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I am not sure how to insert a position, so hopefully someone can help me out. I have just played a 3 minute game, we had the following position (I was Black)

White a2 b3 g3 h3 Kg2 Rf2 Nb6 Qa7
Black b4 d6 e7 f7 g6 h5 Kg7 Rc8 Qd5 Nf3

The game finished Nh4+ Kh2 Nf3 Kg2 Nh4+ Kh2 Nf3+ Kg2 and a draw by repetition. What did my opponent say immediately after the game?

Is there a finish Nh4+ Kh2 followed by Qg2+ Rxg2 Nf3+ Kh1 Rc1+ Rg1 Rxg1++ ?

Matthew Turner wrote: ↑

Mon Apr 05, 2021 10:26 pm

I am not sure how to insert a position, so hopefully someone can help me out. I have just played a 3 minute game, we had the following position (I was Black)

White a2 b3 g3 h3 Kg2 Rf2 Nb6 Qa7
Black b4 d6 e7 f7 g6 h5 Kg7 Rc8 Qd5 Nf3

The game finished Nh4+ Kh2 Nf3 Kg2 Nh4+ Kh2 Nf3+ Kg2 and a draw by repetition. What did my opponent say immediately after the game?

I suspect he suggested an improvement on Nf3+

Joseph,
We know why you are 2450 now!!

2r5/Q3ppk1/1N1p2p1/3q3p/1p6/1P3nPP/P4RK1/8 b - - 0 1

The above was generated by this: (Click the "pos" option in the full editor and then insert FEN between the start and end tags.)

An interesting variation on the standard smothered mate concept.

On the subject of interesting finishes from lichess games, here's an ending I had recently (I was white):
The engine says draw. I don't think I've ever had a similar ending before, either online or in person.

Interesting that bringing the BK closer to White's (after forcing it to b8) doesn't win, presumably White can use their B to stop that working?

Matt Mackenzie wrote: ↑

Tue Apr 06, 2021 3:05 pm

Interesting that bringing the BK closer to White's (after forcing it to b8) doesn't win, presumably White can use their B to stop that working?

My impression is that Black has to be careful not to lose, as in some lines the bishop might be able to block the perpetual checks, but then the Black queen can simply pin the white b-pawn to prevent its promotion. I don't think White can ever prevent this, but equally Black won't ever have enough time to bring the king closer, and even then there are some lines where pushing the g-pawn at the right moment will win for White. I wonder if the assessment is different if you:

(a) remove the g-pawn from the board (e.g. stick the White bishop on d4 instead);
(b) construct a similar position where the queening square is the opposite colour to that of the bishop (e.g. white pawn on c7, or more realistically, flip it slightly so the White pawn is on g7)?

Original position:

2K5/1P6/2q2Bk1/6P1/8/2P5/8/8

Variant 1:

2K5/1P6/2q3k1/8/3B4/2P5/8/8

Variant 2:

5K2/6P1/5q2/1kB5/1P6/8/5P2/8

I think they are all still drawn. Not checked with an engine.

Are these sort of positions in the 7-man tablebases?

If there are any study-like positions with this balance of material, that might be one approach to finding them.

Christopher Kreuzer wrote: ↑

Tue Apr 06, 2021 11:08 pm

Matt Mackenzie wrote: ↑

Tue Apr 06, 2021 3:05 pm

Interesting that bringing the BK closer to White's (after forcing it to b8) doesn't win, presumably White can use their B to stop that working?

My impression is that Black has to be careful not to lose, as in some lines the bishop might be able to block the perpetual checks, but then the Black queen can simply pin the white b-pawn to prevent its promotion. I don't think White can ever prevent this, but equally Black won't ever have enough time to bring the king closer, and even then there are some lines where pushing the g-pawn at the right moment will win for White. I wonder if the assessment is different if you:

(a) remove the g-pawn from the board (e.g. stick the White bishop on d4 instead);
(b) construct a similar position where the queening square is the opposite colour to that of the bishop (e.g. white pawn on c7, or more realistically, flip it slightly so the White pawn is on g7)?

Original position:

2K5/1P6/2q2Bk1/6P1/8/2P5/8/8

Variant 1:

2K5/1P6/2q3k1/8/3B4/2P5/8/8

Variant 2:

5K2/6P1/5q2/1kB5/1P6/8/5P2/8

I think they are all still drawn. Not checked with an engine.

Are these sort of positions in the 7-man tablebases?

If there are any study-like positions with this balance of material, that might be one approach to finding them.

I did something similar to this. You can check all these positions out with the endgame database at shredderchess. I came to the conclusion that it was a bit of a freak position and everything needed to be where it was to secure a draw.

Christopher Kreuzer wrote: ↑

Tue Apr 06, 2021 11:08 pm

I think they are all still drawn. Not checked with an engine.

Are these sort of positions in the 7-man tablebases?

There's an Android app which looks up Lomonosov tables.

Verdicts
Variant 1:
2K5/1P6/2q3k1/8/3B4/2P5/8/8
Drawn (as is the original position)


Variant 2:
5K2/6P1/5q2/1kB5/1P6/8/5P2/8
Mate in 24

Roger de Coverly wrote: ↑

Wed Apr 07, 2021 1:21 am

Christopher Kreuzer wrote: ↑

Tue Apr 06, 2021 11:08 pm

I think they are all still drawn. Not checked with an engine.

Are these sort of positions in the 7-man tablebases?

There's an Android app which looks up Lomonosov tables.

Verdicts
Variant 1:
2K5/1P6/2q3k1/8/3B4/2P5/8/8
Drawn (as is the original position)

Focusing on this 6-man position, as am using the the verdicts at shredderchess (I think the online one only does 6-man positions):

https://www.shredderchess.com/online/en ... abase.html

If you move the Black king around the board, the positions are either drawn or won depending on the distance of the king from the action on b7. Some interesting points arise. Maybe someone can do this for the 7-man positions (i.e. move the Black king around)?

Draw if the Black king is anywhere valid on the g-file or h-file.
Draw if the Black king is on f8 [this is rather surprising] (or f1, f3, f4).
Win if the Black king is on f7, f5.
Win e4, e6, e7, e8. Drawn elsewhere on e-file. e4 seems 'further away' than f8, but is won.
Win d5 and d6, unsurprisingly. Surprisingly, also won for Black king on d3.

Drawn anywhere valid on 1st and second ranks.

Win on a3 and b3 (surprisingly), and (less surprisingly) on c4 and a4, and (obviously) on a5 and b5 and a6.

So can anyone explain why the following two positions are drawn and won for Black respectively? (And what the main defensive manoeuvres are for White?)

Drawn:

2K2k2/1P6/2q5/8/3B4/2P5/8/8 w - - 0 1

Win for Black:

2K5/1P6/2q5/8/3B4/2Pk4/8/8 w - - 0 1

Christopher Kreuzer wrote: ↑

Wed Apr 07, 2021 10:05 am

Win for Black:
2K5/1P6/2q5/8/3B4/2Pk4/8/8 w - - 0 1

There's an obvious winning plan of K-c4-b5-a6(or c6) and then Qxb7 mate.

That works if the Black King just shuffles between b8 and a8. If however it tries to escape with .. Ka7 and .. Kb6, White has Qb5 putting the King back in the zugswang box and enabling the White King to advance.

In normal circumstances King and b pawn loses to King and Queen. The extra material seemingly can make a difference by controlling a7,b6 and c5.

Christopher Kreuzer wrote: ↑

Wed Apr 07, 2021 10:05 am

Focusing on this 6-man position, as am using the the verdicts at shredderchess (I think the online one only does 6-man positions):

The full 7-man tablebase is available on Lichess even without an account. In order to use it click on tools and then board editor where you can set up a position. Then click on analysis board and click the book icon next to the bottom right of the board.

Syzygy 7 man endgame tablebase too