The "iq" selection (test) - update

[lech]

I replaced 3 positions: 33, 72, 81.
Only a really intelligent engine is able to do this impossible task, it means to solve all the 100 carefully selected positions. Of course, without any human interference, tricks and tablebases.
This task doesn't contain some extremely strange dirty (anti-IQ) positions.
Click "d8" square to get pgn.
[pgn]

[Result "1"]
[FEN "rkr5/p5p1/Pp4Kp/8/3B4/1B6/8/8 w - - 0 1"]

1. Be5 {win}

[Result "2"]
[FEN "7k/6rp/6pN/1r4P1/3B4/8/8/K7 b - - 0 1"]

1... Rxg5

[Result "3"]
[FEN "1B1k4/3p4/1Kp5/PpP2p2/1PqP1P2/8/1P6/8 w - - 0 1"]

1. a6 {win}

[Result "4"]
[FEN "3N2r1/3Kp3/4Pk2/8/Bp6/6b1/2P5/8 b - - 0 1"]

1... Rxd8

[Result "5"]
[FEN "8/7p/5P1k/1p5P/5p2/2p1p3/P1P1P1P1/1K3Nb1 w - - 0 1"]

1. Ng3

[Result "6"]
[FEN "6q1/PpB5/k7/P6K/6n1/1P4p1/5p2/1B3N1N w - - 0 1"]

1. a8Q {or a8R}

[Result "7"]
[FEN "6k1/6p1/4Rb1p/p7/rp2P1N1/2P3P1/1P5P/6K1 b - - 0 1"]

1... Bxc3

[Result "8"]
[FEN "8/8/p2k1p2/1p1p3p/1P1P3p/P3NPP1/5K2/1b6 w - - 0 1"]

1. Ng2

[Result "9"]
[FEN "2k5/p7/Pp1p1b2/1P1P1p2/2P2P1p/3K3P/5B2/8 w - - 0 1"]

1. c5

[Result "10"]
[FEN "1n6/Pp1p1p1p/1P1P1P1P/4K3/2p5/p7/rpp1P3/qkb1R3 w - - 0 1"]

1. axb8N {win}

[Result "11"]
[FEN "1N4K1/1pp1p3/7k/2r3pP/p2pp1P1/P6N/8/2B5 w - - 0 1"]

1. Nc6

[Result "12"]
[FEN "5K2/k4p1p/5p1p/1p3p2/bP6/1p6/1P5p/7B w - - 0 1"]

1. Ke8 {or Ke7 win}

[Result "13"]
[FEN "k1b5/1p1p1p1p/1PpPpP2/2B5/8/2p1p2P/2PbP3/3K4 w - - 0 1"]

1. Bd4 {win}

[Result "14"]
[FEN "8/8/8/8/1kB1q3/8/1PRb4/1K6 b - - 0 1"]

1... Qh1 2. Ka2 Qa8 3.Kb1 Qe4 {or other way to get the start position position for white; win}

[Result "15"]
[FEN "8/1pN4r/5pkp/8/5K1p/2P4N/P3Bn2/8 w - - 0 1"]

1. Bh5

[Result "16"]
[FEN "4k1rr/1R1R3p/8/8/8/2K5/7P/8 w k - 0 1"]

1. Rd2

[Result "17"]
[FEN "5k2/4bp2/2B3p1/1P4p1/3R4/3P2PP/2r2PK1/8 b - - 0 1"]

1... Rxf2

[Result "18"]
[FEN "1b6/2p5/1kB5/1PN5/8/3K4/8/q7 w - - 0 1"]

1. Nb3

[Result "19"]
[FEN "N7/8/2KQ2rp/6k1/3p3p/2p4P/4PP2/5N2 w - - 0 1"]

1. f4

[Result "20"]
[FEN "2b1r3/r2ppN2/8/1p1p1k2/pP1P4/2P3R1/PP3PP1/2K5 w - - 0 1"]

1. Nd6

[Result "21"]
[FEN "8/8/4B3/6p1/7k/8/4pPKP/8 w - - 0 1"]

1. Bg4

[Result "22"]
[FEN "r7/7k/5R2/p3p3/Pp1pPp2/1PpP1Pp1/K1P3P1/8 w - - 0 1"]

1. Kb1 Kg7 {or 1... Rh8 2. Rf8} 2. Rh6

[Result "23"]
[FEN "1K3kB1/8/6p1/7R/8/4b3/8/6n1 w - - 0 1"]

1. Rh8 Kg7 2. Bh7

[Result "24"]
[FEN "8/8/R7/1b4k1/5p2/1B3r2/7P/7K w - - 0 1"]

1. h4 Kxh4 2. Rh6 Kg5 3. Rh5

[Result "25"]
[FEN "7Q/4p3/4p3/p1p1P3/Pp2P3/3Kp3/p1PbP3/kN6 w - - 0 1"]

1. Na3 bxa3 2. Qh1 Kb2 3. Qa1 Kxa1 4. c4

[Result "26"]
[FEN "4q1bk/PP4p1/1p4P1/8/1p3QPP/2Pp4/3P1pP1/K7 w - - 0 1"]

1. a8R {-> b8R}

[Result "27"]
[FEN "q7/b1p5/kp1p4/p2PN3/PPP5/1K6/8/5B2 w - - 0 1"]

1. c5 Kb7 2. Ba6 {win}

[Result "28"]
[FEN "1k1n4/1p1b1p2/1Bp1pPp1/1PP1P3/8/6P1/8/1K6 w - - 0 1"]

1. Bc7 {win}

[Result "29"]
[FEN "4q1kr/p6p/1prQPppB/4n3/4P3/2P5/PP2B2P/R5K1 w - - 0 1"]

1. Qxe5 {win}

[Result "30"]
[FEN "q1b4n/1p1pKp2/1p1p1Pp1/1P1P2Pp/2P4P/8/7R/1N1k4 w - - 0 1"]

1. Ra2 {win}

[Result "31"]
[FEN "3k4/2pq3p/pp5R/4P3/P6P/2PN4/1PN3K1/8 w - - 0 1"]

1. Nd4 {win}

[Result "32"]
[FEN "8/7p/6pP/p4pP1/3BpP2/p1KpP3/pn1N4/k7 w - - 0 1"]

1. Bh8 {win}

[Result "33"]
[FEN "3k4/8/7p/2p1p1pP/1pPpPpP1/1P1P1P2/N7/2K5 w - - 0 1"]

{Na2->h4}

[Result "34"]
[FEN "8/b4kp1/2p1p3/5pB1/p1PP4/1p6/3K1P2/3N4 w - - 0 1"]

1. Kc3

[Result "35"]
[FEN "1qN5/b1pB4/1pP2k2/pP3P2/P1P5/8/8/K7 w - - 0 1"]

{Ka1->h5->d8}

[Result "36"]
[FEN "8/3P3k/n2K3p/2p3n1/1b4N1/2p1p1P1/8/3B4 w - - 0 1"]

1. Nf6

[Result "37"]
[FEN "8/5K2/3p3p/3p3P/pp1P4/rkb1R3/p1p3P1/n1B2B2 w - - 0 1"]

1. Rd3 {win}

[Result "38"]
[FEN "6bn/p4p1k/rp3Pp1/rp2BBP1/1p6/pK6/P2P4/8 w - - 0 1"]

1. Bc8 {win}

[Result "39"]
[FEN "8/1p6/1Pp2N1q/p1Ppk2p/P3p3/3PPpPp/3K1P1P/2R5 w - - 0 1"]

1. Ng4 hxg4 2. d4 {next Rh1 and K->g1}

[Result "40"]
[FEN "8/P7/4k3/8/5P2/4Bq2/5P2/5K2 b - - 0 1"]

1... Kf5

[Result "41"]
[FEN "8/6kP/1p6/p7/Pr6/K2B4/8/8 b - - 0 1"]

{Rb4->h4 and next Kg7->e5(d5)}

[Result "42"]
[FEN "8/8/2b1N3/5p2/3B4/2K5/6kp/R7 w - - 0 1"]

1. Rh1

[Result "43"]
[FEN "8/8/4kpp1/3p1b2/p6P/2B5/6P1/6K1 b - - 0 1"]

1... Bh3

[Result "44"]
[FEN "5rk1/5ppp/p1Q1p3/1R6/q7/4b1P1/P2RPP1P/6K1 w - - 0 1"]

1. Rd8 {win}

[Result "45"]
[FEN "r7/1b1r4/k1p1p1p1/1p1pPpPp/p1PP1P1P/PP1K4/8/4Q3 w - - 0 1"]

1. Qa5

[Result "46"]
[FEN "3B4/1r2p3/r2p1p2/bkp1P1p1/1p1P1PPp/p1P4P/PPB1K3/8 w - - 0 1"]

1. Ba4

[Result "47"]
[FEN "2k5/2p5/1q1p4/pPpPp1pp/N1P1Pp2/P4PbP/KQ4P1/8 w - - 0 1"]

{avoid Nxb6}

[Result "48"]
[FEN "1r6/4k3/r2p2p1/2pR1p1p/2P1pP1P/pPK1P1P1/P7/1B6 b - - 0 1"]

1... Rxb3

[Result "49"]
[FEN "8/5k2/6P1/4B2p/6p1/2p3PP/p5P1/1n2K2R b K - 0 1"]

1... Kg8

[Result "50"]
[FEN "8/3k1b1r/2p1p1p1/rpPpPpPp/p2P1P1P/P2K4/8/4B3 w - - 0 1"]

1. Bb4

[Result "51"]
[FEN "7b/p1p1p3/P1PpPp2/2nP1kpr/5P1p/p3KBPP/P7/8 w - - 0 1"]

1. Be4

[Result "52"]
[FEN "7r/p1p1p1pk/3pPp1p/2pP1PP1/P1P4P/1K6/P6B/8 w - - 0 1"]

1. g6 Kg8 2. a5 a6 3. Bxd6 cxd6 4. h5 {or 2. Bxd6 cxd6 3. h5}

[Result "53"]
[FEN "8/1p1q2k1/1Pp5/p1Pp4/P2Pp1p1/4PpPp/1N3P1P/3B2K1 w - - 0 1"]

1. Bb3 Qc8 2. Nd1 Qa8 3. Bc4

[Result "54"]
[FEN "8/8/2pk4/8/p1p3B1/PpP5/1P6/r1NK4 w - - 0 1"]

1. Bf5 {-> Ra2 Nxa2}

[Result "55"]
[FEN "1R3b2/5ppQ/6Pp/6PP/R6P/P7/7K/2q1k3 w - - 0 1"]

1. Rb1 Qxb1 2. gxf7

[Result "56"]
[FEN "Kn6/8/8/3R2PB/8/2p2NP1/1q6/2k5 w - - 0 1"]

1. Rd1

[Result "57"]
[FEN "1B3B1B/2B5/p6B/8/8/8/8/1k1K4 w - - 0 1"]

1. Bce5

[Result "58"]
[FEN "4kr2/5p1K/3p1Q2/1p4P1/4P3/1PP5/7b/8 w - - 0 1"]

1. Kh6 {win}

[Result "59"]
[FEN "6R1/8/2pB3k/2P4p/5p1q/5P2/4P1K1/8 w - - 0 1"]

1. Bf8 {win}

[Result "60"]
[FEN "n2Bqk2/5p1p/Q4KP1/p7/8/8/8/8 w - - 0 1"]

1. Qc8 Kg8 2. Bc7 {win}

[Result "61"]
[FEN "8/5p2/8/8/p7/rpK4p/1p3ppr/bQ1N1bqk w - - 0 1"]

1. Kb4 {or Kd4 win}

[Result "62"]
[FEN "8/8/7p/3KNN1k/2p4p/8/3P2p1/8 w - - 0 1"]

1. Kc6

[Result "63"]
[FEN "1R6/pPk1r3/2p5/K7/8/2B1b3/8/8 w - - 0 1"]

1. Ka6

[Result "64"]
[FEN "8/p7/qkpN1p2/8/1B1P4/PP3K2/5P2/8 w - - 0 1"]

1. Ba5 {win}

[Result "65"]
[FEN "2N5/p7/P7/8/1KPp1p1p/3p1Bpp/3P2rq/R5bk w - - 0 1"]

1. Nb6 {win}

[Result "66"]
[FEN "5kN1/3p1q2/5P2/5PP1/2pK4/1p1R4/1P6/8 w - - 0 1"]

1. Rxb3

[Result "67"]
[FEN "2b1rk2/5p2/p1P5/2p2P2/2p5/7B/P7/2KR4 w - - 0 1"]

1. f6

[Result "68"]
[FEN "2r5/prkpR1p1/2p1ppK1/P1p1N1B1/P1P1P3/8/8/8 w - - 0 1"]

1. Bf4

[Result "69"]
[FEN "rk1b4/p2p2p1/1P6/2R2P2/8/2K5/8/5B2 w - - 0 1"]

1. Rc8 {win}

[Result "70"]
[FEN "3k4/4pp2/n2n4/5BN1/3N4/b7/4K3/8 w - - 0 1"]

1. Nxf7

[Result "71"]
[FEN "4b3/8/1P1K4/8/6p1/5pP1/5P1B/7k w - - 0 1"]

1. Kc5 Bg6 2. Kd4 Be8 3. b7 Bb5 4. b8R

[Result "72"]
[FEN "1r6/1n1R1b2/8/1p1p3k/pPpPp1p1/2P1P3/P2K1PP1/8 w - - 0 1"]

1.Rxb7

[Result "73"]
[FEN "8/p5p1/1pP3p1/p5p1/k3p3/4p3/K7/8 w - - 0 1"]

1. c7 {win}

[Result "74"]
[FEN "q7/8/2p5/B2p2pp/5pp1/2N3k1/6P1/7K w - - 0 1"]

1. Ne4 Kh4 2. Ng3 fxg3 3. Bb6

[Result "75"]
[FEN "q7/7R/k7/1p6/1p6/1P2B3/7K/8 w - - 0 1"]

1. Bd4 {win}

[Result "76"]
[FEN "1q1r3k/3P1pp1/ppBR1n1p/4Q2P/P4P2/8/5PK1/8 w - - 0 1"]

1. Rxf6

[Result "77"]
[FEN "1r3q1k/2N2P1p/6pQ/4p3/7p/n6P/3B4/7K w - - 0 1"]

1. Qf4 {win}

[Result "78"]
[FEN "5nr1/2Pp2pk/3Pp1p1/4P1P1/6P1/5K2/8/7n w - - 0 1"]

1. c8N

[Result "79"]
[FEN "2K3k1/1p6/R3p1p1/1rB1P1P1/8/8/1Pb5/8 w - - 0 1"]

1. Rc6

[Result "80"]
[FEN "4q3/2r1r2p/3P3P/1p6/kP6/Pp6/1P6/KB2R3 w - - 0 1"]

1. Rxe7 Qxe7 {or 1... Rxe7 2. dxe7} 2. dxc7

[Result "81"]
[FEN "r5b1/7P/p7/2B4p/rp15/4N1P1/p2R4/1k1K4 w - - 0 1"]

1. Rb2

[Result "82"]
[FEN "8/8/8/1k3p2/p1p1pPp1/PpPpP1Pp/1P1P3P/QNK2NRR w - - 0 1"]

{-> Qa2 win}

[Result "83"]
[FEN "4b1k1/P4pPp/1R3P1P/2r5/8/1P6/1K6/8 w - - 0 1"]

1. a8B

[Result "84"]
[FEN "4N2k/4PB1p/7P/B1p5/2P5/3q2Pp/1P3P1K/2r5 w - - 0 1"]

1. Bc3 Rxc3 2. Nc7

[Result "85"]
[FEN "1k6/3p4/1B6/4Pp1p/1p5R/1p4p1/pP3n2/K6n w - - 0 1"]

1. Rxh1 Nxh1 2. e6 dxe6 3. Bc7

[Result "86"]
[FEN "N3kb2/pq4p1/4B1P1/1p1P2B1/p7/3P4/2P5/2K5 w - - 0 1"]

1. Bf7 Kd7 2. Be6 Kd6 3. Bf4 Kc5 4. Be3 Kb4 5. Bd2 Ka3 6. Kb1

[Result "87"]
[FEN "8/1B3b1p/7P/p2p4/P2pp1kp/Q7/1N1Pq2P/7K w - - 0 1"]

1. Qh3

[Result "88"]
[FEN "1B2b2k/2N1qr2/4n2p/4p1PQ/1r2N3/1p6/7P/2KB4 w - - 0 1"]

1. Nd5 Rc4 2. Kb1 Rc1 3. Kb2 Rf2 4. Nf2 Rb1 5. Kb1 Qh7 6. g6 Bg6 7. Bc2 bxc2 8. Kc1 Bxh5 9. Be5

Ng7 10. Ne7

[Result "89"]
[FEN "2k4N/Q1np4/2p2Bpp/1p1P4/pPP1p2P/P7/7q/1K6 w - - 0 1"]

1. Nf7 Qg3 2. Qxc7 {win}

[Result "90"]
[FEN "8/4nk2/1p3p2/2rp2pp/1P1R1N1P/6P1/3KPP2/8 b - - 0 1"]

{avoid 1... Rb5}

[Result "91"]
[FEN "5BK1/5p1N/5Pp1/6Pk/8/1b6/8/7q b - - 0 1"]

1... Qa8 {-> Kxg5}

[Result "92"]
[FEN "2b5/1pr4p/3bp1pk/1p6/1PpN2PP/K1P1n3/P3N1R1/3R4 w - - 0 1"]

1. Nxb5 Nxd1 2. Nd6

[Result "93"]
[FEN "8/1p1pNpbk/q2P4/p3p2K/PP2N3/4P1P1/3P4/8 w - - 0 1"]

1. b5 Qb6 2. Nc8

[Result "94"]
[FEN "1rr5/6pk/7p/8/8/7P/1Pb1RRPK/8 b - - 0 1"]

{avoid Rxb2}

[Result "95"]
[FEN "6Q1/8/8/8/8/7k/ppp1p3/brrbK3 w - - 0 1"]

1. Qg1 {win}

[Result "96"]
[FEN "1B1K1k2/4N2p/3pP1pP/6p1/p7/3N2b1/2r2p2/8 w - - 0 1"]

1. Nc6 {win}

[Result "97"]
[FEN "8/4Pr1N/8/6PN/8/3K1ppp/4prkb/4Bbnn w - - 0 1"]

1. Nf8 {win}

[Result "98"]
[FEN "8/b7/3p2b1/5p1n/5Pk1/4P1p1/B5P1/R4K2 w - - 0 1"]

1. Ke2

[Result "99"]
[FEN "5K2/8/5B2/p7/8/p4p2/pn1PpPp1/kb2R3 w - - 0 1"]

1. Bh8 a4 2. Kg7 {win}

[Result "100"]
[FEN "3rqQ2/3ppppp/7k/R7/8/8/1PPP2K1/8 w - - 0 1"]

1. Ra3

[/pgn]

[lech]

The authors of studies:

by YACPDB:

Mendheim Julius - 1
Blathy Otto - 3, 12, 13
Benko Pal - 16, 75
Hasek Josef - 22, 28
Gurvich Abram - 23
Kasparyan Genrikh - 24
Neghina Mihai - 27
Grasemann Herbert - 37
Rudolph William - 46
Troitzky Aleksei - 57
Reti Richard - 58
Matous Mario - 60
Behting Carl - 62
Klyatskin Mikhail - 66
Kubbel Karl - 69
Novomesky Daniel - 73
Lazard Frederic - 74
Marwitz Jan - 79
Lamford Paul - 82
Simkhovich Froim - 86

by other sources:

Solovyov Y. - 6
Babic M. - 10
Neghina Mihai - 11, 31, 34, 35 (based on study), 84, 87, 89, 92
Simkhovich Froim - 20 (part of study)
Ganguly Surya - 33
van Breukelen Gijs - 36
Hoch Yehuda & Aloni Hillel - 55
Troitzky Aleksei - 59
Smyslov Vasily - 67
Bondarenko F. & Kuznetsov A. - 68
Illescas Miguel - 72
Zemlyanski Yuri - 81 (part of study)
Stavrietsky Aleksandr - 88
Kazantsev A. - 93
Ryabinin Nikolaj - 96
Neghina Mihai & Rusz Arpad- 97
Kamody Mario & Neghina Mihai - 98
Fekete Zoltan - 99 (part of study)

[Ajedrecista]

Hello:

Searching for unidentified authors, I found some of them, but the search is incomplete:

------------

#5: I found Fahrni (probably Hans Fahrni) and year 1922 from a CSS topic (ERET 032). The problem was reprinted at 'Soviet Chess Primer' by Maizelis according to this post.

------------

#8: This position comes from a real game: Karpov (1—0) Kasparov, WCC 1984-1985, game 9. Position after 46.- ..., gxh4:

https://www.chessgames.com/perl/chessgame?gid=1067121

[pgn][Event "Karpov - Kasparov World Championship Match 1984/85"]
[Site "Moscow URS"]
[Date "1984.10.05"]
[EventDate "?"]
[Round "9"]
[Result "1-0"]
[White "Anatoly Karpov"]
[Black "Garry Kasparov"]
[ECO "D34"]
[WhiteElo "?"]
[BlackElo "?"]
[PlyCount "139"]

1.d4 d5 2.c4 e6 3.Nf3 c5 4.cxd5 exd5 5.g3 Nf6 6.Bg2 Be7 7.O-O
O-O 8.Nc3 Nc6 9.Bg5 cxd4 10.Nxd4 h6 11.Be3 Re8 12.Qb3 Na5
13.Qc2 Bg4 14.Nf5 Rc8 15.Bd4 Bc5 16.Bxc5 Rxc5 17.Ne3 Be6
18.Rad1 Qc8 19.Qa4 Rd8 20.Rd3 a6 21.Rfd1 Nc4 22.Nxc4 Rxc4
23.Qa5 Rc5 24.Qb6 Rd7 25.Rd4 Qc7 26.Qxc7 Rdxc7 27.h3 h5 28.a3
g6 29.e3 Kg7 30.Kh2 Rc4 31.Bf3 b5 32.Kg2 R7c5 33.Rxc4 Rxc4
34.Rd4 Kf8 35.Be2 Rxd4 36.exd4 Ke7 37.Na2 Bc8 38.Nb4 Kd6 39.f3
Ng8 40.h4 Nh6 41.Kf2 Nf5 42.Nc2 f6 43.Bd3 g5 44.Bxf5 Bxf5
45.Ne3 Bb1 46.b4 gxh4 47.Ng2 hxg3 48.Kxg3 Ke6 49.Nf4+ Kf5
50.Nxh5 Ke6 51.Nf4+ Kd6 52.Kg4 Bc2 53.Kh5 Bd1 54.Kg6 Ke7
55.Nxd5+ Ke6 56.Nc7+ Kd7 57.Nxa6 Bxf3 58.Kxf6 Kd6 59.Kf5 Kd5
60.Kf4 Bh1 61.Ke3 Kc4 62.Nc5 Bc6 63.Nd3 Bg2 64.Ne5+ Kc3 65.Ng6
Kc4 66.Ne7 Bb7 67.Nf5 Bg2 68.Nd6+ Kb3 69.Nxb5 Ka4 70.Nd6 1-0[/pgn]

Karpov eventually found an played 47.- Kg2.

------------

#9: This position comes from a real game: Spassky (1—0) R. Byrne, Candidates Quarterfinal (1974), game 6. Position after 49.- ..., Kc8:

https://www.chessgames.com/perl/chessgame?gid=1128968

[pgn][Event "Spassky - Byrne Candidates Quarterfinal"]
[Site "San Juan PUR"]
[Date "1974.01.28"]
[EventDate "1974.01.14"]
[Round "6"]
[Result "1-0"]
[White "Boris Spassky"]
[Black "Robert Eugene Byrne"]
[ECO "B52"]
[WhiteElo "?"]
[BlackElo "?"]
[PlyCount "117"]

1. e4 c5 2. Nf3 d6 3. Bb5+ Bd7 4. Bxd7+ Qxd7 5. c4 e5 6. Nc3
Nc6 7. d3 g6 8. a3 Bg7 9. Rb1 Nge7 10. b4 b6 11. O-O O-O
12. Nd5 Nxd5 13. cxd5 Nd4 14. Nxd4 cxd4 15. Bd2 Rac8 16. Qb3
Rc7 17. Rbc1 Rfc8 18. b5 Rxc1 19. Rxc1 Rxc1+ 20. Bxc1 Qc7
21. Qc4 Qxc4 22. dxc4 f6 23. Kf1 Bf8 24. a4 Be7 25. Ke2 Kf7
26. Bd2 f5 27. exf5 gxf5 28. Kd3 Bf6 29. f3 h5 30. a5 Ke8
31. a6 Kd7 32. g3 Kc7 33. h3 Kd7 34. Ba5 Kc8 35. Be1 Kd7
36. Bf2 Ke8 37. Be1 Kf7 38. Bb4 Be7 39. f4 exf4 40. gxf4 Ke8
41. Kxd4 Kd7 42. Kd3 Kc7 43. Ke3 Bf6 44. Kf3 h4 45. Ke3 Bg7
46. Kd3 Bf6 47. Bd2 Kd7 48. Be3 Kc7 49. Bf2 Kc8 50. c5 dxc5
51. d6 Kd7 52. Bxc5 Bd8 53. Bb4 Ke6 54. Kc4 Bf6 55. Bc5 Bd8
56. Bd4 Kxd6 57. Be5+ Ke6 58. Bb8 Kd7 59. Kd5 1-0[/pgn]

Spassky eventually found an played 50.- Kg2.

------------

#17: I found this position in an old CCC post, which points to GMG3 suite. The position is labelled as "Larsen/Endings GMG 3.55" (link), but all the positions of that suite are labelled "Larsen/Endings".

------------

I stopped the quick search at #17 and might resume it. You are probably aware about positions from actual games and only interested about authors of studies.

Regards from Spain.

Ajedrecista.

[Paloma]

#26: -> b8R looses for white.

[lech]

Sorry, but I am not interested to know who is an author of this positions. For me it is not any important goal of this selection.

If you see -> , it is a "short cut". 1. a8R -> b8R means that 1. a8R leads to b8R in further solution.

[peter]

Searching for unidentified authors, I found some of them, but the search is incomplete:

Thanks for your recurring achivements in that job. Most of the IQ positions are quite well known already, some appearing in most of the bigger tactical test suites too, at least Lech gives hints where to look for the detailed sources anyhow, which isn't the case in most of the other collections neither, regards

[Ajedrecista]

Hello:

Sorry, but I am not interested to know who is an author of this positions. For me it is not any important goal of this selection.

If you see -> , it is a "short cut". 1. a8R -> b8R means that 1. a8R leads to b8R in further solution.

It is fine for me, I will not resume the search.

I made a little exception with #26, noted above in the thread: I did not see differences between 1.- a8=R and 1.- a8=Q. I found the problem at Arpad's blog, which tells that the original problem is longer (the underpromotion is the third move) and explains the difference between the promotion and the underpromotion, which I find helpful:

Chess Endgame Study Composition: WCCT-10 Study D047

Regards from Spain.

Ajedrecista.

[Vinvin]

The 3 new positions

#33 : Bring the knight to h4
[d]3k4/8/7p/2p1p1pP/1pPpPpP1/1P1P1P2/N7/2K5 w - -

#72 : 1.Rxb7!!
[d]1r6/1n1R1b2/8/1p1p3k/pPpPp1p1/2P1P3/P2K1PP1/8 w - -


#81 : 1. Rb2+!!
[d]r5b1/7P/p7/2B4p/rp6/4N1P1/p2R4/1k1K4 w - -

[ventura07]

The Fahrni position was published in the 8/9 issue of Schweizerische Schachzeitung in 1922 on p. 138. The author is shown as H. Fahrni, Bern (Study 283).

[Plutie]

#30 also has Nc3+ - if Kc1, then Kf8 wins, if Ke1, then Re2+, Kf1, and Ra2 wins.

[pgn][Event "?"]
[Site "?"]
[Date "2023.01.26"]
[Round "?"]
[White "Lc0 v0.30.0-dag+git.dirty"]
[Black "Lc0 v0.30.0-dag+git.dirty"]
[Result "*"]
[FEN "q1b4n/1p1pKp2/1p1p1Pp1/1P1P2Pp/2P4P/8/7R/1N1k4 w - - 0 1"]
[SetUp "1"]

1. Nc3+ {[%clk 00:02:51]} 1... Kc1 {[%clk 00:02:51]} 2. Kf8 {[%clk 00:02:53]}
2... Qa3 {[%clk 00:02:50]} 3. Ne2+ {[%clk 00:02:53]} 3... Kd2 {[%clk 00:02:37]}
4. Kg8 {[%clk 00:02:53]} 4... Qa1 {[%clk 00:02:28]} 5. Kxh8 {[%clk 00:02:55]}
5... Qe5 {[%clk 00:02:25]} 6. Nf4+ {[%clk 00:02:56]} 6... Kc3 {[%clk 00:02:22]}
7. Rf2 {[%clk 00:02:57]} 7... Qe1 {[%clk 00:02:20]} 8. Rf3+ {[%clk 00:02:56]}
8... Kxc4 {[%clk 00:02:18]} 9. Kg7 {[%clk 00:02:49]} 9... Qh1 {[%clk 00:01:59]}
10. Rh3 {[%clk 00:02:50]} 10... Qf1 {[%clk 00:01:54]} 11. Kxf7 {[%clk
00:02:52]} 11... Qxf4 {[%clk 00:01:55]} 12. Kg8 {[%clk 00:02:53]} 12... Qf5
{[%clk 00:01:54]} 13. Rh2 {[%clk 00:02:47]} 13... Qxd5+ {[%clk 00:01:35]} 14.
f7 {[%clk 00:02:48]} 14... Kxb5 {[%clk 00:01:35]} 15. Rc2 {[%clk 00:02:50]}
15... Qc6 {[%clk 00:01:34]} 16. Rb2+ {[%clk 00:02:43]} 16... Ka6 {[%clk
00:01:28]} 17. f8=Q {[%clk 00:02:44]} 17... Ka7 {[%clk 00:01:20]} 18. Kh7
{[%clk 00:02:32]} 18... d5 {[%clk 00:01:20]} 19. Qf2 {[%clk 00:02:23]} 19... d6
{[%clk 00:01:21]} 20. Kxg6 {[%clk 00:02:22]} 20... Qe8+ {[%clk 00:01:17]} 21.
Kg7 {[%clk 00:02:11]} 21... Qe5+ {[%clk 00:01:11]} 22. Qf6 {[%clk 00:02:13]}
22... Bf5 {[%clk 00:01:08]} *

[/pgn]