99 problem(s) found in 1438 milliseconds (displaying 99 problem(s)).

1 - P0007036
Noam D. Elkies
3370 U.S. Problem Bulletin 102/103 07-10/1995
Lob
P0007036
(15+13)
BP in 17,5
1. a4 b6 2. a5 Lb7 3. a6 Dc8 4. axb7 Sa6 5. b8=L Db7 6. f3 Dc6 7. f4 Dc3 8. dxc3 Kd8 9. Le3 Kc8 10. Lc5 Kb7 11. Lb4 Kc6 12. La5 bxa5 13. e3 Kb6 14. Lb5 Kb7 15. Se2 Kc8 16. Tf1 Kd8 17. Tf3 Ke8 18. Dxd7#
play all play one stop play next play all
D. Meinking: Comm., USPB 1995-1997 (2002-7-6)
comment
Keywords: Unique Proof Game, Promenade (K), Loss of tempo (Bk9)
Genre: Retro
Input: Gerd Wilts, 1996-8-12
Last update: Gerd Wilts, 2005-12-29 more...
2 - P0007040
Noam D. Elkies
3407 U.S. Problem Bulletin 102/103 07-10/1995
P0007040
(16+16) C+
BP in 14,0
1. h4 f6 2. Th3 Kf7 3. Te3 Kg6 4. Te6 Kf5 5. e4+ Kf4 6. Dh5 Sc6 7. De5+ Kg4 8. Se2 Sd4 9. Sec3 Sf5 10. Ke2 Kh5 11. Kf3 Kg6 12. Kg4 Kf7 13. Kh5 Ke8 14. g4 g6#
play all play one stop play next play all
Keywords: Unique Proof Game, Loss of tempo (k9), Capture-free
Genre: Retro
Computer test: Resolution time : 7.31 s., Natch 2.3 Copyright (C) 1997,98,99,2001,2002,2003,2004 Pascal Wassong
Input: Gerd Wilts, 1996-8-12
Last update: A.Buchanan, 2014-5-23 more...
3 - P0007041
Noam D. Elkies
3408 U.S. Problem Bulletin 102/103 07-10/1995
P0007041
(16+16)
BP in 16,0
1. c3 g5 2. Da4 g4 3. Df4 d5 4. h3 d4 5. Dh2 g3 6. Kd1 Lg4 7. Kc2 e6 8. Kd3 Lb4 9. Ke4 c5 10. Ke5 Sc6+ 11. Kf4 Df6+ 12. Ke4 Sge7 13. Kd3 0-0 14. Kc2 Kh8 15. Kd1 Tg8 16. Ke1 Taf8
play all play one stop play next play all
Keywords: Unique Proof Game, Castling, Loss of tempo (K11), Capture-free
Genre: Retro
Input: Gerd Wilts, 1996-8-12
Last update: A.Buchanan, 2014-5-23 more...
4 - P0008138
Noam D. Elkies
Retros mailing list 05/1996
P0008138
(16+16) C+
BP in 5,0
1. e3 e5 2. Ke2 Bb4 3. Kf3 Ke7 4. Kg4 h5+ 5. Kg5 Ke6#
play all play one stop play next play all
Keywords: Unique Proof Game, Capture-free
Genre: Retro
Input: Gerd Wilts, 1996-9-7
Last update: A.Buchanan, 2014-5-23 more...
5 - P0008141
Gianni Donati
Noam D. Elkies
Göran Forslund

Retros mailing list 05/1996
P0008141
(16+16) C+
BP in 3,0
1. f3 e5 2. Kf2 Dh4+ 3. Ke3 Dd4#
play all play one stop play next play all
Keywords: Unique Proof Game, Capture-free
Genre: Retro
Input: Gerd Wilts, 1996-9-7
Last update: A.Buchanan, 2014-5-23 more...
6 - P0008147
Richard Stanley
Noam D. Elkies

Retros mailing list 05/1996
P0008147
(15+16) C+
BP in 4,0
1. c4 Sa6 2. c5 Sxc5 3. e3 a6 4. Se2 Sd3#
play all play one stop play next play all
Keywords: Unique Proof Game
Genre: Retro
Input: Gerd Wilts, 1996-9-7
Last update: Gerd Wilts, 2004-8-11 more...
7 - P0008150
Noam D. Elkies
Retros mailing list 05/1996
P0008150
(16+16) C+
BP in 5,0
1. e3 e6 2. Ke2 e5 3. Kf3 e4+ 4. Kg4 d5+ 5. Kh5 g6#
play all play one stop play next play all
Keywords: Unique Proof Game, Capture-free
Genre: Retro
Input: Gerd Wilts, 1996-9-7
Last update: A.Buchanan, 2014-5-23 more...
8 - P0008154
Noam D. Elkies
Retros mailing list 05/1996
P0008154
(16+14) C+
BP in 5,5
1. d4 h5 2. d5 Th6 3. d6 Te6 4. dxe7 f6 5. Dxd7 Kf7 6. e8=D#
play all play one stop play next play all
Keywords: Unique Proof Game, Promotion
Genre: Retro
Input: Gerd Wilts, 1996-9-7
Last update: Gerd Wilts, 2004-8-11 more...
9 - P0008161
Noam D. Elkies
Retros mailing list 05/1996
P0008161
(16+14) C+
BP in 5,5
1. d4 h5 2. d5 Th6 3. d6 Te6 4. dxe7 f6 5. Dxd7 Kf7 6. e8=L#
play all play one stop play next play all
Keywords: Unique Proof Game, Promotion
Genre: Retro
Input: Gerd Wilts, 1996-9-7
Last update: Gerd Wilts, 2004-8-11 more...
10 - P0008167
Noam D. Elkies
Retros mailing list 05/1996
P0008167
(16+15) C+
BP in 5,0
1. d3 Sf6 2. Lf4 Se4 3. Lxc7 Sd2 4. Ld6 Da5 5. Lc5 Sf3#
play all play one stop play next play all
Keywords: Unique Proof Game
Genre: Retro
Input: Gerd Wilts, 1996-9-7
Last update: Gerd Wilts, 2004-8-11 more...
11 - P0008168
Noam D. Elkies
Retros mailing list 06/1996
P0008168
(15+15) C+
BP in 5,0
1. Sc3 Sf6 2. Sd5 Se4 3. Sxe7 Sxd2 4. Sd5 Lb4 5.a3 Sf3#
play all play one stop play next play all
Keywords: Unique Proof Game
Genre: Retro
Input: Gerd Wilts, 1996-9-7
Last update: Gerd Wilts, 2004-8-11 more...
12 - P0008203
Noam D. Elkies
3229 U.S. Problem Bulletin 99/100 01-04/1995
P0008203
(16+13)
BP in 19,5
1. Sc3 c6 2. Se4 Dc7 3. Sg5 Dg3 4. hxg3 Kd8 5. Th4 Kc7 6. Tb4 Kd6 7. e4 Ke5 8. Lb5 Kf6 9. d3 Kg6 10. Le3 Kh6 11. Dd2 Kh5 12. Kf1 Kg6 13. Te1 Kf6 14. Dd1 Ke5 15. Ld4+ Kd6 16. Te3 Kc7 17. Tf3 Kd8 18. Tf6 Ke8 19. Txc6 d6 20. Txc8+
play all play one stop play next play all
Keywords: Unique Proof Game, Loss of tempo (k15)
Genre: Retro
Reprints: U.S. Problem Bulletin 102/103 07-10/1995
Input: Gerd Wilts, 1996-9-11
Last update: Gerd Wilts, 2005-12-29 more...
13 - P0008788
Noam D. Elkies
FIDE Kongress 39 Tel Aviv 1996
1. Preis
P0008788
(12+16)
BP in 23,0
1. c3 c6 2. Db3 Db6 3. Kd1 Dxf2 4. Db6 axb6 5. h4 Ta3 6. Th3 Tb3 7. a4 Ta3 8. Tg3 Ta2 9. Tg6 hxg6 10. Sh3 Th5 11. Sf4 Tb5 12. h5 Tb3 13. h6 Tba3 14. b3 Tb2 15. h7 Ta2 16. Sa3 Tb1 17. h8=T Tab2 18. Ta2 Ta1 19. Th3 Tb1 20. Tc2 Tb2 21. Sb1 Tba2 22. La3 Tb2 23. Tg3 Dxf1#
play all play one stop play next play all
Keywords: Unique Proof Game
Genre: Retro
Input: Gerd Wilts, 1997-6-21
Last update: Gerd Wilts, 2006-1-12 more...
14 - P0542878
Noam D. Elkies
508 Variantim 08/1995
P0542878
(2+2) C+
h#7
0.2.1...
1) 1. ... Kh2 2. Sd5 Kh3 3. Sf4+ Kh4 4. Sh3 Sd1 5. Kg2 Kg4 6. Kh1 Kg3 7. Sg1 Sf2#
2) 1. ... Kg1 2. Sc4 Kf1 3. Sd2+ Ke1 4. Sf1 Sf5 5. Kg2 Ke2 6. Kh1 Kf2 7. Sh2 Sg3#
play all play one stop play next play all
Olaf Jenkner: gespiegelt nochmal 1996 in der Schwalbe veröffentlicht (P1083816) (2010-5-9)
comment

Genre: h#
Computer test: (Popeye C-Version 3.52 (2048 KB))
Input: hpr, 1998-4-18
Last update: hpr, 1999-10-20 more...
15 - P0543062
Noam D. Elkies
546 Variantim 21 11/1995
P0543062
(2+2) C+
h#8
1. Kb7 Sc6 2. Ka6 Ka2 3. Kb5 Kb2 4. Kc4+ Ka3 5. Kc3 Ka4 6. Kb2 Sd4 7. Ka1 Ka3 8. Tb1 Sc2#
play all play one stop play next play all
Vorgänger: Mertes, feenschach 1977,Scheglow, Problemist Pribuzhja 30.09.1992
comment
Keywords: anticipated
Genre: h#
Computer test: (Popeye C-Version 3.52 (2048 KB))
Input: hpr, 1998-4-19
Last update: Olaf Jenkner, 2010-5-9 more...
16 - P1000572
Noam D. Elkies
7409 Thema Danicum 91 07/1998
New Years TT
P1000572
(14+11) C+
BP in 6,5
2 Varianten
1. d4 e5 2. dxe5 Ld6 3. exd6 Sc6 4. dxc7 Sd4 5. cxd8=L Sxe2 6. Ldg5 Sxc1 7. Lxc1
1. d4 Sc6 2. Lg5 Sxd4 3. Lxe7 Sxe2 4. Lxd8 Ld6 5. Lxc7 Lf4 6. Lxf4 Sc1 7. Lxc1
play all play one stop play next play all
Keywords: Unique Proof Game (2), Homebase (2), Pronkin Theme (L)
Genre: Retro
Computer test: (Popeye C-Version 3.54 (2048 KB))
Input: Gerd Wilts, 2000-8-1
Last update: A.Buchanan, 2013-2-3 more...
17 - P1000586
Noam D. Elkies
7423 Thema Danicum 91 07/1998
New Years TT
P1000586
(15+15) C+
BP in 9,5
1. Sf3 f6 2. Sd4 f5 3. Sb5 f4 4. d4 f3 5. Le3 fxe2 6. Kd2 e1=S 7. Lc4 Sd3 8. Sc3 Se5 9. Dh5 Sf7 10. Lxf7
play all play one stop play next play all
Keywords: Ceriani-Frolkin Theme (s), Unique Proof Game, Homebase (S), Loss of tempo
Genre: Retro
Computer test: (Natch 1.3 Copyright (C) 1997-1999 Pascal Wassong)
Input: Gerd Wilts, 2000-8-1
Last update: A.Buchanan, 2013-1-19 more...
18 - P1001039
Noam D. Elkies
5 Retros mailing list 24/01/2001
P1001039
(7+3+1)
Welche Farbe hat der Ba6 und welches war der letzte Zug?

Schwarz wird auf jeden Fall Patt, d.h. die Stellung ist remis. Der letzte Zug muß Lc8-b7+, der Ba6 ist weiß. Nur dann hatte Schwarz eine Wahl bei seinem letzten Zug, d.h. nur dann war überhaupt ein legaler Zug möglich.
Keywords: Dead Position, Last Move?, Type C
Genre: Retro
Reprints: www.herderschach.de
www.schachfieber.de 2009/12/16
Input: Gerd Wilts, 2001-1-25
Last update: A.Buchanan, 2018-2-22 more...
19 - P1001042
Andrew Buchanan
Noam D. Elkies

8v Retros mailing list 24/01/2001
P1001042
(12+1)
Last move?
R: 1. Kf1xSe1
play all play one stop play next play all
Without A1.3, the last move candidates avoiding retropat or retrocage are R: 1. Kf1*Xe1 (X=D,T,S) & 1. Lh2*Xg1 (X=D,T), However if X=D,T the move would have been forced, so under A1.3 would have terminated the game. So R: 1. Kf1xSe1 was the last move.
Objective: Type A Last move. Removal of weasels Bg1 & Ph3 yields most economical known A1.3 Type A composition. This is much less economical than a non-DR approach to Type A. In general, A1.3 is much more effective for Type B & Type C than for Type A.
more ...
comment
Keywords: Dead Position, Last Move?, Rex solus (S), Type A
Genre: Retro
Input: Gerd Wilts, 2001-1-25
Last update: A.Buchanan, 2018-10-15 more...
20 - P1001169
Noam D. Elkies
(6) Probleemblad 06/2000
P1001169
(16+10) C+
BP in 6,5
1. e4 a6 2. Lxa6 d5 3. Lxb7 Ta6 4. Lxd5 Lb7 5. Lxb7 Dd3 6. Lxa6 Df1 7. Lxf1
play all play one stop play next play all
Keywords: Unique Proof Game, Round Trip (L)
Genre: Retro
Computer test: (Natch 1.3 Copyright (C) 1997-1999 Pascal Wassong)
Reprints: (6) Schweizerische Schachzeitung 05/2005
Input: Gerd Wilts, 2001-2-11
Last update: Gerd Wilts, 2006-7-28 more...
21 - P1001171
Noam D. Elkies
(8) Probleemblad 06/2000
P1001171
(12+14) C+
BP in 7,0
1. e4 Sf6 2. Dh5 Sxe4 3. Dxh7 Sc3 4. Dh5 Sxa2 5. Dd1 Sxc1 6. Dxc1 Txh2 7. Dd1 Th8
play all play one stop play next play all
Keywords: Unique Proof Game, Switchback (D3 t), Homebase (2)
Genre: Retro
Computer test: (Natch 1.3 Copyright (C) 1997-1999 Pascal Wassong)
Input: Gerd Wilts, 2001-2-11
Last update: A.Buchanan, 2017-9-29 more...
22 - P1001174
Noam D. Elkies
(11) Probleemblad 06/2000
P1001174
(16+13) C+
BP in 5,5
1. d4 h5 2. Dd2 Th6 3. Dxh6 Sa6 4. Db6 Sb8 5. Dxa7 b6 6. Dxb8
play all play one stop play next play all
Keywords: Unique Proof Game
Genre: Retro
Computer test: (Natch 1.3 Copyright (C) 1997-1999 Pascal Wassong)
Input: Gerd Wilts, 2001-2-11
Last update: Gerd Wilts, 2005-7-16 more...
23 - P1001278
Noam D. Elkies
Retros mailing list 1997
2. Preis Retro List Quick Composition Tourney
P1001278
(16+13) C+
BP in 14,5
1. b3 c6 2. Lb2 Da5 3. Ld4 Dc3 4. dxc3 Kd8 5. Kd2 Kc7 6. Kd3 Kd6 7. Kc4 Ke6 8. Kc5 a6 9. Kb6 Ta7 10. Kxa7 Kd5 11. Ka8 Kd6 12. Lc5+ Kc7 13. Dd6+ Kd8 14. Dc7+ Ke8 15. Dxc8+
play all play one stop play next play all
Keywords: Unique Proof Game
Genre: Retro
Computer test: (Natch 1.3 Copyright (C) 1997-1999 Pascal Wassong)
Reprints: feenschach 137 08-09/2000
Input: Gerd Wilts, 2001-9-2
Last update: Gerd Wilts, 2005-12-24 more...
24 - P1003061
Ofer Comay
Noam D. Elkies
Richard Stanley

H0580 StrateGems 10-12/2001
P1003061
(2+13) C+
h#5
1. Te4+ d4 2. Le5+ dxe5 3. Db6+ e6 4. Dd8+ e7 5. Df8+ exf8=S#
play all play one stop play next play all

Genre: h#
Computer test: (Popeye WINDOWS-32Bit-Version 3.73 (2048 KB))
Input: hpr, 2002-3-3
Last update: hpr, 2002-3-3 more...
25 - P1004002
Noam D. Elkies
R0094 StrateGems 17 01-03/2002
Richard Stanley gewidmet
P1004002
(14+15)
BP in 23,5
1. Sc3 d5 2. Sxd5 h6 3. Se3 Dd3 4. Tb1 Dh7 5. Sf5 a5 6. e3 a4 7. Dh5 a3 8. Ke2 axb2 9. a4 Ta6 10. a5 Tg6 11. a6 c5 12. a7 c4 13. a8=T c3 14. Ta6 cxd2 15. Tb6 d1=T 16. Ld2 Sf6 17. La5 Td8 18. c3 Sd7 19. Kd3 Dg8 20. Kd4 Th7 21. Lb5 Dh8 22. La4 Sg8 23. Kd5 f6 24. Ke6= patt
play all play one stop play next play all
Keywords: Unique Proof Game
Genre: Retro
Input: Gerd Wilts, 2002-4-5
Last update: A.Buchanan, 2014-6-16 more...
26 - P1004231
Noam D. Elkies
PCCC Meeting 08/2001
P1004231
(16+10)
BP in 22,5
Keine Doppelbauern!
1. a4 e5 2. Ta3 Lc5 3. Th3 Le3 4. Th5 c5 5. h4 Da5 6. Th3 Dc3 7. Tg3 a5 8. Txg7 Ta6 9. g4 Tf6 10. g5 Tf3 11. g6 f6 12. Te7+ Kd8 13. g7 Sh6 14. g8=L d6 15. Ld5 Tg8 16. Lg2 Tgg3 17. fxg3 Lf5 18. exf3 Sd7 19. Ke2 Kc7 20. dxe3 Ld3+ 21. cxd3 Kb6 22. Dc2 Kb5 23. bxc3+
play all play one stop play next play all
Keywords: Unique Proof Game
Genre: Retro
Reprints: Die Schwalbe 191 10/2001
Input: Gerd Wilts, 2002-10-19
Last update: A.Buchanan, 2014-5-23 more...
27 - P1004448
Noam D. Elkies
Retros mailing list 12/01/2003
P1004448
(15+14) C+
BP in 6,5
1. d4 d5 2. Lf4 Lf5 3. e3 e6 4. Dh5 Dh4 5. Sf3 Dxf2 6. Kxf2 Sf6 7. Dxf7
play all play one stop play next play all
f-Linie ist vollständig von Figuren besetzt.
comment
Keywords: Unique Proof Game
Genre: Retro
Computer test: (Natch 2.1 Copyright (C) 1997,98,99,2001,2002 Pascal Wassong)
Input: Gerd Wilts, 2003-2-1
Last update: Gerd Wilts, 2003-2-2 more...
28 - P1004449
Noam D. Elkies
Retros mailing list 12/01/2003
P1004449
(14+14) C+
BP in 8,5
1. d4 c5 2. Le3 cxd4 3. Lxd4 d5 4. e3 Le6 5. Lc4 Kd7 6. Lxd5 Lxd5 7. Dd3 e6 8. Sd2 Ld6 9. Td1
play all play one stop play next play all
d-Linie vollständig mit Figuren besetzt.
comment
Keywords: Unique Proof Game
Genre: Retro
Computer test: (Natch 2.1 Copyright (C) 1997,98,99,2001,2002 Pascal Wassong)
Input: Gerd Wilts, 2003-2-1
Last update: Gerd Wilts, 2003-2-2 more...
29 - P1004450
Noam D. Elkies
Retros mailing list 12/01/2003
P1004450
(15+15) C+
BP in 8,0
1. d3 d6 2. Le3 Le6 3. Lxa7 Lxa2 4. c4 c5 5. Da4 Sc6 6. Da6 Da5 7. Sc3 Da3 8. Sa4 Sa5
play all play one stop play next play all
a-Linie vollständig mit Figuren besetzt.
comment
Keywords: Unique Proof Game
Genre: Retro
Computer test: (Natch 2.1 Copyright (C) 1997,98,99,2001,2002 Pascal Wassong)
Input: Gerd Wilts, 2003-2-1
Last update: Gerd Wilts, 2003-2-2 more...
30 - P1004451
Noam D. Elkies
Retros mailing list 12/01/2003
P1004451
(15+15) C+
BP in 8,0
1. g3 g6 2. Lg2 Lg7 3. Lxb7 Lxb2 4. d4 d5 5. Ld2 Ld7 6. Lb4 Lb5 7. c3 c6 8. Db3 Db6
play all play one stop play next play all
b-Linie ist vollständig von Figuren besetzt.
comment
Keywords: Unique Proof Game
Genre: Retro
Computer test: (Natch 2.1 Copyright (C) 1997,98,99,2001,2002 Pascal Wassong)
Input: Gerd Wilts, 2003-2-1
Last update: Gerd Wilts, 2003-2-2 more...
31 - P1004452
Noam D. Elkies
Retros mailing list 12/01/2003
P1004452
(15+13) C+
BP in 8,0
1. d4 e5 2. Kd2 Ke7 3. Kc3 Kd6 4. dxe5 Kc5 5. Dxd7 Sc6 6. Dxc7 Dd1 7. e3 Ld6 8. Lc4 Dxc2
play all play one stop play next play all
c-Linie ist vollständig von Figuren besetzt.
comment
Keywords: Unique Proof Game
Genre: Retro
Computer test: (Natch 2.1 Copyright (C) 1997,98,99,2001,2002 Pascal Wassong)
Input: Gerd Wilts, 2003-2-1
Last update: Gerd Wilts, 2003-2-2 more...
32 - P1004453
Noam D. Elkies
Retros mailing list 12/01/2003
P1004453
(15+15) C+
BP in 8,0
1. Sc3 Sc6 2. Se4 Se5 3. c3 c6 4. Db3 Db6 5. De6 De3 6. b3 b6 7. La3 La6 8. Lxe7 Lxe2
play all play one stop play next play all
e-Linie ist vollständig von Figuren besetzt.
comment
Keywords: Unique Proof Game
Genre: Retro
Computer test: (Natch 2.1 Copyright (C) 1997,98,99,2001,2002 Pascal Wassong)
Input: Gerd Wilts, 2003-2-1
Last update: Gerd Wilts, 2003-2-2 more...
33 - P1004454
Noam D. Elkies
Retros mailing list 12/01/2003
P1004454
(15+15) C+
BP in 8,0
1. b3 b6 2. Lb2 Lb7 3. Lxg7 Lxg2 4. e4 e5 5. Dg4 Dg5 6. f3 f6 7. Kf2 Kf7 8. Kg3 Kg6
play all play one stop play next play all
g-Linie ist vollständig von Figuren besetzt.
comment
Keywords: Unique Proof Game
Genre: Retro
Computer test: (Natch 2.1 Copyright (C) 1997,98,99,2001,2002 Pascal Wassong)
Input: Gerd Wilts, 2003-2-1
Last update: Gerd Wilts, 2003-2-2 more...
34 - P1004455
Noam D. Elkies
Retros mailing list 12/01/2003
P1004455
(15+15) C+
BP in 8,0
1. c3 c6 2. Dc2 Dc7 3. Dxh7 Dxh2 4. d3 d6 5. Lh6 Lh3 6. e3 e6 7. Le2 Le7 8. Lh5 Lh4
play all play one stop play next play all
h-Linie ist vollständig von Figuren besetzt.
comment
Keywords: Unique Proof Game
Genre: Retro
Computer test: (Natch 2.1 Copyright (C) 1997,98,99,2001,2002 Pascal Wassong)
Input: Gerd Wilts, 2003-2-1
Last update: Gerd Wilts, 2003-2-2 more...
35 - P1004462
Noam D. Elkies
Retros mailing list 28/01/2003
P1004462
(15+15) C+
BP in 7,5
1. e4 a6 2. Lxa6 c5 3. d3 Da5+ 4. Ld2 Dxa2 5. La5 Da4 6. Sa3 Sc6 7. Db1 Sa7 8. Da2
play all play one stop play next play all
Keywords: Unique Proof Game
Genre: Retro
Computer test: (Popeye C-Version 3.54 (30 KB))
Input: Gerd Wilts, 2003-2-1
Last update: Gerd Wilts, 2004-11-13 more...
36 - P1011909
Noam D. Elkies
Retros mailing list 31/12/2003
Lob
Gianni Donati 50th Jubilee Tourney
P1011909
(16+14) C+
BP in 9,0
1. f4 Sf6 2. f5 Se4 3. f6 c5 4. fxg7 Db6 5. g8=L Dg6 6. Lxh7 Sc6 7. Lg8 Th3 8. Lh7 Ta3 9. Lg8 Ta4
The promoted wB is the only unit that can move while the bR travels h8-h3-a3-a4. This rook path is not immediately obvious, giving the problem a bit of zest. (PR Gianni Donati)
play all play one stop play next play all
Keywords: Unique Proof Game, Round Trip
Genre: Retro
Computer test: Euclide 0.92, c2000-2002 Étienne Dupuis
Input: Gerd Wilts, 2004-1-1
Last update: Gerd Wilts, 2004-1-1 more...
37 - P1011914
Noam D. Elkies
Retros mailing list 31/12/2003
Lob
Gianni Donati 50th Jubilee Tourney
P1011914
(15+12) C+
BP in 14,0
1. f4 e5 2. f5 Dg5 3. f6 Lc5 4. fxg7 Sf6 5. g8=S d6 6. Sh6 Le6 7. Sxf7 0-0 8. Sh8 Sbd7 9. Sg6 Tae8 10. Sxf8 Te7 11. Sxh7 Se8 12. Sf6+ Kh8 13. Sg8 Lxg8 14. g4 Dh4#
play all play one stop play next play all
Keywords: Ceriani-Frolkin Theme (S), Unique Proof Game, Round Trip
Genre: Retro
Input: Gerd Wilts, 2004-1-1
Last update: Gerd Wilts, 2004-8-25 more...
38 - P1013043
Noam D. Elkies
6 The Electronic Journal of Combinatorics vol.11(2) 2004
P1013043
(16+0)
Serienzug-BP in 12
Wieviele Lösungen?

2004 Lösungen!
Problem 6: N.D.Elkies, New Directions in Enumerative Chess Problems, The Electronic Journal of Combinatorics, vol. 11(2), 2004.

2004 = C(12,1) * (C(11,3) + 2)
comment
Keywords: Non-Unique Proof Game, Path enumeration (year), Series mover
Genre: Retro, Mathematics, Fairies
Reprints: Retros mailing list 10/01/2004
Input: Gerd Wilts, 2004-1-24
Last update: A.Buchanan, 2017-9-22 more...
39 - P1015559
Noam D. Elkies
2069 U.S. Problem Bulletin 09-10/1990
Spezielle ehrende Erwähnung
P1015559
(3+3) C+
s#9
1. Dg1 h3 2. Le4 Kh4 3. Dg6 h5 4. Lg2 hxg2 5. Kg1 Kh3 6. Dg5 h4 7. Dh5 Kg3 8. Df5 h3 9. De4 h2#
play all play one stop play next play all
more ...
comment
Keywords: Asymmetrical solution, Oneliner
Genre: s#
Computer test: I. Soroka: Gustav 3.1 t
Reprints: 1097 Selbstmatt-Miniaturen Reflexmatt-Miniaturen 2003
Input: Selbstmatt-Miniaturen/Reflexmatt-Miniaturen, 2004-5-1
Last update: Olaf Jenkner, 2010-12-13 more...
40 - P1015665
Noam D. Elkies
PS990 The Problemist Supplement 45 03/2000
P1015665
(3+3) C+
s#8
1. Lb1 Kd1 2. Db2 Ke1 3. Dc2 Kf1 4. De4 Kf2 5. Ld3 Kg3 6. Dd4 Kf3 7. Lf1 Kg3 8. Lg2 hxg2#
play all play one stop play next play all
Antikritischer Schlüssel, Bahnung, Rückkehr. Königslenkung ohne Schachgebot.
Keywords: Königslenkung, white Bristol (DL), Round Trip
Genre: s#
Reprints: 1204 Selbstmatt-Miniaturen Reflexmatt-Miniaturen 2003
Input: Selbstmatt-Miniaturen/Reflexmatt-Miniaturen, 2004-5-1
Last update: Alfred Pfeiffer, 2015-7-20 more...
41 - P1018888
Noam D. Elkies
The Problemist Supplement 1998
P1018888
(6+3)
#3

BS Problemid: 3725
Authors: Elkies, Noam D
Sources:
Years: 1998
Keywords: Brian Stephenson Collection (3725)
Genre: 3#
Input: Brian Stephenson, 2004-8-12
42 - P1066725
Noam D. Elkies
feenschach 154 2004
2. Preis Champagne TT 2004
P1066725
(10+15) C+
BP in 19,0
1. h4 b5 2. Th3 b4 3. Ta3 b3 4. c3 bxa2 5. Db3 g5 6. Kd1 g4 7. Kc2 g3 8. Kd3 axb1=D+ 9. Ke3 Dxc1 10. Sf3 Dxf1 11. Se5 Dh1 12. Kf3 Dh3 13. Th1 d6 14. Taa1 Lf5 15. Tag1 Lb1 16. Th2 f5 17. Dxg8 gxh2+ 18. Dg3 Lh6 19. Sf7 hxg1=S#
play all play one stop play next play all
Richter MC: "The manoever Qb1-h1-h3 cleanly forces the exchange of place. This is the only example where the exchange is effective (position after 14th white move). Interestingly, the Rooks are not captured on the sibling squares with an « almost circuit » by Rh1."
Keywords: Unique Proof Game, Non-standard material, Interchange (TT)
Genre: Retro
Reprints: PCCC Meeting 09/2004
H51 Phénix 02-03/2005
Input: Gerd Wilts, 2004-9-14
Last update: Gerd Wilts, 2005-11-24 more...
43 - P1066792
Noam D. Elkies
Retros mailing list 1993
P1066792
(6+8)
Wer gewinn?
1. fxg6ep#
play all play one stop play next play all
Keywords: En passant as key
Genre: Retro
Reprints: Retros mailing list 08/10/2004
Input: Gerd Wilts, 2004-10-17
Last update: Gerd Wilts, 2004-10-17 more...
44 - P1068208
Noam D. Elkies
Retros mailing list 01/01/2006
P1068208
(16+16)
BP in 7,5
Wieviele Lösungen?

2006 Lösungen!
2006 = (C(8,3) + 3) * (C,7,3) - 1)
comment
Keywords: Non-Unique Proof Game, Path enumeration (year), Capture-free
Genre: Retro, Mathematics
Input: Gerd Wilts, 2006-1-7
Last update: A.Buchanan, 2017-8-30 more...
45 - P1068209
Noam D. Elkies
Retros mailing list 01/01/2006
P1068209
(16+0)
Serienzug-BP in 14
Wieviele Lösungen?

2006 Lösungen!
2006 = 2 * (C(14,4) + 2)
comment
Keywords: Non-Unique Proof Game, Series mover, Path enumeration (year)
Genre: Mathematics, Retro, Fairies
Input: Gerd Wilts, 2006-1-7
Last update: A.Buchanan, 2017-9-22 more...
46 - P1069068
Noam D. Elkies
Retros mailing list 24/12/2006
P1069068
(16+0)
Serienzug-BP in 12
Wieviele Lösungen?

2007 Lösungen!
2007 = C(3,1) * C(3,1) * (C(12,3) + 1)
comment
Keywords: Series mover, Non-Unique Proof Game, Path enumeration (year)
Genre: Retro, Mathematics, Fairies
Input: Gerd Wilts, 2006-12-31
Last update: A.Buchanan, 2017-9-22 more...
47 - P1070032
Noam D. Elkies
R0142 StrateGems 41 01-03/2008
P1070032
(11+2)
What result?
hans: draw by stalemate (bK can't get in over a-b-line, so 1. 0-0# is illegal) (2014-9-17)
comment
Keywords: Castling
Genre: Retro
Input: Gerd Wilts, 2008-9-8
Last update: Gerd Wilts, 2008-9-8 more...
48 - P1070033
Thomas Volet
Noam D. Elkies

R0143 StrateGems 41 01-03/2008
Lob
P1070033
(11+3)
a) What result?
b) [DR] Whose move?

(a) Draw. If BTM, it's pat already (1. axb3ep impossible since wBa1+wPa2 is illegal). If WTM it's dead already, (1. cxb6ep impossible since wBa8 would be promoted, which implies 14 White pawn captures - 1 too many) and White has no way to give Black a move.
(b) If WTM, last move was c6xb5, forced into dead position. Hence by A1.3 the game was already over before. So BTM.
Keywords: En passant, Dead Position, Whose move?
Genre: Retro
Input: Gerd Wilts, 2008-9-8
Last update: A.Buchanan, 2017-8-28 more...
49 - P1083816
Noam D. Elkies
Die Schwalbe 1996
P1083816
(2+2) C+
h#7
0.2.1...
1) 1. ... Ka2 2. Se5 Ka3 3. Sc4+ Ka4 4. Sa3 Se1 5. Kb2 Kb4 6. Ka1 Kb3 7. Sb1 Sc2#
2) 1. ... Kb1 2. Sf4 Kc1 3. Se2+ Kd1 4. Sc1 Sc5 5. Kb2 Kd2 6. Ka1 Kc2 7. Sa2 Sb3#
play all play one stop play next play all
Olaf Jenkner: gespiegeltes Eigenplagiat von P0542878 (2010-5-9)
Mario Richter: Kein Eigenplagiat, sondern abgedruckt innerhalb eines Berichts über das 39.PCCC-Treffen in Tel Aviv; das Diagramm stammt aus dem dort gehaltenen Vortrag von N.Elkies "Composing (?) by Computer". (s. Schwalbe Heft 162, S.521ff) (2010-5-9)
paul: The earliest K+S vs K+S that I know is P0542769 (2010-5-24)
Olaf Jenkner: Vielleicht sollte diese Aufgage gelöscht werden und die spätere Spiegelung als Kommentar zur ursprünglichen Aufgabe angemerkt werden. (2010-5-25)
comment
Keywords: anticipated
Genre: h#
Computer test: Popeye Windows-32Bit v4.47 (100000 KB)
Reprints: 2295 Ideal-Mate Encyclopedia Vol.2 2000
Input: hpr, 2009-3-13
Last update: Olaf Jenkner, 2010-5-9 more...
50 - P1167010
Noam D. Elkies
StrateGems 2001
P1167010
(4+1)
#3
1. Sg1 Kxg1 2. h8=D Kf1 3. Da1#
play all play one stop play next play all
KRS
comment
Keywords: Miniature Collection (0347917)
Genre: 3#
Input: Zuncke/Bruder, 2010-9-12
Last update: Zuncke/Bruder, 2010-9-12 more...
51 - P1181650
Noam D. Elkies
Website Tim Krabbé (334) 04/01/2007
nach H.H.Cross
P1181650
(14+8)
White to play
Worst possible move, n=28
Schlechtmöglichster Zug: 1. Dxc5+ Sxc5#
play all play one stop play next play all
Weiß hat insgesamt 28 Züge, 27 davon setzen matt, 1 Zug erzwingt Selbstmatt
vgl. P1178654 (H.H.Cross)
Keywords: Einzügerrekord
Genre: Fairies
Input: HBae, 2010-12-4
Last update: HBae, 2010-12-4 more...
52 - P1181655
Noam D. Elkies
Website Tim Krabbé (334) 08/01/2007
P1181655
(15+6)
40 erzwungene Mattzüge mit Umwandlungsfiguren

Schon früher überboten:
P1181005 (Zagler, 47) ohne Batterien
P1181648 (Dittmann, 50)
P1178655 (Zagler, 55)
Keywords: Einzügerrekord (A1d4), Promoted material on the board
Genre: Fairies
Input: HBae, 2010-12-4
Last update: HBae, 2010-12-4 more...
53 - P1181656
Noam D. Elkies
Website Tim Krabbé (334) 10/01/2007
P1181656
(16+8)
43 erzwungene Mattzüge mit Umwandlungsfiguren und Umwandlungszügen

Schon früher überboten:
P1181005 (Zagler, 47) ohne Batterien
P1181648 (Dittmann, 50)
P1178655 (Zagler, 55)
Keywords: Einzügerrekord (A1e4), Promotion, Promoted material on the board
Genre: Fairies
Input: HBae, 2010-12-4
Last update: HBae, 2010-12-4 more...
54 - P1181657
Noam D. Elkies
Website Tim Krabbé (334) 10/01/2007
P1181657
(15+8)
White to play
Worst possible move, n=41 (legal position, promoted men, promotion moves)
Schlechtmöglichster Zug: 1. Df5+ Sxf5#
play all play one stop play next play all
Weiß hat insgesamt 41 Züge, 40 davon setzen matt, 1 Zug erzwingt Selbstmatt
Keywords: Einzügerrekord, Promoted material on the board
Genre: Fairies
Input: HBae, 2010-12-4
Last update: HBae, 2010-12-4 more...
55 - P1181665
Noam D. Elkies
Website Tim Krabbé (267) 16/11/2004
P1181665
(11+7) cooked
#7
1. a6 d5 2. Lxg4+ hxg4 3. h5 d4 4. cxd4 c3 5. d5 c2 6. d6 c1=D 7. d7#
play all play one stop play next play all
Auf der Website (Item 267) werden Beispiele für Automatismen (No-brainers) gebracht.: White has choices, but no matter what he chooses, he mates Black at move 7. This is probably the record-nobrainer without promoted pieces.
vgl. P1179363 (Lundgren, #7)
Cook: Zugumstellung 1. Lxg4+ hxg4 usw.

Genre: Fairies
Computer test: Popeye Windows-32Bit v4.55 (1575 MB)
Input: HBae, 2010-12-4
Last update: HBae, 2010-12-4 more...
56 - P1181666
Noam D. Elkies
Website Tim Krabbé (267) 16/11/2004
P1181666
(13+13)
#10
1. Ddxe5+ Ddxe5+ 2. Dcxe5+ Dcxe5+ 3. Dbxe5+ Dbxe5+ 4. Daxe5+ Dfxe5+ 5. Dfxe5+ Dgxe5+ 6. Dgxe5+ Dhxe5+ 7. Dhxe5+ Tcxe5+ 8. Txe5+ Txe5+ 9. Txe5+ Dxe5+ 10. Dxe5#
mit Zugumstellungen
play all play one stop play next play all
Automatische Zugfolge (No-brainer)
PS 23 November: Some readers wondered (I did, too) whether the position of the 10-move no-brainer is legal. It is, says Elkies: "One pawn capture on a side yields three promotable pawns (a6xb7 and c3xd2, with White promoting bbc and Black add); and two piece captures on a side give four more promoting pawns (e6xf7, g6xh7, promote ffhh; f3xe2, h3xg2, promote eegg)."
Cook: NL
1. Tf5xe5!
1. Df4xe5!
(Yuri Bilokin)
Henrik Juel: The position is indeed legal, but Noam's explanation of seven white and seven black promotions might be clarified
By 'pawn capture' he means PxP, and by 'piece capture' he means that an officer is captured by a pawn
e6xLf7 and g6xLh7 are not both possible here, as the two missing black officers have different square colors, but the latter capture could be g5xLh6 after Black has played Ph7-h5 (2018-11-2)
more ...
comment
Keywords: Aristocrat
Genre: Fairies
Input: HBae, 2010-12-4
Last update: Alfred Pfeiffer, 2018-11-5 more...
57 - P1184194
Noam D. Elkies
Retros mailing list 06/01/2011
P1184194
(16+16) C+
BP in 13,5
Wieviele Lösungen?

2011 Lösungen!
2011 = C(14,5) + C(9,1)
See also P1257468
comment
Keywords: Non-Unique Proof Game, Path enumeration (year), Capture-free
Genre: Retro, Mathematics
Computer test: Popeye 3.41
Input: Gerd Wilts, 2011-1-6
Last update: A.Buchanan, 2017-8-30 more...
58 - P1186682
Noam D. Elkies
H2742 The Problemist 01/2004
P1186682
(3+1) C+
h#7
1. Kb2 Se4 2. Kc1 c4 3. Kd1 c5 4. Ke2 c6 5. Kf3 c7 6. Kg4 c8=D+ 7. Kh4 Dh3#
play all play one stop play next play all

Genre: h#
Computer test: Popeye Windows-32Bit v4.51 (100000 KB)
Input: hpr, 2011-2-5
Last update: hpr, 2011-2-5 more...
59 - P1187767
Noam D. Elkies
H2794 The Problemist 07/2004
P1187767
(3+1) C+
h#7
1. Kg7 Lb3 2. Kf6 a4 3. Ke5 a5 4. Kd4 a6 5. Kc3 a7 6. Kb2 a8=D 7. Kb1 Da2#
play all play one stop play next play all

Genre: h#
Computer test: Popeye Windows-32Bit v4.51 (100000 KB)
Input: hpr, 2011-2-18
Last update: hpr, 2011-2-18 more...
60 - P1187769
Noam D. Elkies
H2793 The Problemist 07/2004
P1187769
(3+1) C+
h#7
1. Kg2 Sc2 2. Kf3 a4 3. Ke4 a5 4. Kd3 a6 5. Kc3 a7 6. Kb2 a8=D 7. Kb1 Da1#
play all play one stop play next play all

Genre: h#
Computer test: Popeye Windows-32Bit v4.51 (100000 KB)
Input: hpr, 2011-2-18
Last update: hpr, 2011-2-18 more...
61 - P1187774
Noam D. Elkies
H2728 The Problemist 01/2004
P1187774
(9+1)
h#10
1. Kh2 Lh1 2. Kxh1 Lbd3 3. Kh2 Lac4 4. Kh1 Lab5 5. Kh2 a4 6. Kh1 a5 7. Kh2 a6 8. Kh1 a7 9. Kh2 a8=T 10. Kh1 Th8#
play all play one stop play next play all
SBD: Haben die Loesern gesehen, das diese Problem auch ein korrektes Direktmatt in 10.5 (also ein #10 mit Schwarzem Anzug?). Als h# scheint er nicht per Computer zu pruefen wenn man nicht 2-3 Tage zum pruefen frei hat, aber Gustav hat ihn eben mit selbe Loesung oben als korrekte (C+) matt in 10,5 gegeben. (2012-1-26)
Olaf Jenkner: Gustav braucht für das h# eher 2-3 Monate. Er weiß nicht, daß der Bauer umgewandelt werden muß. (2012-1-26)
comment
Keywords: Promoted material on the board
Genre: h#
Input: hpr, 2011-2-19
Last update: Olaf Jenkner, 2012-1-26 more...
62 - P1201340
Noam D. Elkies
F0264 StrateGems 04-06/2001
P1201340
(3+2) C+
ser-s=21
Madrasi
1. g4 2. g5 3. g6 4. g7 5. g8=D 6. Dg1 7. Kb7 8. Kc6 9. Kd5 10. Kc4 11. Kc3 12. Kb2 13. Ka1 14. d4 15. Db1 16. d5 17. d6 18. d7 19. d8=T 20. Td3 21. Ta3+ Kxa3=
play all play one stop play next play all
Keywords: Series mover, corner to corner (a8a1), Excelsior (2-fach DT), Madrasi
Genre: Fairies
Computer test: Popeye WINDOWS-32Bit V4.37 (145420 KB)
Input: Frank Müller, 2011-8-26
Last update: Erich Bartel, 2016-1-29 more...
63 - P1205805
Noam D. Elkies
StrateGems 2001
P1205805
(2+2) C+
S=23, S ->
1. ... Ka5 2. Dd2 Kb5 3. Dd5 Kb4 4. Kb6 Kc3 5. Dd1 Kc4,Kb2 6. Dd2 Kb3 7. Kc5 b5 8. Kd4 b4 9. Kd3 Ka3 10. Kc2 Ka2 11. Kc1 Ka1 12. Dd4 Ka2 13. Da7 Kb3 14. Df7 Kc3 15. Dd5 b3 16. Kb1 Kb4 17. Dc6 Ka5 18. Db7 b2 19. Db3 Ka6 20. Db8 Ka5 21. Db7 Ka4 22. Db6 Ka3 23. Db3+ Kxb3=
play all play one stop play next play all

Genre: Fairies
Input: Hans Gruber, 2011-10-9
Last update: Olaf Jenkner, 2013-3-10 more...
64 - P1205823
Noam D. Elkies
Q0037 StrateGems 01-03/2001
Lob
P1205823
(2+2) C+
S=13
1. Dc5 Ka1 2. Kb3 Kb1 3. Dc2+ Ka1 4. Dc3+ Kb1 5. Dc5 Ka1 6. Kc2 Ka2 7. Dc3 c5 8. Kc1 c4 9. Da5+ Kb3 10. Kb1 c3 11. Db5 Ka3 12. Ka1 c2 13. Db3+ Kxb3=
play all play one stop play next play all

Genre: Fairies
Input: Hans Gruber, 2011-10-9
Last update: Hans Gruber, 2011-10-9 more...
65 - P1211129
Noam D. Elkies
Variant Chess 04/2009
P1211129
(3+1) C+
Schwarz am Zug, dann =44
wLU=Fers
Längstes Patt mit dem Material: 0. - Kc6 1. Kb4 Kd5 2. Kc3 Ke4 3. Kd2 Kf3 4. Ke1 Kg3 5. Kf1 Kf3 6. Fb1 Ke3 7. Ke1 Kd3 8. Fg2 Kc3 9. Kd1 Kd3 10. Fc2+ Ke3 11. Ke1 Kd4 12. Kd2 Kc4 13. Ke3 Kd5 14. Kd3 Kc5 15. Ke4 Kb4 16. Kd4 Kb5 17. Kd5 Ka5 18. Kc5 Ka6 19. Ff3 Kb7 20. Kd6 Kc8 21. Fe4 Kd8 22. Fd5 Ke8 23. Ke6 Kf8 24. Kf6 Ke8 25. Fc6 Kd8 26. Ke6 Kc7 27. Kd5 Kd8 28. Kd6 Ke8 29. Ke6 Kf8 30. Kf6 Ke8 31. Fb3 Kd8 32. Ke6 Kc7 33. Fb5 Kb7 34. F3c4 Kc8 35. Fd5 Kc7 36. Fdc6 Kd8 37. Kf7 Kc8 38. Ke8 Kc7 39. Ke7 Kc8 40. Kd6 Kb8 41. Kd7 Ka7 42. Kc7 Ka8 43. Kb6 Kb8 44. Fb7=
Auch mit wKa1, a3, a4 ist =44 möglich, nach 4. Ke1 treffen sich die Lösungen.
Teil einer computergestützten Analyse des Endspiels durch Noam Elkies.
play all play one stop play next play all

Pieces: lu = Fers (FE)
Genre: Fairies
Input: Hans Gruber, 2011-10-9
Last update: Hans Gruber, 2011-10-9 more...
66 - P1211130
Noam D. Elkies
Variant Chess 04/2009
P1211130
(3+1) C+
=41
wLU=Fers
Längstes Patt mit dem Material bei ungleichfarbigen Fersen: 1. Fd7 Kg7 2. Fc6 Kf6 3. Fb5 Ke5 4. Fa4 Kd4 5. Kd2 Kc4 6. Kc2 Kd4 7. Fg1 Ke3 8. Kd1 Kf3 9. Ke1 Ke3 10. Fb3 Kd3 11. Kd1 Ke3 12. Fc2 Kf3 13. Ke1 Ke3 14. Ff2+ Kd4 15. Kd2 Kc4 16. Ke3 Kd5 17. Fg3 Kc4 18. Ff4 Kc5 19. Fd3 Kd5 20. Fe4+ Kc4 21. Fe5 Kc5 22. Kd3 Kb5 23. Kd4 Kc6 24. Kc4 Kd7 25. Ff5 Kc6 26. Fe6 Kb6 27. Fd5 Kc7 28. Kc5 Kd7 29. Ff6 Kd8 30. Fe6 Ke8 31. Kd6 Kf8 32. Kd5 Ke8 33. Ke5 Kf8 34. Fd7 Kf7 35. Kf5 Kg8 36. Fe8 Kf8 37. Ke6 Kg8 (37. - Kxe8 38. Fe7=) 38. Ff7+ Kf8 39. Fg6 Kg8 40. Ke7 Kh8 41. Kf8=
Teil einer computergestützten Analyse des Endspiels durch Noam Elkies.
play all play one stop play next play all

Pieces: lu = Fers (FE)
Genre: Fairies
Input: Hans Gruber, 2011-10-9
Last update: Hans Gruber, 2011-10-9 more...
67 - P1211164
Noam D. Elkies
(im Text) ? 03/2009
P1211164
(2+2)
Gewinn
7x8-Brett
1. Ta2+ Kc1 2. Kc3 d1=S+
play all play one stop play next play all
Orthodox (8x8-Brett) ist das remis.
Auf dem 7x8-Brett gewinnt Weiß.
more ...
comment
Keywords: no 8x8 board
Genre: Fairies
Reprints: Variant Chess 60, p. 98, 04/2009
Input: Hans Gruber, 2011-10-9
Last update: Alfred Pfeiffer, 2015-5-15 more...
68 - P1231029
Noam D. Elkies
Variant Chess 43
Prize
P1231029
(5+4)
White to move and win.
Pawns may promote to any of the 35 leapers from L01 to L77 in addition to the usual QRBN.
1.bxa8=Q? h1=Q 2.QxQ stalemate.
1.bxa8=L02+? Kb7 2.Bxh2 Kxa8 leads to a book draw with a rook's pawn and the wrong bishop.
1.bxa8=L16 h1=Q? 2.L16g7+ wins and 1... h1=L63+ 2.Kb3 traps the L63. However 1... h1=L16! leaves the two leapers mutually trapped in what's essentially the same old draw.
So finally we turn to the least useful leaper: 1.bxa8=L77! Kb7 2.L77h1! Kxc7 and the L77's control of a8 turns out to be just enough to let white promote eventually though only by way of careful K-play and no fewer than 4 positions of mutual zugzwang: 3.Ka5! (threat 4.Ka6 Kb8 5.a5) Kb7 4.Kb5! (mutual zugzwang) a6+ 5.Kc5 (mzz) Kc7 6.a5 (mzz) Kb7 7.Kd6 Kb8 (or Ka7 8.Kc6!, avoiding 8.Kc7? stalemate) 8.Kc6 Ka7 9.a4! (final and decisive mzz) and wins.
play all play one stop play next play all
Variant Chess Theme Tourney asking for problems with the L77 leaper.
comment
Keywords: Promotion
Genre: Fairies
Input: Alain Brobecker, 2012-1-25
Last update: Alain Brobecker, 2012-1-25 more...
69 - P1243426
Noam D. Elkies
1 The Electronic Journal of Combinatorics vol.11(2) 2004
P1243426
(15+16)
How many shortest games?

Euler number, E_n, defined by generating function:
sec(x) + tan(x) = Sum(n=0...infinity) E_n (x^n/n!)
Here E_9 = 7,936.
Problem 1 original: N.D.Elkies, New Directions in Enumerative Chess Problems, The Electronic Journal of Combinatorics, vol. 11(2), 2004.
comment
Keywords: Path enumeration (Euler), Non-Unique Proof Game
Genre: Mathematics
Input: A.Buchanan, 2012-6-29
Last update: A.Buchanan, 2012-9-5 more...
70 - P1243427
Noam D. Elkies
2 The Electronic Journal of Combinatorics vol.11(2) 2004
P1243427
(16+0)
How many shortest sequences?

3850 solutions.

There is an established theory for extending a partially-ordered set to a total (linear) ordering. "The number 3850 arises as one-half the number of standard Young tableaux (SYTs) associated with the self-conjugate partition (5,3,2,1,1) of 12."
Problem 2 original: N.D.Elkies, New Directions in Enumerative Chess Problems, The Electronic Journal of Combinatorics, vol. 11(2), 2004.
A.Buchanan: This is an amusing idea. There are ten moves whose dependencies arrange themselves in an SYT *missing* two points (denoted "x):

xx...
...
..
.
.

For the full SYT including the two missing points, the top left point must be labeled 12. But 11 is either the one below 12 or the one to the left of it. *However*, since the partition is self-conjugate, by symmetry we know that exactly half of these have 11 as the label of the other x. (2012-10-7)
comment
Keywords: Non-Unique Proof Game, Series mover, Path enumeration
Genre: Mathematics, Retro, Fairies
Input: A.Buchanan, 2012-6-29
Last update: A.Buchanan, 2017-9-22 more...
71 - P1243428
Noam D. Elkies
3 The Electronic Journal of Combinatorics vol.11(2) 2004
P1243428
(6+9) C+
h#3,5. How many solutions?
1. ... cxb5 2. Txb5 b4 3. Lg8 d5 4. Da4 Kxb1#
1. ... b4 2. Da4 cxb5 3. Lg8 Kxb1 4. Txb5 d5#
play all play one stop play next play all
2 solutions only.
Problem 3 original: N.D.Elkies, New Directions in Enumerative Chess Problems, The Electronic Journal of Combinatorics, vol. 11(2), 2004.
comment
Keywords: Path enumeration
Genre: h#, Mathematics
Computer test: Popeye Windows-64Bit v4.61
Input: A.Buchanan, 2012-6-29
Last update: A.Buchanan, 2014-12-31 more...
72 - P1243429
Noam D. Elkies
7 The Electronic Journal of Combinatorics vol.11(2) 2004
P1243429
(16+0)
Serienzug-BP in 14
Wieviele Lösungen?

2005 solutions!
Problem 7 original: N.D.Elkies, New Directions in Enumerative Chess Problems, The Electronic Journal of Combinatorics, vol. 11(2), 2004.

2005 = 2 * C(14,4) + 3
comment
Keywords: Non-Unique Proof Game, Series mover, Path enumeration (year)
Genre: Mathematics, Retro, Fairies
Input: A.Buchanan, 2012-6-29
Last update: A.Buchanan, 2017-9-22 more...
73 - P1243431
Noam D. Elkies

for Richard Stanley on his 60th birthday
P1243431
(16+16)
How many shortest proof games?

Well obviously it must be 60 solutions. How does this happen? Black has taken at least 6 moves, yet White is checking him, so must have taken at least 7, although White appears to have only made 6 moves. The only way for White to lose 1 tempo is with Bc1-a3-b2. So let's aim for PG in 6.5. Black's moves are deterministic now, but White's consist of 3 independent chains: b3, Ba3, Bb2; Nf3, Nh4; Nc3. These must all be complete before the final check. 3,2 & 1 moves can be ordered in exactly 6!/(3!2!) = 60 ways.
Problem 9 original: N.D.Elkies, New Directions in Enumerative Chess Problems, The Electronic Journal of Combinatorics, vol. 11(2), 2004.
comment
Keywords: Non-Unique Proof Game, Path enumeration, Loss of tempo
Genre: Retro, Mathematics
Input: A.Buchanan, 2012-6-29
Last update: A.Buchanan, 2014-12-31 more...
74 - P1243505
Noam D. Elkies
4 The Electronic Journal of Combinatorics vol.11(2) 2004
P1243505
(10+6)
Mate in (exactly) n: how many solutions?
[Composer excludes draw by repetition & 50 move.]

F_n, the nth Fibonnaci number: 1,1,2,3,5,8,13...
Problem 4 original: N.D.Elkies, New Directions in Enumerative Chess Problems, The Electronic Journal of Combinatorics, vol. 11(2), 2004.
comment
Keywords: Path enumeration (Fibonacci), Conditional problem
Genre: Mathematics, n#
Input: A.Buchanan, 2012-6-30
Last update: A.Buchanan, 2012-9-5 more...
75 - P1243525
Noam D. Elkies
5 The Electronic Journal of Combinatorics vol.11(2) 2004
P1243525
(11+7)
Mate in (exactly) n: how many solutions?
[Composer excludes draw by repetition & 50 move.]

composer's solution: 2^F_n, where F_n is the nth Fibonacci number (1,1,2,3,5,8,13...)
Noam warns that his solution may be "controversial". Basically for fixed n, there are F_n different sequences for Black, and White is asked to find a response for each of these.
But it can be argued that White should just respond to the position, not to irrelevant history, particularly in a format in which the composer explicitly excluded draw by repetition & 50 move from consideration.
Problem 5 original: N.D.Elkies, New Directions in Enumerative Chess Problems, The Electronic Journal of Combinatorics, vol. 11(2), 2004.
comment
Keywords: Path enumeration (Fibonacci), Conditional problem
Genre: n#, Mathematics
Input: A.Buchanan, 2012-6-30
Last update: A.Buchanan, 2012-9-5 more...
76 - P1243529
Noam D. Elkies
8 The Electronic Journal of Combinatorics vol.11(2) 2004
P1243529
(16+16)
How many shortest sequences?

1,000,000 solutions
Jan 2004.
Problem 8 original: N.D.Elkies, New Directions in Enumerative Chess Problems, The Electronic Journal of Combinatorics, vol. 11(2), 2004.

NDE: "To my knowledge this is the first chess problem composed to have exactly a million solutions."
comment
Keywords: Non-Unique Proof Game, Path enumeration
Genre: Retro, Mathematics
Input: A.Buchanan, 2012-6-30
Last update: A.Buchanan, 2012-9-5 more...
77 - P1257468
Noam D. Elkies
Retros mailing list 02/01/2012
P1257468
(16+16) C+
BP in 13,5
Wieviele Lösungen?

2012 Lösungen!
2012 = C(14,5) + C(10,1)
See also P1184194
comment
Keywords: Non-Unique Proof Game, Path enumeration (year), Capture-free
Genre: Retro, Mathematics
Computer test: Popeye 3.41
Input: A.Buchanan, 2012-12-26
Last update: A.Buchanan, 2017-8-30 more...
78 - P1257469
Noam D. Elkies
Retros mailing list 04/01/2010
P1257469
(16+16) C+
BP in 12,0
Wieviele Lösungen?

2010 Lösungen!
2010 = (C(12,2)+1) * C(6,2) * 2
comment
Keywords: Non-Unique Proof Game, Path enumeration (year), Capture-free
Genre: Retro, Mathematics
Computer test: Popeye 3.41
Input: A.Buchanan, 2012-12-26
Last update: A.Buchanan, 2017-8-30 more...
79 - P1257470
Noam D. Elkies
Retros mailing list 05/01/2009
P1257470
(16+16) C+
BP in 12,5
Wieviele Lösungen?

2009 Lösungen!
2009 = (C(13,3)+1) * C(7,1)
comment
Keywords: Non-Unique Proof Game, Path enumeration (year), Capture-free
Genre: Retro, Mathematics
Computer test: Popeye
Input: A.Buchanan, 2012-12-26
Last update: A.Buchanan, 2017-8-30 more...
80 - P1257473
Noam D. Elkies
Retros mailing list 30/12/2007
P1257473
(16+0)
Serienzug-BP in 10
Wieviele Lösungen?

2008 Lösungen!
2008 = C(4,1) * C(2,1) * (C(10,5) - 1)
comment
Keywords: Path enumeration (year), Series mover, Non-Unique Proof Game
Genre: Retro, Mathematics, Fairies
Input: A.Buchanan, 2012-12-26
Last update: A.Buchanan, 2017-9-22 more...
81 - P1257475
Noam D. Elkies
Mark Watkins

Retros mailing list 03/01/2007
P1257475
(15+15)
BP in 6,5
Wieviele Lösungen?

2007 Lösungen!
2007 = (C(6,2)*C(3,1)) ^2 - C(4,2)*C(3,1)
comment
Keywords: Path enumeration (year), Non-Unique Proof Game
Genre: Retro, Mathematics
Input: A.Buchanan, 2012-12-26
Last update: A.Buchanan, 2012-12-27 more...
82 - P1258111
Noam D. Elkies
Retros mailing list 01/01/2013
P1258111
(16+16) C+
PG in 6,5
How many solutions?

2013 solutions!

(C(7,3)-1-1) * E_6
where Euler number, E_n, defined by generating function:
sec(x) + tan(x) = Sum(n=0...infinity) E_n (x^n/n!)
Here E_6 = 61.
Keywords: Path enumeration (year, Euler), Non-Unique Proof Game, Capture-free
Genre: Retro, Mathematics
Computer test: C+
Input: A.Buchanan, 2013-1-1
Last update: A.Buchanan, 2017-8-30 more...
83 - P1261476
Noam D. Elkies
H StrateGems 10/2001
P1261476
(2+15) C+
h#5.5. Castling Rights?
1. ... Kxe6 2. 0-0 Kxe7 3. Kh7 Ke6 4. Tg8 Kf7 5. Tg5 fxg5 6. Th8 g6#
play all play one stop play next play all
2. 0-0 is legal because otherwise could not have reached current diagram. All alternatives to 0. ... d6+ give immediate pat, as e6 is now guarded by pawn on d7.
Objective: Prove Black castling legal in an alive position (+ Type C last move).
Can the objective be achieved without check in diagram (i.e. Type B)?
comment
Keywords: Dead Position, Castling, Last Move?, Type C, Minimal
Genre: Retro
Computer test: C+ Popeye 4.5
Input: A.Buchanan, 2013-1-31
Last update: A.Buchanan, 2018-4-16 more...
84 - P1261570
Noam D. Elkies
S StrateGems 10/2001
P1261570
(16+1)
Last move?

BTM the game is stalemate, WTM the game is dead.
If Black moved last it was R: 0. Kh4-h3 g2-g3+ retropat. So it was White who moved last. All missing pieces were captured by wP, and none can be undone immediately, even wbP & wPh7. However there is a try R: 0. Bz-h5? Kh4-h3 1. g2-f3+ Kh5-h4 2. B-z+. But then 0. ... Kh4-h3 was mandatory into dead position, and although White has a move, he can't relieve the looming stalemate. So need to give Black a retro move which is not mandatory Kh4-h3 into dead position. The only solution is R: 0. ... 0-0 1. Kg2-h3, with many alternatives: basically anything but Kf1, Rg1 or Ne3, as Black must be allowed to respond Kg2.
Objective: Type A Last move with uncastling
comment
Keywords: Dead Position, Castling, Last Move?, Type A, Rex solus (S)
Genre: Retro
Reprints: 40 The Puzzling Side of Chess 145, p. 3, 07/04/2018
Input: A.Buchanan, 2013-2-2
Last update: A.Buchanan, 2018-4-7 more...
85 - P1285860
Noam D. Elkies
StrateGems (14) 04-06/2001
P1285860
(3+2) C+
ser-#10
Circe
1. d2-d4 2. b2-b4 3. b4-b5 4. b5-b6 5. d4-d5 6. d5-d6 7. d6-d7 8. d7-d8=D 9. b6xa7 10. a7-a8=D#
play all play one stop play next play all
Keywords: Series mover, Circe, Excelsior (2-fach DD)
Genre: Fairies
Computer test: %Popeye FreeBSD-4.0-RELEASE-32Bit-Version 3.65
Input: Erich Bartel, 2014-6-30
Last update: Alfred Pfeiffer, 2014-6-30 more...
86 - P1292681
Noam D. Elkies
Andrew Buchanan

C www.anselan.com , p. 50m.html, 18/01/2004
P1292681
(5+2) C+
Draw
Schwarz hat keinen letzten Zug, muss also ziehen
1. ... axb1=D+ 2. Kc3! Dxg6 (#63 laut Datenbank) 3. Lc5! with distance to zero = 103 single moves) Dg3+ 4. Kc4! Db8+ ist remis gemäß 50-Züge-Regel.
2. Kd2? Dxg6!
play all play one stop play next play all
Article 17 of the Codex for Chess Composition states: "Unless expressly stipulated, the 50 moves-rule does not apply to the solution of chess compositions except for retro-problems."
White with the move would immediately mate in 1, but the determination that Black is to move means that the problem is retro. So 1. ... axb1D+! 2. Kc3! Dxg6! 3. Bc5! is the slowest win for Black with 62 moves to mate, and there is no faster forced capture to allow Black to reset the clock. Article 17 therefore kicks in, and White secures the draw by 50M.
The position will be too simple to allow stalling for 50 moves after the capture, so this is the unique solution.
See http://www.anselan.com/50Msols.html for details.
more ...
comment
Keywords: 50 move rule, No legal last move for Black
Genre: Retro, Studies
Computer test: Nalimov tablebase for DTM. Multi-metric access for DTC (chess.jaet.org/endings/) 2018 re-analyzed with Stockfish 9+
Input: A.Buchanan, 2014-12-18
Last update: A.Buchanan, 2018-2-14 more...
87 - P1292682
Noam D. Elkies
D www.anselan.com , p. 50m.html, 18/01/2004
P1292682
(3+4) C+
Who wins?
Weiß hat keinen letzten Zug, muss also ziehen.
1. Txf1 (#87 laut Datenbank) ist remis gemäß 50-Züge-Regel
play all play one stop play next play all
Article 17 of the Codex for Chess Composition states: "Unless expressly stipulated, the 50 moves-rule does not apply to the solution of chess compositions except for retro-problems."
White has the move. (If not, Black would win with 1... Txg1#.) The determination who is to move means that the problem is retro. Now 1. Txf1! would win but for 50M, as 1... Nd4(h4+)! can delay capture for 71 moves.
So it's a draw.
See http://www.anselan.com/50Msols.html for details.
more ...
comment
Keywords: 50 move rule
Genre: Retro, Studies
Input: A.Buchanan, 2014-12-18
Last update: A.Buchanan, 2014-12-19 more...
88 - P1292870
Andrew Buchanan
Noam D. Elkies

Phénix 2004
P1292870
(13+13) C+
Proof game in 7.0
b) bPb7 to g7
c) bPc7 to g7
d) bPd7 to e7
a) 1. f4 a5 2. f5 a4 3. f6 a3 4. fxg7 axb2 5. gxf8=L bxa1=L 6. Lxe7 Lg7 7. Lf8 Lxf8
b) 1. f4 a5 2. f5 a4 3. f6 a3 4. fxe7 axb2 5. exd8=S bxa1=D 6. Sxb7 Df6 7. Sd8 Dxd8
c) 1. f4 a5 2. f5 a4 3. f6 a3 4. fxe7 axb2 5. exd8=L bxa1=D 6. Lxc7 Df6 7. Ld8 Dxd8
d) 1. f4 a5 2. f5 a4 3. f6 a3 4. fxg7 axb2 5. gxf8=S bxa1=L 6. Sxd7 Lg7 7. Sf8 Lxf8
play all play one stop play next play all
more ...
comment
Keywords: Unique Proof Game, Homebase (2), Ceriani-Frolkin Theme (L/S), Pronkin Theme (d/l), Prentos Theme (L/S), Switchback (L/S), Phoenix (d/l), Economy record
Genre: Retro
Input: A.Buchanan, 2014-12-22
Last update: A.Buchanan, 2018-2-16 more...
89 - P1293500
Noam D. Elkies
Retros mailing list 1/1/2014
P1293500
(16+0) C+
Serienzug-BP in 24
Wieviele Lösungen?
2014 Lösungen!

C(24,3) - C(5,2) = 2024-10 = 2014
comment
Keywords: Non-Unique Proof Game, Path enumeration (year), Series mover
Genre: Retro, Mathematics, Fairies
Input: A.Buchanan, 2014-12-29
Last update: A.Buchanan, 2017-9-22 more...
90 - P1299431
Noam D. Elkies
Retros mailing list 07/01/2015
P1299431
(16+16) C+
BP in 9.5
Wieviele Lösungen?
Beispiellösung:
1. a4 e6 2. a5 Dg5 3. Ta4 Dd5 4. Tf4 Lc5 5. b4 d6 6. Lb2 Kd7 7. Lf6 Kc6 8. e3 Sd7 9. Le2 g5 10. b5#
play all play one stop play next play all
2015 Lösungen
= 9!/(7!2!) * 8!/(5!3!) - 1
Autor: "... capture-free SPG enumeration where all the threads contribute to the final pure mate."
Henrik Juel: It should probably be BP 9.5, with these moves:
1.a4 e6 2.a5 Dg5 3.Ta4 Dd5 4.Tf4 Lc5 5.b4 d6 6.Lb2 Kd7 7.Lf6 Kc6 8.e3 Sd7 9.Le2 g5 10.b5+
The counting seems difficult.
Ignoring the last checking white move, the number of white sequences is 9!/(4!3!2!)=7200, so something is wrong (2015-3-21)
A.Buchanan: Yes it's definitely 9,5 moves - sorry for typo. However otherwise the diagram is correct, I believe. I have a different value from Henrik for number of White sequences. (2015-3-21)
Mario Richter: Perhaps Henrik overlooked that b2-b4 can follow only after wRa1 has reached f4?! (2015-3-21)
Henrik Juel: Yes, I did, Mario.
So the white moves are a4-a5.Ta4-f4.b4.Lb2-f6 and e3.Ld2, and finally b5+
The first black move is e6 and the remaining are Lc5.d6.Kd7-c6.Sd7 and Dg5-d5.g5
The single subtracted non-solution is
1.a4 e6 2.a5 Lc5 3.Ta4 d6 4.Tf4 Kd7 5.b4 Kc6 6.Lb2 Sd7 7.Lf6 Dg5? 8.e3 Dd5 9.Le2 g5 10.b5+
Once you are given the 'solution', the counting is not that difficult, after all (2015-3-21)
Henrik Juel: ... and moving Lf6 to (say) a1 gives an example for next year (2015-3-21)
comment
Keywords: Non-Unique Proof Game, Path enumeration (year), Capture-free
Genre: Retro, Mathematics
Computer test: C+ popeye
Input: A.Buchanan, 2015-3-17
Last update: A.Buchanan, 2017-8-30 more...
91 - P1304323
Noam D. Elkies
Shahmat 1986
Czerniak Memorial
3. Ehrende Erwähnung
P1304323
(4+3)
Gewinn
1. c5? Sxh6+ 2. Kf8 Sf5 3. cxb6 Sd6! remis
1. Kg7? Sxh6 2. Kxh6 Ke3 3. c5 bxc5 4. b6 c4 5. b7 c3 6. b8=D c2 7. Dh2 c1=D! remis
1. h7! Sf6+ Kg7 Sxh7 3. Kxh7 Ke3! 4. c5 bxc5 5. b6 c4 6. b7 c3 7. b8=D c2 8. Dh2! c1=D 9. Dh6+ gewinnt
8. ... Kd3 9. Df4,Dh6 Kc3 10. Dc1 gewinnt
3. ... Kd3 4. c5 bxc5 5. b6 c4 6. b7 c3 7. b8=D c2 8. Df4 gewinnt
play all play one stop play next play all

Genre: Studies
Input: Rainer Staudte, 2015-6-13
Last update: Rainer Staudte, 2015-6-13 more...
92 - P1308876
Noam D. Elkies
? 10/1991
P1308876
(4+4)
White to play and win (!?)
1. e6 a3 2. e7 Kb1! 3. e8=T!! a2 4. 0-0-0-0-0-0!! a1=D 5. Te1+ Kb2 6. Txa1 Dxa1 7. Kd4
play all play one stop play next play all
1.e6 a3 2.e7 Kb1!

After 2...Kb2 White's lead in the pawn race suffices: 3.e8Q
a2 4.Qe2+ Kb1 5.Kd1! But with the King already on b1, Black
safely Queens as well after 3.e8Q a2, and 4.Kd2 (the Queen endgame
with 4.Qe6 a1Q 5.Q:d5(b6) Kc2+ also gives White nothing) a1Q 5.Qe1+
Kb2 6.Q:a1+ K:a1 7.Kc3 Ka2 draws by a tempo. So White steals
a tempo with

3.e8R!! a2 4.0-0-0-0-0-0!!,

moving the King two squares toward the Rook, to e3, and the Rook
to e2 (a Black pawn controls the square e4 in the Rook's path,
but this in itself does not prohibit Castling...). Having rushed
his King to the third rank in one move, White now quickly wins:

4...a1Q 5.Re1+ Kb2 6.R:a1 Q:a1 7.Kd4

(4...d4+ 5.Ke4 is even easier). White also wins against 3...Kb2
with 4.0-0-0-0-0-0+!, and against other third moves White prevails
even without bending the rules (d4 4.Ke2 a2 5.Kf3 Kb2 6.Ra8 etc.).
Problem aficionados will note the "dual avoidance": 2...Kb2 3.e8R?
d4! and only Black can win.

(Author's solution)
Keywords: Joke, Castling (vertikal), Kindergarten Problem
Genre: Studies
Reprints: Shahmat 1995
Input: A.Buchanan, 2015-9-3
Last update: Alfred Pfeiffer, 2015-9-7 more...
93 - P1308962
Noam D. Elkies
Internet 1991
P1308962
(8+6)
White to move and draw
(50 moves rule allowed)
1. f6 Db3 2. f7!! Dd1+ 3. Kh6 Df3 4. Kg7 Dg4+ 5. Kh8 Df5 6. Kg7 Dg5+ 7. Kh7 Df6 8. Kg8 Dg6+ 9. Kf8! Ka4
10. Ke7 Dg7 11. Ke8 De5+ 12. Kd7 Df6 13. Ke8 De6+ 14. Kf8 Kb3
15. Kg7! De7 16. Kg8 Dg5+ 17. Kh8 Df6+ 18. Kg8 Dg6+ 19. Kf8 Kb2
20. Ke7 Dg7! 21. Ke8 De5+ 22. Kd8 Df6+ 23. Ke8 De6+ 24. Kf8 Kc1
25. Kg7 De7 26. Kg8 Dg5+ 27. Kh8 Dh6+ 28. Kg8 Dg6+ 29. Kf8 Kd1
30. Ke7 Dg7 31. Ke8 De5+ 32. Kd7 Df6 33. Ke8 De6+ 34. Kf8 Ke2
35. Kg7 De7 36. Kg8 Dg5+ 37. Kh8 Df6+ 38. Kg8 Dg6+ 39. Kf8 Kf3
40. Ke7 Dg7 41. Ke8 De5+ 42. Kd7 Df6 43. Ke8 De6+ 44. Kf8 Kf4
45. Kg7 De7 46. Kg8 Dg5+ 47. Kh7 Df6 48. Kg8 Dg6+ 49. Kf8 Ke5
50. Ke7 Dd6+ 51. Ke8 Ke6! and now the only move to complete the 100-ply count is 52. Sc2! 1/2-1/2

Other lines:

2. Kh6? Dd1! 3. f7 Df3 4. Kg7 Dg4+ 5. Kh8 Df5 6. Kg7 Dg5+ 7. Kh7 Df6 8. Kg8 Dg6+ 9. Kf8 Ka4 10. Ke7 Dg7 11. Ke8 De5+ 12. Kd7 Df6 13. Ke8 De6+ 14. Kf8 Kb3 15. Kg7 De7 16. Kg8 Dg5+ 17. Kh8 Df6+ 18. Kg8 Dg6+ 19. Kf8 Kb2 20. Ke7 Dg7 21. Ke8 De5+ 22. Kd8 Df6+ 23. Ke8 De6+ 24. Kf8 Kc1 25. Kg7 De7 26. Kg8 Dg5+ 27. Kh8 Df6+ 28. Kg8 Dg6+ 29. Kf8 Kd1 30. Ke7 Dg7 31. Ke8 De5+ 32. Kd7 Df6 33. Ke8 De6+ 34. Kf8 Ke2 35. Kg7 De7 36. Kg8 Dg5+ 37. Kh8 Df6+ 38. Kg8 Dg6+ 39. Kf8 Kf3 40. Ke7 Dg7 41. Ke8 De5+ 42. Kd7 Df6 43. Ke8 De6+ 44. Kf8 Kf4 45. Kg7 De7 46. Kg8 Dg5+ 47. Kh7 Df6 48. Kg8 Dg6+ 49. Kf8 Ke5 50. Ke7 Dg7 51. Ke8 Ke6 52. Kd8 Dxf7 0-1

9. Kh8? Dxf7! 10. Sc2 dxc2

15. Kg8? Kb2!

20. ... Dh7? 21. Kf6! delaying

No faster are:
50. ... Dg7 51. Ke8 Ke6 52. Kd8 1/2-1/2
50. ... De6+ 51. Kf8 Kf6 52. Kg8 1/2-1/2
play all play one stop play next play all
This is based around a known endgame KPKQ where wPf7 cannot be captured by bQ because it stalemates wKh8. However here White always has the losing move Sc2, so has not got the stalemate recourse.

White still must spend first 3 moves pushing Pf5 to f7 & K to h6. bQ can check on his 2nd move, so White can't just promote in 3 moves. White threatens at any point to promote, and which point Black no longer wins. Now bK is a long way from the action. Black strategy is to repeatedly chase wK to f8 in a 4 move sequence, at which point it is safe for bK to take a step closer. White must also avoid leaving Pf7 pinned, or letting bQ move to f8 safely.

There is a little flexibility in the moves, as the example solution shows. In particular, White on moves 5n+2 can move to the 7th or 8th row.

However the timing is very close. In order to claim the draw under 50 move rule, White must have moved 1. f6!, 2. f7! & 3. Kh6 to get the pawn moves over and done with. So the dual elimination happens 50 moves later!
Keywords: 50 move rule
Genre: Studies
Input: A.Buchanan, 2015-9-4
Last update: A.Buchanan, 2015-9-5 more...
94 - P1311896
Noam D. Elkies
Retros mailing list 14/09/2015
P1311896
(16+16) C+
KBP
Wieviele Lösungen?

5776 Lösungen!
(Jewish calendar New Year 14/09/2015)
comment
Keywords: Path enumeration (year), Non-Unique Proof Game, Symmetrical position, Capture-free
Genre: Retro, Mathematics
Input: A.Buchanan, 2015-11-11
Last update: A.Buchanan, 2017-8-30 more...
95 - P1311897
Noam D. Elkies
Retros mailing list 14/9/2015
P1311897
(16+16) C+
KBP
Wieviele Lösungen?

5775 Lösungen!
(Jewish calendar End of Old Year 13/09/2015)
more ...
comment
Keywords: Path enumeration (year), Non-Unique Proof Game, Capture-free
Genre: Retro, Mathematics
Input: A.Buchanan, 2015-11-11
Last update: A.Buchanan, 2018-1-28 more...
96 - P1325025
Noam D. Elkies
Retros mailing list 1/1/2016
P1325025
(16+16) C+
A) proof game in 8.5 moves; how many solutions?
B) sides reversed: proof game in 8.5; how many solutions?
Henrik Juel: White made 9 moves, 5 on the kings side, so 4 on the queens side
Kings side: 1 sequence Sf3-Sh5-f3-Kf2-Kg1
Queens side: 2 sequences c3-Dc2-Da4-b3 and c3-Db3-Da4-b3
Number of white sequences is 2xC(9,4)=252
Black made 8 moves, e6-Se7-Sec6-Ke7-Dd8-Sd8-c6 plus a5
Number of black sequences is 8
Number of solutions is 252x8=2016
part B analogously C(8,4)xC(9,2)=70x36=2520 solutions (2016-9-6)
comment
Keywords: Capture-free, Path enumeration (year), Non-Unique Proof Game
Genre: Retro, Mathematics
Input: A.Buchanan, 2016-9-6
Last update: A.Buchanan, 2016-12-7 more...
97 - P1338361
Richard Stanley
Noam D. Elkies

1 Problemas 18, p. 487, 04/2017
RPS version NDE
P1338361
(12+14)
How near can a game come to this position?
Keywords: Dead Position
Genre: Retro
Input: A.Buchanan, 2017-8-29
Last update: A.Buchanan, 2017-8-29 more...
98 - P1338400
Noam D. Elkies
Retros mailing list 1/1/2017
P1338400
(16+16)
KBP
Wieviele Lösungen?

2017 Lösungen
Henrik Juel: One solution is
1. Bb2-b3 Ba7-a5 2. Lc1-b2 Ta8-a6 3. Lb2-d4 Ta6-g6 4. Bc2-c3 Be7-e6 5. Dd1-c2 Dd8-e7 6. Dc2-d3 De7-a3 7. Dd3-f3 Bf7-f5 8. Bh2-h3 Ke8-f7 9. Th1-h2 Da3-c1# (2017-8-30)
A.Buchanan: There are 2 * (7+2)!/(7!2!) * (6+2)!/(6!2!) = 2016 easy solutions to spot, but then the 2017th is a lot sneakier. After a number of easy years, 2017 is a difficult number to force, and Noam let go of the Stanley aesthetic that all solutions should be rearrangements of the same moves. I was able to keep that in P1338411, but had to jettison the idea of symmetry. That aesthetic is actually a bit limiting, as it basically closes off the world of "additive" arithmetic which Noam exploits here, and forces one to remain with perhaps duller "subtractive" arithmetic. We shall see what 2018 brings. (2017-8-31)
Henrik Juel: The 2017th solution is as the one above, but
6.Df5 instead of 6.Dd3 (2017-8-31)
comment
Keywords: Non-Unique Proof Game, Path enumeration (year), Capture-free
Genre: Retro
Input: A.Buchanan, 2017-8-30
Last update: A.Buchanan, 2017-8-30 more...
99 - P1346158
Noam D. Elkies
Retros mailing list 1/1/2018
P1346158
(14+16) C+
KBP
Wieviele Lösungen?
(Beispiellösung)
1. e4 e6 2. Lb5 Ke7 3. Se2 d5 4. Tg1 dxe4 5. d3 exd3 6. Sd2 Dd6 7. Sb3 Da6 8. Ld2 Ld7 9. Tc1 Lc6 10. Sa1 Sd7 11. b3 Tb8
play all play one stop play next play all
2018 Lösungen
Henrik Juel: The shortest proof game lasts 11.0 moves, e.g.,
1.e4 e6 2.Lb5 Ke7 3.Se2 d5 4.Tg1 dxe4 5.d3 exd3 6.Sd2 Dd6 7.Sb3 Da6 8.Ld2 Ld7 9.Tc1 Lc6 10.Sa1 Sd7 11.b3 Tb8
The first two white moves are fixed, and there are (9 over 2)=36 ways to place Se2-Tg1 in the subsequent white play
The first three black moves are fixed (to avoid the check 2.Lb5+), and there are (8 over 2)=28 ways to place dxe4xd3 in the subsequent black play; the remaining black moves admit 2 sequences: Dd6-Da6-Ld7 and Dd6-Ld7-Da6 etc.
So there are 36x28x2=2016 solutions with these moves
Additionally there are 2 solutions with 5.d4 exd3ep (and 7... Da6/Ld7)
The en passant trick must be a first in this new year greeting genre (2018-1-26)
A.Buchanan: It's interesting that this problem, although dated recently, has not been blocked to those who are not logged in, by the automatic blocker-of-recent=problems. That suggests that the blocker must have some sensitivity to the source, and e.g. will not block originals from RML or I suggest PDB itself. (2018-1-28)
comment
Keywords: Non-Unique Proof Game, Path enumeration (year), En passant
Genre: Retro, Mathematics
Computer test: C+ Popeye 3.41 in about 2 seconds
Input: A.Buchanan, 2018-1-26
Last update: A.Buchanan, 2018-1-28 more...
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