lowerbound nodes 306381855343 nps 28061073 hashfull 999 tbhits 0 time 10918394 pv a1f1
info depth 50 currmove a1f1 currmovenumber 1
info depth 50 seldepth 95 multipv 1 score cp 310 lowerbound nodes 506099306581 nps 28571891 hashfull 999 tbhits 0 time 17713189 pv a1f1
info depth 50 currmove a1f1 currmovenumber 1
info depth 50 currmove e6e7 currmovenumber 8
info depth 50 currmove e2h5 currmovenumber 16
info depth 50 currmove b2b4 currmovenumber 17
info depth 50 currmove h2h4 currmovenumber 18
info depth 50 currmove e2f1 currmovenumber 19
info depth 50 currmove a1e1 currmovenumber 25
info depth 50 currmove h6g7 currmovenumber 26
info depth 50 currmove e2d1 currmovenumber 27
info depth 50 currmove h2h3 currmovenumber 28
info depth 50 seldepth 95 multipv 1 score cp 352 nodes 673808681438 nps 28584192 hashfull 999 tbhits 0 time 23572773 pv a1f1 c6c8 e2d1 e8e6 d1b3 e6b3 a2b3 a7a5 f1f2 c8b8 c3c4 b8e8 g1g2 e8a8 g2g3 a8b8 g3g4 b8c8 f2f1 c8b8 g4g5 b8d8 g5f6 d8f8 h6f8 g8f8 c4c5 b6c5 b3b4 h8g8 b4a5 f8e8 f1d1 g6g5 f6e5 e8e7 a5a6 g5g4 a6a7 g8g5 e5f4 g5g8 d1d5 c5c4 d5h5 e7d6 h5h7 d6c5 e4e5 g8f8 f4e4 f8e8 e5e6

Second try, again from the position after Qxe5 fxe5, with a clear hash. Much faster to see a highly positive score for White:

Code: Select all

info depth 41 seldepth 41 multipv 1 score cp 0 nodes 3494044748 nps 26010129 hashfull 900 tbhits 0 time 134334 pv a1f1 c6c7 e2d1 b6b5 d1b3 c7c4 a2a4 a7a6 g1g2 e8e7 f1f3 e7e8 f3f1
info depth 42 currmove a1f1 currmovenumber 1
info depth 42 seldepth 41 multipv 1 score cp 6 lowerbound nodes 4681497415 nps 26399322 hashfull 965 tbhits 0 time 177334 pv a1f1
info depth 42 currmove a1f1 currmovenumber 1
info depth 42 seldepth 41 multipv 1 score cp 12 lowerbound nodes 4938759659 nps 26389593 hashfull 972 tbhits 0 time 187148 pv a1f1
info depth 42 currmove a1f1 currmovenumber 1
info depth 42 seldepth 43 multipv 1 score cp 21 lowerbound nodes 5105054326 nps 26384073 hashfull 976 tbhits 0 time 193490 pv a1f1
info depth 42 currmove a1f1 currmovenumber 1
info depth 42 seldepth 52 multipv 1 score cp 35 lowerbound nodes 5291578610 nps 26384280 hashfull 981 tbhits 0 time 200558 pv a1f1
info depth 42 currmove a1f1 currmovenumber 1
info depth 42 seldepth 52 multipv 1 score cp 56 lowerbound nodes 5490119492 nps 26390364 hashfull 985 tbhits 0 time 208035 pv a1f1
info depth 42 currmove a1f1 currmovenumber 1
info depth 42 seldepth 52 multipv 1 score cp 87 lowerbound nodes 5980584683 nps 26503809 hashfull 989 tbhits 0 time 225650 pv a1f1
info depth 42 currmove a1f1 currmovenumber 1
info depth 42 seldepth 58 multipv 1 score cp 134 lowerbound nodes 6910071766 nps 26678783 hashfull 995 tbhits 0 time 259010 pv a1f1
info depth 42 currmove a1f1 currmovenumber 1
info depth 42 seldepth 67 multipv 1 score cp 205 lowerbound nodes 9102426782 nps 26877852 hashfull 999 tbhits 0 time 338659 pv a1f1
info depth 42 currmove a1f1 currmovenumber 1
info depth 42 currmove g1f2 currmovenumber 9
info depth 42 currmove e2h5 currmovenumber 10
info depth 42 currmove g1g2 currmovenumber 11
info depth 42 currmove e2b5 currmovenumber 17
info depth 42 currmove b2b3 currmovenumber 18
info depth 42 currmove a1d1 currmovenumber 19
info depth 42 currmove e2f1 currmovenumber 20
info depth 42 currmove c3c4 currmovenumber 21
info depth 42 currmove a2a4 currmovenumber 22
info depth 42 currmove e2d3 currmovenumber 23
info depth 42 currmove b2b4 currmovenumber 30
info depth 42 currmove a1e1 currmovenumber 32
info depth 42 seldepth 68 multipv 1 score cp 223 nodes 10976079227 nps 26801714 hashfull 999 tbhits 0 time 409529 pv a1f1 c6c7 e2d1 b6b5 d1b3 c7c4 f1f3 a7a6 g1g2 g6g5 a2a4 e8d8 g2g1 d8e7 f3f5 e7a7 g1f1 a7g7 h6g7 g8g7 b3c4 b5c4 f1e2 h8e8 f5e5 g7f6 e5f5 f6e6 f5g5 e8b8 e2e3 b8b2 g5h5 b2a2 a4a5 e6f7 h5h7 f7g6 h7c7 a2a5 c7c4 a5a2 h2h4 a6a5 c4c6 g6h5 c3c4 h5h4 c4c5 h4g5 c6a6 a2c2 e3d4

Code: Select all

info depth 43 seldepth 68 multipv 1 score cp 229 nodes 13094186045 nps 26837077 hashfull 999 tbhits 0 time 487914 pv a1f1 c6c7 e2d1 b6b5 d1b3 c7c4 f1f3 a7a6 g1g2 g6g5 a2a4 e8d8 g2g1 d8e7 f3f5 e7a7 g1f1 a7g7 h6g7 g8g7 b3c4 b5c4 f1f2 h8e8 f5e5 g7f6 e5f5 f6e6 f5g5 e8b8 f2e3 b8b2 g5h5 b2a2 a4a5 e6f7 h2h3 a2a1 e3d4 f7g7 h5d5 a1a2 d5c5 a2a1 c5c7 g7g8 e4e5 a1a5 e5e6 g8f8 c7h7

Code: Select all

info depth 44 seldepth 69 multipv 1 score cp 250 nodes 21733774456 nps 26940112 hashfull 999 tbhits 0 time 806744 pv a1f1 c6c7 e2d1 b6b5 d1b3 c7c4 f1f3 a7a6 a2a4 e8e7 g1g2 g6g5 f3f5 e7g7 h6g7 g8g7 b3c4 b5c4 g2f3 h8e8 f5e5 g7f6 e5f5 f6g6 f5c5 e8b8 f3e3 g6f6 e6e7 f6e7 c5g5 b8b2 g5g7 e7f8 g7h7 b2a2 e4e5 a2a4 e3d4 a4a2 h2h4 a2e2 h4h5 a6a5 h7a7 e2h2 a7a5 h2h5 d4c4 h5h2 a5a7 h2h1 c4d4 h1d1 d4e4 d1e1 e4f5 e1f1 f5e6

Will let this one run to see what happens...

[zullil]

These are from Vincent Lejeune's recent set of 115 chess problems. I have mechanical (computer generated) solutions to all but 11 of them. Some are incredibly difficult.

[d]4q1kr/p6p/1prQPppB/4n3/4P3/2P5/PP2B2P/R5K1 w - -
acd 52; acs 3487; bm Qa3; c0 "level: hard-16"; c1 "diff=10"; c3 "Qxe5"; ce 0; id "MG 4322"; pm Qa3; pv Qa3 Rxe6 Qxa7 Qe7 Qa8+ Qe8 Qb7 Qe7 Qa8+;

Stockfish (with null move pruning disabled) appears to see a win for White from here:
[d]4q1kr/p6p/1pr1P1pB/4p3/4P3/2P5/PP2B2P/R5K1 w - - 0 2

Code: Select all

info depth 49 seldepth 48 multipv 1 score cp 0 nodes 98653294423 nps 27797569 hashfull 999 tbhits 0 time 3548990 pv a1f1 c6c5 e2d1 c5c4 d1b3 b6b5 g1g2 a7a6 g2g3 e8e7 g3g2 e7e8
info depth 50 currmove a1f1 currmovenumber 1
info depth 50 seldepth 48 multipv 1 score cp 6 lowerbound nodes 159575071926 nps 28043822 hashfull 999 tbhits 0 time 5690204 pv a1f1
info depth 50 currmove a1f1 currmovenumber 1
info depth 50 seldepth 48 multipv 1 score cp 12 lowerbound nodes 168522104826 nps 28013752 hashfull 999 tbhits 0 time 6015692 pv a1f1
info depth 50 currmove a1f1 currmovenumber 1
info depth 50 seldepth 48 multipv 1 score cp 21 lowerbound nodes 182250885807 nps 28007677 hashfull 999 tbhits 0 time 6507176 pv a1f1
info depth 50 currmove a1f1 currmovenumber 1
info depth 50 seldepth 48 multipv 1 score cp 35 lowerbound nodes 188902482248 nps 27983202 hashfull 999 tbhits 0 time 6750567 pv a1f1
info depth 50 currmove a1f1 currmovenumber 1
info depth 50 seldepth 48 multipv 1 score cp 56 lowerbound nodes 202164218359 nps 27952074 hashfull 999 tbhits 0 time 7232530 pv a1f1
info depth 50 currmove a1f1 currmovenumber 1
info depth 50 seldepth 48 multipv 1 score cp 87 lowerbound nodes 225567070296 nps 27949737 hashfull 999 tbhits 0 time 8070454 pv a1f1
info depth 50 currmove a1f1 currmovenumber 1
info depth 50 seldepth 48 multipv 1 score cp 134 lowerbound nodes 262978709890 nps 27901838 hashfull 999 tbhits 0 time 9425139 pv a1f1
info depth 50 currmove a1f1 currmovenumber 1
info depth 50 seldepth 93 multipv 1 score cp 205 lowerbound nodes 306381855343 nps 28061073 hashfull 999 tbhits 0 time 10918394 pv a1f1
info depth 50 currmove a1f1 currmovenumber 1
info depth 50 seldepth 95 multipv 1 score cp 310 lowerbound nodes 506099306581 nps 28571891 hashfull 999 tbhits 0 time 17713189 pv a1f1
info depth 50 currmove a1f1 currmovenumber 1
info depth 50 currmove e6e7 currmovenumber 8
info depth 50 currmove e2h5 currmovenumber 16
info depth 50 currmove b2b4 currmovenumber 17
info depth 50 currmove h2h4 currmovenumber 18
info depth 50 currmove e2f1 currmovenumber 19
info depth 50 currmove a1e1 currmovenumber 25
info depth 50 currmove h6g7 currmovenumber 26
info depth 50 currmove e2d1 currmovenumber 27
info depth 50 currmove h2h3 currmovenumber 28
info depth 50 seldepth 95 multipv 1 score cp 352 nodes 673808681438 nps 28584192 hashfull 999 tbhits 0 time 23572773 pv a1f1 c6c8 e2d1 e8e6 d1b3 e6b3 a2b3 a7a5 f1f2 c8b8 c3c4 b8e8 g1g2 e8a8 g2g3 a8b8 g3g4 b8c8 f2f1 c8b8 g4g5 b8d8 g5f6 d8f8 h6f8 g8f8 c4c5 b6c5 b3b4 h8g8 b4a5 f8e8 f1d1 g6g5 f6e5 e8e7 a5a6 g5g4 a6a7 g8g5 e5f4 g5g8 d1d5 c5c4 d5h5 e7d6 h5h7 d6c5 e4e5 g8f8 f4e4 f8e8 e5e6

Second try, again from the position after Qxe5 fxe5, with a clear hash. Much faster to see a highly positive score for White:

Code: Select all

info depth 41 seldepth 41 multipv 1 score cp 0 nodes 3494044748 nps 26010129 hashfull 900 tbhits 0 time 134334 pv a1f1 c6c7 e2d1 b6b5 d1b3 c7c4 a2a4 a7a6 g1g2 e8e7 f1f3 e7e8 f3f1
info depth 42 currmove a1f1 currmovenumber 1
info depth 42 seldepth 41 multipv 1 score cp 6 lowerbound nodes 4681497415 nps 26399322 hashfull 965 tbhits 0 time 177334 pv a1f1
info depth 42 currmove a1f1 currmovenumber 1
info depth 42 seldepth 41 multipv 1 score cp 12 lowerbound nodes 4938759659 nps 26389593 hashfull 972 tbhits 0 time 187148 pv a1f1
info depth 42 currmove a1f1 currmovenumber 1
info depth 42 seldepth 43 multipv 1 score cp 21 lowerbound nodes 5105054326 nps 26384073 hashfull 976 tbhits 0 time 193490 pv a1f1
info depth 42 currmove a1f1 currmovenumber 1
info depth 42 seldepth 52 multipv 1 score cp 35 lowerbound nodes 5291578610 nps 26384280 hashfull 981 tbhits 0 time 200558 pv a1f1
info depth 42 currmove a1f1 currmovenumber 1
info depth 42 seldepth 52 multipv 1 score cp 56 lowerbound nodes 5490119492 nps 26390364 hashfull 985 tbhits 0 time 208035 pv a1f1
info depth 42 currmove a1f1 currmovenumber 1
info depth 42 seldepth 52 multipv 1 score cp 87 lowerbound nodes 5980584683 nps 26503809 hashfull 989 tbhits 0 time 225650 pv a1f1
info depth 42 currmove a1f1 currmovenumber 1
info depth 42 seldepth 58 multipv 1 score cp 134 lowerbound nodes 6910071766 nps 26678783 hashfull 995 tbhits 0 time 259010 pv a1f1
info depth 42 currmove a1f1 currmovenumber 1
info depth 42 seldepth 67 multipv 1 score cp 205 lowerbound nodes 9102426782 nps 26877852 hashfull 999 tbhits 0 time 338659 pv a1f1
info depth 42 currmove a1f1 currmovenumber 1
info depth 42 currmove g1f2 currmovenumber 9
info depth 42 currmove e2h5 currmovenumber 10
info depth 42 currmove g1g2 currmovenumber 11
info depth 42 currmove e2b5 currmovenumber 17
info depth 42 currmove b2b3 currmovenumber 18
info depth 42 currmove a1d1 currmovenumber 19
info depth 42 currmove e2f1 currmovenumber 20
info depth 42 currmove c3c4 currmovenumber 21
info depth 42 currmove a2a4 currmovenumber 22
info depth 42 currmove e2d3 currmovenumber 23
info depth 42 currmove b2b4 currmovenumber 30
info depth 42 currmove a1e1 currmovenumber 32
info depth 42 seldepth 68 multipv 1 score cp 223 nodes 10976079227 nps 26801714 hashfull 999 tbhits 0 time 409529 pv a1f1 c6c7 e2d1 b6b5 d1b3 c7c4 f1f3 a7a6 g1g2 g6g5 a2a4 e8d8 g2g1 d8e7 f3f5 e7a7 g1f1 a7g7 h6g7 g8g7 b3c4 b5c4 f1e2 h8e8 f5e5 g7f6 e5f5 f6e6 f5g5 e8b8 e2e3 b8b2 g5h5 b2a2 a4a5 e6f7 h5h7 f7g6 h7c7 a2a5 c7c4 a5a2 h2h4 a6a5 c4c6 g6h5 c3c4 h5h4 c4c5 h4g5 c6a6 a2c2 e3d4

Code: Select all

info depth 43 seldepth 68 multipv 1 score cp 229 nodes 13094186045 nps 26837077 hashfull 999 tbhits 0 time 487914 pv a1f1 c6c7 e2d1 b6b5 d1b3 c7c4 f1f3 a7a6 g1g2 g6g5 a2a4 e8d8 g2g1 d8e7 f3f5 e7a7 g1f1 a7g7 h6g7 g8g7 b3c4 b5c4 f1f2 h8e8 f5e5 g7f6 e5f5 f6e6 f5g5 e8b8 f2e3 b8b2 g5h5 b2a2 a4a5 e6f7 h2h3 a2a1 e3d4 f7g7 h5d5 a1a2 d5c5 a2a1 c5c7 g7g8 e4e5 a1a5 e5e6 g8f8 c7h7

Code: Select all

info depth 44 seldepth 69 multipv 1 score cp 250 nodes 21733774456 nps 26940112 hashfull 999 tbhits 0 time 806744 pv a1f1 c6c7 e2d1 b6b5 d1b3 c7c4 f1f3 a7a6 a2a4 e8e7 g1g2 g6g5 f3f5 e7g7 h6g7 g8g7 b3c4 b5c4 g2f3 h8e8 f5e5 g7f6 e5f5 f6g6 f5c5 e8b8 f3e3 g6f6 e6e7 f6e7 c5g5 b8b2 g5g7 e7f8 g7h7 b2a2 e4e5 a2a4 e3d4 a4a2 h2h4 a2e2 h4h5 a6a5 h7a7 e2h2 a7a5 h2h5 d4c4 h5h2 a5a7 h2h1 c4d4 h1d1 d4e4 d1e1 e4f5 e1f1 f5e6

Will let this one run to see what happens...

Code: Select all

info depth 51 seldepth 95 multipv 1 score cp 381 nodes 943726055457 nps 28078913 hashfull 999 tbhits 0 time 33609778 pv a1f1 c6c8 e2d1 b6b5 d1b3 c8c4 a2a3 a7a6 a3a4 e8e7 g1g2 e7e8 f1f3 e8e7 b3a2 e7g7 h6g7 g8g7 f3f7 g7h6 a2c4 b5c4 e6e7 h8e8 g2g3 g6g5 f7f6 h6g7 f6a6 e8e7 g3g4 e7b7 g4g5 g7f7 g5f5 b7b2 a6a7 f7e8 a4a5 e8d8 a5a6 b2a2 f5e5 d8c8 e5d6 c8b8 a7b7 b8a8 b7h7 a2a6 d6d5 a6a5 d5d4 a8b8 h2h4 b8c8 h4h5 c8d8 d4c4 d8e8 c4d4

[lech]

It is a very funny topic.
A mechanical solutions (?), and maybe mechanical programmers is better.
Or disable nullmove pruning or solution backward are a very funny too.
Why you need these impossible to solve for engines positions if you are not able to help in this question?

[peter]

Hi Louis!

Very nice position indeed!

Made a .pgn about it:

Code: Select all

[Event "CCC"]
[Site "?"]
[Date "2015.04.25"]
[Round "?"]
[White "Corbit, Dann"]
[Black "Zulli, Louis"]
[Result "1-0"]
[SetUp "1"]
[FEN "4q1kr/p6p/1prQPppB/4n3/4P3/2P5/PP2B2P/R5K1 w - -"]

1. Qxe5 $1 (1. Qa3 $2 Rxe6 2. Qxa7 Qe7 3. Qa8+ Qe8 4. Qb7 
Qe7 5. Qa8+ Qe8) 1... fxe5 2. Rf1 Rc8 (2... a6 3. Bd1 b5 
(3... Rc7 4. Bb3 Re7 5. Bd5 b5 6. Kg2 a5 7. a3 b4 8. axb4 
Qb8 9. b5 Qe8 10. b6 a4 11. b7 a3 12. Rf7 axb2 13. Rxe7 Qb5 
14. Re8+ Qxe8 15. e7+ Qf7 16. e8=Q#) 4. Bb3 Rc4 5. a4 Qe7 
6. Kg2) 3. Bd1 b5 4. Bb3 Rc4 5. a4 (5. Rf3) (5. a3 a6 6. a4 
Qe7 7. Kg2 Qe8 8. Rf3 (8. h3) 8... Qd8) 5... a6 6. Ba2 Qe7 
7. Kg2 Qg7 8. Bxc4 bxc4 9. Bxg7 Kxg7 10. Rf7+ 1-0

[peter]

These are from Vincent Lejeune's recent set of 115 chess problems. I have mechanical (computer generated) solutions to all but 11 of them. Some are incredibly difficult.

For instance, with this problem:
http://www.yacpdb.org/?id=340530
I tried creation of all the positions to the solution and then analyzing them backwards to feed the hash table. Eventually, the solution gets so far away that the engines get lost anyway.

If anyone has mechanical solutions to any of these problems, I would be very glad to receive them.

8/4ppkp/3p2p1/2pP1PP1/2P1P1P1/p7/K3B3/2b5 b - - acd 60; acs 1215; bm Bxg5; c0 "Bxg5 definitely wins. Does f6 win faster?"; c1 "diff=08"; c3 "f6"; c4 "(Dvor) 163"; ce 549; id "Dvoretsky.126"; pm Bxg5; pv Bxg5 fxg6 fxg6 Kxa3 Kf6 Kb2 Ke5 Kc2 Kxe4 Kd1 Bh4 Kd2 Kd4 Bf1 Bg3 Be2 Bf2 Bf1 Bh4 Be2 Bg3 Kc2 Ke3 Bd1 Be5 Kb3 Kd3 Bf3 Bf6 Bd1 Kd2 Bf3 Bd4 Ka3 Ke3 Bd1 Kf4 Be2 h5 gxh5 g5 Bf1 Kf3 h6 g4 h7 g3 Kb3 g2 Bxg2+ Kxg2 Kc2 Bf6 Kd3 Kf3 Kd2 Ke4 Kd1 Kd3 Ke1 Kxc4 Ke2 Kxd5;
8/1p2b3/6k1/5p2/p2NbP1p/P1B1P1p1/1P5P/6K1 w - - acd 65; acs 2720; bm Be1; c0 "Event:Smirin vs Computers; Site:KC-CB INT; Date:2002.04.24; Round: 6; Smirin, Ilia vs Hiarcs 8"; c1 "diff=10"; c3 "h3"; ce -26; pm Be1; pv Be1 gxh2+ Kxh2 Kh5 Kh3 Bd3 Nf3 Bf1+ Kh2 Bc5 Bd2 Bb6 Ne5 Bb5 Kg2 Bc5 Kf3 Be7 Bc3 Bf1 Kf2 Ba6 Kg2 Be2 Bd4 Bb5 Bc3 Bd6 Kh2 Bb8 Bd4 Bc7 Kg2 Ba5 Bc3 Bd8 Bd4 Bc7 Kh2 Ba5 Bc3 Bd8 Kg2 Bc6+ Kh2 Bc7 Bd4 Bd6 Nc4 Be7 Ne5 Bf8 Kh3 Bd6 Kh2 Bc7 Bc3 Be8 Bd4 Bd8 Kh3 Be7 Bc;
7r/p3k3/2p5/1pPp4/3P4/PP4P1/3P1PB1/2K5 w - - acd 68; acs 3468; bm Bf3; c0 "I think that Bf3 also draws. 68 plies and the engines can make no progress."; c1 "diff=10"; c3 "Kd1"; c4 "(Adorjan_EofCE3) #934 draw"; ce -205; id "EG 2059"; pm Bf3; pv Bf3 Rf8 Bg4 Rxf2 b4 Rf1+ Kc2 Kd8 Kb3 Kc7 Kc3 Rc1+ Kb3 Rg1 Bf5 Rxg3+ Kb2 Rf3 Bc2 Rf4 Kc3 a6 Bd1 Rf1 Bc2 Rf3+ Kb2 Rf2 Kc3 Kd7 Bb1 Rf6 Kb2 Kc8 Bc2 Rf2 Kc3 Rf3+ Kb2 Kb7 Bg6 Rf4 Kc3 Rh4 Bf5 Rh1 Bg6 Ra1 Kb3 Rf1 Kc3 Kb8 Be8 Rf6 Bh5 Rh6 Bg4 Rg6 Bf5 Rg3+ Kb2 Kb7 d;
7q/b1p5/1p1Npkb1/pPP2ppP/P1P5/3B2P1/5P1R/K3R3 w - - acd 44; acs 3228; bm Nb7; c0 "Incredibly difficult. Zugzwang involved."; c1 "diff=10"; c3 "hxg6"; ce 0; id "yacpdb id 340530"; pm Nb7; pv Nb7 Ke7+ Ka2 Qc3 Rd1 Qb4 Bc2 Qxc4+ Kb2 Qb4+ Bb3 bxc5 hxg6 c4 Nxa5 Qxa5 Bxc4 Qxa4 Bb3 Qxb5 Rh7+ Kf6 g7 Qe5+ Kb1 Qb5 Kb2;

The last one in this quote is the same as the one of the link you gave to Mihai Neghinas study (very first postion, without fen, but with the wrong "solution", I'd call it one of the allurement- lines after 1.Nb7?, 1.hxg6! instead wins as shown in the original study. BTW I gave a diagram of it too in my first posting in this thread

[zullil]

Hi Louis!

Very nice position indeed!

Made a .pgn about it:

Code: Select all

[Event "CCC"]
[Site "?"]
[Date "2015.04.25"]
[Round "?"]
[White "Corbit, Dann"]
[Black "Zulli, Louis"]
[Result "1-0"]
[SetUp "1"]
[FEN "4q1kr/p6p/1prQPppB/4n3/4P3/2P5/PP2B2P/R5K1 w - -"]

1. Qxe5 $1 (1. Qa3 $2 Rxe6 2. Qxa7 Qe7 3. Qa8+ Qe8 4. Qb7 
Qe7 5. Qa8+ Qe8) 1... fxe5 2. Rf1 Rc8 (2... a6 3. Bd1 b5 
(3... Rc7 4. Bb3 Re7 5. Bd5 b5 6. Kg2 a5 7. a3 b4 8. axb4 
Qb8 9. b5 Qe8 10. b6 a4 11. b7 a3 12. Rf7 axb2 13. Rxe7 Qb5 
14. Re8+ Qxe8 15. e7+ Qf7 16. e8=Q#) 4. Bb3 Rc4 5. a4 Qe7 
6. Kg2) 3. Bd1 b5 4. Bb3 Rc4 5. a4 (5. Rf3) (5. a3 a6 6. a4 
Qe7 7. Kg2 Qe8 8. Rf3 (8. h3) 8... Qd8) 5... a6 6. Ba2 Qe7 
7. Kg2 Qg7 8. Bxc4 bxc4 9. Bxg7 Kxg7 10. Rf7+ 1-0

This position is from the game below, or available at http://www.chessgames.com/perl/chessgame?gid=1472988

Here is the position after Black's 23rd move, with SF's current PV:
[d]4q1kr/p6p/1prQPppB/4n3/4P3/2P5/PP2B2P/R5K1 w - - 1 24

Code: Select all

info depth 50 seldepth 81 multipv 1 score cp 397 nodes 940558094988 nps 27958134 hashfull 999 tbhits 0 time 33641661 pv d6e5 f6e5 a1f1 a7a6 e2d1 b6b5 d1b3 c6c4 a2a4 e8e7 g1g2 e7e8 f1f3 e8e7 b3a2 e7g7 h6g7 g8g7 a2c4 b5c4 f3f7 g7h6 e6e7 h8e8 g2g3 g6g5 f7f6 h6g7 f6a6 e8e7 g3g4 e7b7 g4g5 g7f7 g5f5 b7b2 a6a7 f7e8 a4a5 e8d8 a5a6 b2a2 f5e5 d8c8 e5d5 c8b8 a7h7 a2a6 h2h4 b8c8 h4h5 c8d8 d5c4 d8e8 c4d5 a6a5 d5d4 e8f8 e4e5 a5a6 h5h6 f8g8 h7g7 g8h8

This PV was obtained by having SF search the position after 24. Qxe5 fxe5 (with 16 threads, 16 GB hash and null move pruning disbaled) until it saw a promising continuation for White. The search was then stopped but the hash table was left intact, and SF was given the position above. In short, "cheating" was involved. I don't know how long SF would take to find the key move Qxe5 with an empty hash table. But, in any case, we now have strong evidence that the sacrifice is sound, and wins with correct play.

[pgn]
[Event "Molniya Sporting Society"]
[Site "Chelyabinsk RUS"]
[Date "1946.??.??"]
[EventDate "?"]
[Round "5"]
[Result "1-0"]
[White "Yuri S Gusev"]
[Black "E Auerbach"]
[ECO "B70"]
[WhiteElo "?"]
[BlackElo "?"]
[PlyCount "73"]

1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 g6 6.Be2 Nc6 7.Nb3
Bg7 8.O-O Be6 9.f4 Rc8 10.f5 Bd7 11.g4 Ne5 12.g5 Ng8 13.Nd5 f6
14.Be3 b6 15.Nd4 Kf7 16.c3 Qe8 17.Ne6 Bxe6 18.fxe6+ Kf8
19.Nxf6 Nxf6 20.gxf6 Bxf6 21.Bh6+ Kg8 22.Rxf6 exf6 23.Qxd6 Rc6
24.Qxe5 fxe5 25.Rf1 Rc8 26.Bd1 Rc4 27.Bb3 b5 28.Bxc4 bxc4
29.b3 a5 30.bxc4 Qe7 31.Kg2 Qa3 32.Rf2 Qe7 33.Rf1 g5 34.Rf5 g4
35.c5 Qd8 36.c6 Qe7 37.c7 1-0
[/pgn]