

(1) Posted by Hauke Reddmann [Thursday, Sep 16, 2021 12:23] 
Longest automatic play with decision Some asked on CSE  I could swear we had this here, but can also imagine the record
has been upped meanwhile. The longest variant forced for both sides is well known
(at least I would know where to search for it :). How long is the
longest variant forced for both sides, with the last move ending the game? 

(2) Posted by Rewan Demontay (Real Name: James Malcom) [Thursday, Sep 16, 2021 14:29] 
For checkmate, Khanyan still reigns supreme.
Alexey Khanyan, Tim Krabbe's Website Diary Entry #267 2008, #11 (= 13+13 )
1... Ng2f4+ 2. Rfxf4+ N2xf4+ 3. Rgxf4+ Nh3xf4+ 4. Rhxf4+ Ndxf4+ 5. Rxf4+ Nhxf4+ 6. Rxf4+ Ngxf4+ 7. Rxf4+ Nxf4+ 8. Rxf4+ Kxf4+ 9. Qee5+ Qxe5+ 10. Qaxe5+ Rgxe5+ 11. Qxe5+ Rxe5+ 12. Qxe5#
For stalemate, dead position would have to be ignored. I have no idea what the record here is. 

(3) Posted by Joost de Heer [Thursday, Sep 16, 2021 15:34] 
>For stalemate, dead position would have to be ignored. I have no idea what the record here is.
If all moves are forced, the position is already dead, so only dead positions would satisfy the original question. And stalemate isn't the only reason for automatic draw of course, insufficient mating material works also. 

(4) Posted by Andrew Buchanan [Friday, Sep 17, 2021 08:35] 
Dead position rule would not apply unless the problem is retro, under Codex Article 17A, which I support. No clumsy “ignore” is necessary. 

(5) Posted by Hauke Reddmann [Friday, Sep 17, 2021 11:34] 
(= 9+7 )
OK, then lets start constructing :) 12 halfmoves after Bb7+, improve 
can you fill the 7th row and permute Qs such that Rb1 must make the last capture? 

(6) Posted by Frank Richter [Friday, Sep 17, 2021 19:59] 
Autoplay with Ka6a5? 

(7) Posted by Hauke Reddmann [Saturday, Sep 18, 2021 10:30] 
Somehow a block on a5 got away :) 

(8) Posted by Hauke Reddmann [Saturday, Sep 18, 2021 14:45] 
Obvious "after Khanyan" is obvious (16 plies):
(= 14+10 )


(9) Posted by Joost de Heer [Saturday, Sep 18, 2021 15:43] 
In fairy chess, the longest I know of is a s#50 by Unto Heinonen
(= 15+16 )
s#50 Double maximum
1.Fd3! Td1 2.Ff1 Tb3 3.Fd3 Th1 4.Ff1 T×f3 5.Fd3 Td1 6.Ff1 Tb3 7.Tf2 F×é6 8.Tf5 Tf3 9.Fd3 Th1 10.Ff1 Tb3 11.Tf2 Fh3 12.Tf5 Tf3 13.Fd3 Td1 14.Ff1 Tb3 15.Tf2 F×d7 16.Tf5 Tf3 17.Fd3 Th1 18.Ff1 Tb3 19.Tf2 Fh3 20.Tf5 Tf3 21.Fd3 Td1 22.Ff1 Tb3 23.Tf2 Fç8 24.Tf5 F×f5 25.Fd3 Fç8 26.Fg6 Fh3 27.F×ç2 Fç8 28.Fg6 Fh3 29.Fb1+ R×b1 30.Tb7 Fç8 31.T×b4 Fh3 32.Tb7 Fç8 33.T×b3 Fh3 34.T×g3 Fç8 35.T×a3 Fh3 36.T×h3 Da7 37.Ta3 F×é5 38.Th3 Da1 39.Ta3 Fh2 40.Th3 Da7 41.Ta3 F×d6 42.Th3 Da1 43.Ta3 Fh2 44.Th3 F×ç7 45.Ta3 Fh2 46.F×h2 Th1 47.Fb8 T×h6 48.Fh2 T×h2 49.Th3 Da7 50.Ta3 D×h7‡ 

(10) Posted by Rewan Demontay (Real Name: James Malcom) [Saturday, Sep 18, 2021 17:25] 
Andrew, I disagree. I believe dead positioning is being invoked since we are speaking of automatic ending by the rules.
Joost, I direct you towards this: https://pdb.dieschwalbe.de/P0000847 

(11) Posted by Joost de Heer [Saturday, Sep 18, 2021 19:26] 
@James: Last move isn't forced, so it doesn't satisfy the criteria for this thread. 

(12) Posted by Rewan Demontay (Real Name: James Malcom) [Sunday, Sep 19, 2021 01:18] 
Have a #55 then: https://pdb.dieschwalbe.de/P0000832
Hans Heinrich Schmitz, Die Schwalbe, 10/1969, Double Maximummer #55
(= 15+15 )
1... Kxa7 2. Ra2+ Ra3 3. Rh2 Rxe3 4. Ra2+ Ra3 5. Rh2 Rxf3 6. Ra2+ Ra3 7. Rh2
Rxg3 8. Ra2+ Ra3 9. Rh2 Rh3 10. Qh6 Ra3 11. Ra2 Bf4 12. Rh2 Rh3 13. Qxe6 Ra3 14.
Ra2 Bc1 15. Rh2 Rh3 16. Qh6 Ra3 17. Ra2 Bf4 18. Rh2 Rh3 19. Qxd6 Ra3 20. Ra2 Bc1
21. Rh2 Rh3 22. Qh6 Ra3 23. Ra2 Bf4 24. Rh2 Rh3 25. Qxc6 Ra3 26. Ra2 Bc1 27. Rh2
Rh3 28. Qh6 Ra3 29. Ra2 Bf4 30. Rh2 Rh3 31. Qxb6+ Nxb6 32. Rxf7 Ra3 33. Ra2 Bc1
34. Rh2 Rh3 35. Rh7 Ra3 36. Ra2 Bf4 37. Rh2 Rh3 38. Rxe7 Ra3 39. Ra2 Bc1 40. Rh2
Rh3 41. Rh7 Ra3 42. Ra2 Bf4 43. Rh2 Rh3 44. Rxd7 Ra3 45. Ra2 Bc1 46. Rh2 Rh3 47.
Rh7 Ra3 48. Ra2 Bf4 49. Rh2 Rh3 50. Rxc7 Ra3 51. Ra2 Bc1 52. Rh2 Rh3 53. Rh7 Ra3
54. Ra2 Bf4 55. Rh2 Rh3 56. Rxb7# 

(13) Posted by Hauke Reddmann [Sunday, Sep 19, 2021 11:17] 
Ha! That one I saw just two weeks ago at the Lüneburg meeting.
(Obviously, doublemax is a bit of cheating, strongly limiting
the possible moves...) 

(14) Posted by Rewan Demontay (Real Name: James Malcom) [Sunday, Sep 19, 2021 14:52] 
Here is 21 ply for stalemate.
(= 4+11 )


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