when the spring comes (NEW 2v16 LENGTH RECORD ?!)

[Paloma]

No problem for SlowChess having had a little Forward- Backward:

What about this one?
7k/4p3/4p3/8/8/5pp1/P2Kprrb/4nbqn w - - 0 1
Is it winning for White? If yes, can you get the exact DTM?

[fen]7k/4p3/4p3/8/8/5pp1/P2Kprrb/4nbqn w - - 0 1[/fen]

[peter]

No problem for SlowChess having had a little Forward- Backward:

What about this one?
7k/4p3/4p3/8/8/5pp1/P2Kprrb/4nbqn w - - 0 1
Is it winning for White? If yes, can you get the exact DTM?

First question: yes.
Second one: 40 moves.

Pity both only, if Black moves 6...e4 after

1. Kxe1 Kg7 2. a4 Kf6 3. a5 Kf5 4. a6 e5
5. a7 e6 6. a8=Q
6...e4(?):

[fen]Q7/8/4p3/5k2/4p3/5pp1/4prrb/4Kbqn w - -[/fen]


66/68 0:55 +M34 7.Da5+ Kg6 8.De5 Kf7 9.Dg5 Kf8
10.Df6+ Ke8 11.Dg7 Kd8 12.Db7 e3
13.Df7 Kc8 14.Da7 e5 15.Db6 Kd7
16.Dc5 Kd8 17.Dc6 Ke7 18.Dc7+ Ke8
19.Dh7 Kd8 20.Db7 (5.960.977.200) 106554

[Hobacle]

7k/4p3/4p3/8/8/5pp1/P2Kprrb/4nbqn w - - 0 1
Is it winning for White? If yes, can you get the exact DTM?

First question: yes.
Second one: 40 moves.

Pity both only, if Black moves 6...e4 after

1. Kxe1 Kg7 2. a4 Kf6 3. a5 Kf5 4. a6 e5
5. a7 e6 6. a8=Q
6...e4(?):

[fen]Q7/8/4p3/5k2/4p3/5pp1/4prrb/4Kbqn w - -[/fen]


66/68 0:55 +M34 7.Da5+ Kg6 8.De5 Kf7 9.Dg5 Kf8
10.Df6+ Ke8 11.Dg7 Kd8 12.Db7 e3
13.Df7 Kc8 14.Da7 e5 15.Db6 Kd7
16.Dc5 Kd8 17.Dc6 Ke7 18.Dc7+ Ke8
19.Dh7 Kd8 20.Db7 (5.960.977.200) 106554

But White is able to win only after two black pawns move to e3 and e4, and he cannot capture any Black pieces, so Black shouldn't move his pawns actively, so this is probably not enough to prove the win.
Now, after 1.Kxe1 e5 SF11 gets a score of +147.92, but 1...Kg7 probably draws. I'm considering moving the e6 pawn to e5 in the beginning position. Then White is surely winning, we can spend all of the time in finding the exact DTM.

[Hobacle]

[fen]8/4p2p/7p/4pp1k/8/5pp1/P2Kprrb/4nbqn w - - 0 1[/fen]


Analysis by Stockfish 11 64:

1.Kxe1 Kg6 2.a4 h5 3.a5 h4 4.a6 h5 5.a7 h3 6.a8Q Kg5 7.Qg8+ Kh6 8.Qf8+ Kg6 9.Qd8 Kh6 10.Qg8 e4 11.Qf7 e3 12.Qxf5 h4 13.Qxh3 Kg5 14.Qe6 h3 15.Qxh3 Kf6 16.Qh5 Ke6 17.Qc5 Kf6 18.Qd5 Kg6 19.Qe6+ Kg5 20.Qe4 Kf6 21.Qa4 Kf5 22.Qc2+ Kg5 23.Qh7 Kf4 24.Qh6+ Ke5 25.Qh4 Kd5 26.Qh3 Kc5 27.Qf5+ Kb4 28.Qc2 e6 29.Qb2+ Ka5 30.Qh8 Ka6 31.Qa8+ Kb5 32.Qa1 Kb4 33.Qd4+ Kb3 34.Qb6+ Ka2 35.Qa5+ Kb1 36.Qb4+ Kc2 37.Qe4+ Kb2 38.Qf4 Ka3 39.Qg5 Kb3 40.Qb5+ Ka2 41.Qc4+ Ka3 42.Qc1+ Ka2
+- (147.92) Depth: 68/83 00:01:38 115MN

[peter]

[fen]8/4p2p/7p/4pp1k/8/5pp1/P2Kprrb/4nbqn w - - 0 1[/fen]


Analysis by Stockfish 11 64:

1.Kxe1 Kg6 2.a4 h5 3.a5 h4 4.a6 h5 5.a7 h3 6.a8Q Kg5 7.Qg8+ Kh6 8.Qf8+ Kg6 9.Qd8 Kh6 10.Qg8 e4 11.Qf7 e3 12.Qxf5 h4 13.Qxh3 Kg5 14.Qe6 h3 15.Qxh3 Kf6 16.Qh5 Ke6 17.Qc5 Kf6 18.Qd5 Kg6 19.Qe6+ Kg5 20.Qe4 Kf6 21.Qa4 Kf5 22.Qc2+ Kg5 23.Qh7 Kf4 24.Qh6+ Ke5 25.Qh4 Kd5 26.Qh3 Kc5 27.Qf5+ Kb4 28.Qc2 e6 29.Qb2+ Ka5 30.Qh8 Ka6 31.Qa8+ Kb5 32.Qa1 Kb4 33.Qd4+ Kb3 34.Qb6+ Ka2 35.Qa5+ Kb1 36.Qb4+ Kc2 37.Qe4+ Kb2 38.Qf4 Ka3 39.Qg5 Kb3 40.Qb5+ Ka2 41.Qc4+ Ka3 42.Qc1+ Ka2
+- (147.92) Depth: 68/83 00:01:38 115MN

This one's probably too trivial for you, isn't it?


[fen]7k/8/4p3/8/4p3/5pp1/P2Kprrb/4nbqn w - - 0 1[/fen]


Analysis by MateFinder 050320 64:

1.Kxe1 Kg7 2.a4 Kf6 3.a5 Ke7 4.a6 Kd6 5.a7 Kc5 6.a8Q Kb4 7.Qc6 Kb3 8.Qc1 Kb4 9.Qc2 Ka3 10.Qb1 e3 11.Qc2 Kb4 12.Qd3 Kc5 13.Qb3 Kd4 14.Qc2 Kd5 15.Qc7 Kd4 16.Qc6 Kd3 17.Qc5 Ke4 18.Qd6 Kf5 19.Qd4 Kg5 20.Qe5+ Kg6 21.Qf4 Kg7 22.Qg5+ Kf8 23.Qd8+ Kf7 24.Qh8 Ke7 25.Qd4 e5 26.Qd3 Ke8 27.Qh7 Kd8 28.Qb7 e4 29.Qc6 Ke7 30.Qd5 Kf6 31.Qd6+ Kf7 32.Qd7+ Kf6 33.Qe8 Kg7 34.Qe7+ Kg6 35.Qf8 Kh7 36.Qf7+ Kh8 37.Qe7 Kg8 38.Qf6 Kh7 39.Qf8 Kg6 40.Qe7 Kf5 41.Qd6 Kg5 42.Qe6 Kf4 43.Qd5 Kg4 44.Qe5 Kh4 45.Qe7+ Kg4 46.Qf6 Kh5 47.Qg7 Kh4 48.Qg6
+- (#49) Depth: 87/95 00:00:01 86001kN

[Hobacle]

[fen]8/4p2p/7p/4pp1k/8/5pp1/P2Kprrb/4nbqn w - - 0 1[/fen]


Analysis by Stockfish 11 64:

1.Kxe1 Kg6 2.a4 h5 3.a5 h4 4.a6 h5 5.a7 h3 6.a8Q Kg5 7.Qg8+ Kh6 8.Qf8+ Kg6 9.Qd8 Kh6 10.Qg8 e4 11.Qf7 e3 12.Qxf5 h4 13.Qxh3 Kg5 14.Qe6 h3 15.Qxh3 Kf6 16.Qh5 Ke6 17.Qc5 Kf6 18.Qd5 Kg6 19.Qe6+ Kg5 20.Qe4 Kf6 21.Qa4 Kf5 22.Qc2+ Kg5 23.Qh7 Kf4 24.Qh6+ Ke5 25.Qh4 Kd5 26.Qh3 Kc5 27.Qf5+ Kb4 28.Qc2 e6 29.Qb2+ Ka5 30.Qh8 Ka6 31.Qa8+ Kb5 32.Qa1 Kb4 33.Qd4+ Kb3 34.Qb6+ Ka2 35.Qa5+ Kb1 36.Qb4+ Kc2 37.Qe4+ Kb2 38.Qf4 Ka3 39.Qg5 Kb3 40.Qb5+ Ka2 41.Qc4+ Ka3 42.Qc1+ Ka2
+- (147.92) Depth: 68/83 00:01:38 115MN

This one's probably too trivial for you, isn't it?

But we ought to get its exact DTM, because it may be an earthshaking record of KPv16.

[peter]

But we ought to get its exact DTM, because it may be an earthshaking record of KPv16.

Too long for an exact DTM by Backward with game playing engine. Maybe somebody can find clever Chest- params, in Autoturbo- Mode no good chances neither, as far as I saw till now.
BTW, I don't think it to be so much longer then the one with the necessary pawns only. About something like this maybe?
[pgn][Event "?"]
[Site "?"]
[Date "2021.10.01"]
[Round "?"]
[White "Hobacle, Spring"]
[Black "2, 16"]
[Result "*"]
[SetUp "1"]
[FEN "8/4p2p/7p/4pp1k/8/5pp1/P2Kprrb/4nbqn w - - 0 1"]
[PlyCount "103"]

1. Kxe1 Kg6 2. a4 h5 3. a5 h4 4. a6 h5 5. a7 h3 6. a8=Q Kg5 7. Qg8+ Kh6 8. Qf8+
Kg6 9. Qd8 Kh6 10. Qg8 e4 11. Qf7 e3 12. Qxf5 h4 13. Qxh3 Kg5 14. Qe6 h3 15.
Qxh3 Kf6 16. Qh5 Ke6 17. Qc5 Kf6 18. Qd5 Kg6 19. Qe6+ Kg5 20. Qe4 Kf6 21. Qd5
Kg6 22. Qe5 Kf7 23. Qf5+ Kg8 24. Qd5+ Kf8 25. Qc4 Ke8 26. Qe6 Kd8 27. Qc6 e6
28. Qb7 e5 29. Qc6 Ke7 30. Qc7+ Ke8 31. Qg7 Kd8 32. Qb7 e4 33. Qf7 Kc8 34. Qa7
Kd8 35. Qb7 Ke8 36. Qc7 Kf8 37. Qd7 Kg8 38. Qe7 Kh8 39. Qg5 Kh7 40. Qe5 Kg8 41.
Qf6 Kh7 42. Qf8 Kg6 43. Qe7 Kf5 44. Qd6 Kg5 45. Qe6 Kh5 46. Qf6 Kg4 47. Qf8 Kg5
48. Qf7 Kg4 49. Qf6 Kh3 50. Qg7 Kh4 51. Qg6 Kh3 52. Qh5# *[/pgn]

[Hobacle]

But we ought to get its exact DTM, because it may be an earthshaking record of KPv16.

BTW, I don't think it to be so much longer then the one with the necessary pawns only.

So here is a solution.
Try this: 8/4p3/8/4p2k/8/5pp1/P2Kprrb/4nbqn w - - 0 1
Then we can add other pawns gradually.

But we're setting a record of KPv16, so other pawns are not unnecessary.

[peter]

But we ought to get its exact DTM, because it may be an earthshaking record of KPv16.

Too long for an exact DTM by Backward with game playing engine.

Best so far ist SF MOJO with unchecked Null Move pruning.
Even maybe 20 moves shorter then I had thought before with 10...e4 (? as in latest .pgn):

[pgn][Event "?"]
[Site "?"]
[Date "2021.10.01"]
[Round "?"]
[White "Hobacle, Spring"]
[Black "16, 2"]
[Result "*"]
[SetUp "1"]
[FEN "8/4p2p/7p/4pp1k/8/5pp1/P2Kprrb/4nbqn w - - 0 1"]
[PlyCount "61"]

1. Kxe1 Kg6 2. a4 h5 3. a5 h4 4. a6 h5 5. a7 h3 6. a8=Q Kg5 7. Qg8+ Kh6 8. Qf8+
Kg6 9. Qd8 Kh6 10. Qg8 e4 11. Qf7 e3 12. Qg8 h4 13. Qf7 Kg5 14. Qg7+ Kh5 15.
Qh7+ Kg5 16. Qf7 f4 17. Qe6 Kh5 18. Qg8 Kh6 19. Qg4 Kh7 20. Qg5 e6 21. Qg4 e5
22. Qg5 Kh8 23. Qg6 e4 24. Qh6+ Kg8 25. Qf6 Kh7 26. Qf8 Kg6 27. Qe7 Kf5 28. Qd6
Kg5 29. Qe6 Kh5 30. Qf6 Kg4 31. Qg6# *
[/pgn]

Yet 10...e6 could make it longer again, it's getting too time- consuming for me now regards

[Spliffjiffer]

for those who want to experiment...Chest could be a good help here...just an example so far, more to come hopefully later...i take the initial position for which Paloma gave the Diagram:
[d]7k/4p3/4p3/8/8/5pp1/P2Kprrb/4nbqn w - - 0 1
after 1.Kxe1 !! e5 ?, Chest gives a mate within around 4 sec with these parameters (pretty sure that PieceLimit and MaxMoves are perfectly chosen):
ChestUci-parameters:
<
HashSize: 2048 mb
ProblemType: mate
SearchDepth: 128
SearchMode: special
ChecksOnly: 14
KingSquares: 9 (or 0, that makes no difference)
PieceLimit: 3
MaxMoves: 11

everything else on default
>
have a try on your own and u will see