29 May 2022

Schlage -- Ahues 1921: Historical Inquiry

A substantial number of chess endgame books present a position said to have been from a drawn game between Willi Schlage (1888-1940) with White and Carl Oscar Ahues (1883-1968). The game was played in Berlin in 1921, but no event is listed. Nor has a complete game score appeared. Schlage missed a win, as later pointed out by Ilya Maizelis.

White to move
From this position, Schlage started well, but his second move demonstrated that he did not discover the critical idea.

1.Ke6 Kc3 2.Kd6 

Maizelis pointed out that 2.Kd5! would have won.

2...Kd4 3.Kc6 Ke5 4.Kb7 Kd6 5.Kxa7 Kc7 1/2-1/2

As this ending appears in Mark Dvoretsky, Dvoretsky's Endgame Manual (2003), the position is on one of my pawn ending flash cards. Many of my students have tried to find the solution and then had it shown to them. When I encountered it this morning in Paul Keres, Practical Chess Endings (1974), I wanted to know more about the game. Searching for a game score took me down a rabbit hole of book after book. If no game can be found, then perhaps I can trace the analysis back to first publication.

It certainly did not originate with Jesus de la Villa, 100 Endgames You Must Know Workbook (2019) that a Wikipedia editor referenced. To the credit of the Wikipedia editors, Keres is also credited with presenting this ending.

Keres does not credit Maizelis, but Dvoretsky does. Chess Informant's Encyclopedia of Chess Endings: Pawn Endings (1982) has the position as number 65 and credits Maizelis with the solution.

My next step is the inquiry was Pawn Endings (1974) by Yuri Averbakh and Ilya Maizelis. An editor added to the text: "Maizelis was the first to point out the correct solution. so position No. 78 must be credited to him. Rabinovich indicated this in the first edition of his book, Chess Endgames, 1927" (26).

Happily, Mongoose Press brought out an English edition of the second edition (1938) of Rabinovich's text: Ilya Rabinovich, The Russian Endgame Handbook, trans James Marfia (2012). Rabinovich credits "I.M.", which he calls a pseudonym, with mentioning in the Soviet magazine 64 (1925, No. 6) that White's king "should move according to the most twisted, broken route" (as quoted by Rabinovich). Perhaps someone has access to old copies of 64 and can read Russian. I still have questions.

25 May 2022

One Queen Too Many

Four moves after my opponent promoted a second pawn, my rook and queen delivered checkmate while White's two queens idly watched.

How did this come about? Where did White go wrong?

We take up the game after White's 37.Kg5.

Black to move

Black's position seems hopeless.

37...Nxe6+ 38.Bxe6 Kxe6 39.Kh6 e3

White to move


White needs to push another pawn. 40.g4+-

40...d4= 41.g4 Ke5??

The king is needed elsewhere.

41...Kf7= 42.Rf1+ (42.g5?? Rd6+ 43.Kh5 Kg7-+) 42...Ke6 43.Re1=


White is back in control.

42...Ke4 43.g6 d3 44.g7 Rd6+ 45.Kg5 d2

White to move


White spent 31 seconds--half of their remaining time in this 3 2 blitz game on this blunder.


The rook can always remove the first queen and White's pawns are promoting first.

46...Kxe3= 47.h8Q d1Q

White to move


Stockfish offers a long line that essentially leads to a draw by repetition.

48.Qh3+ Kd2 49.Qg2+ Kd3 50.g8Q

Black to move
Analysis Diagram

50...Qc1+ 51.Kg4 Rd4+ 52.Kh5 Qd1+ 53.Kg5 Qc1+


Now Black is winning.

49.g8Q Qg1+ 50.Kf5 Qf2+

White to move

White steps into checkmate.

After 51.Kg5 Black has a lot of work to do to convert a one pawn advantage in a queen ending after first forcing White to exchange the second queen for Black's rook. 51...Qg3+ 52.Kh5 Qh3+ 53.Kg5 Qh6+ 54.Kg4 (54.Kf5 Rf6+ 55.Ke5 Qf4+ 56.Kd5 Rd6+ 57.Kc5 Qd4+ 58.Kb5 Rb6+ 59.Ka5 Qb4#) 54...Rd4+ 55.Kg3 Qh4+ 56.Kg2 Rg4+ 57.Qxg4 Qxg4+ 58.Kf2 Qd4+ 59.Kg2 a5-+.

51...Qf6+ 52.Ke4 Rd4# 0-1

Maybe you will find this ending both informative and entertaining.

13 May 2022

The Critical Position

In "Surprisingly Strong Move", I briefly described a situation where a move I played in desperation proved winning in all lines. The opportunity was made possible by an error in an equal position. As we had both been shuffling rooks and kings for twenty moves, it was not an easy matter for my opponent to discern that a critical position had been reached.

Black to move
Black played 52...Kd6.

Both 52...Rg1 and 52...Rh1 leave White with an advantage so slight that the game should end as a draw.

a) 52...Rg1 53.f3

Alternately, 53.Ra5+ Kd6 54.f3 seems about the same. 

53...Rb1 54.Ra6 Re1 55.Rb6 and Stockfish thinks 55...Ra1 is best.

b) 52...Rh1 seems slightly worse than Rg1 in the initial engine evaluation. But, the main line continues 53.Ra5 Kd6 54.d5 (else matters don't change) 54...Rh2 55.f3 exd5 56.Rxa6 Kd7 57.Kxf5 and the tablebases indicate draw.

Black to move
Tablebase Draw

12 May 2022

Surprisingly Strong Move

In mid-April, I played a move that was better than I thought. I played it in desperation because I was frustrated after reaching what looked like a drawn ending from what seemed like a clear advantage. It was a ten minute game and it sent me to my endgame books as well as extensive engine analysis.

Pawns were exchanged on move 33 and we shuffled our kings and rooks for another 20 moves before I pushed a pawn.

White to move

I expected 53...exd5 54.Kxf5 and maybe I can do something with my f-pawn. But I also thought that would still likely lead to a draw.


I was sure this move was an error. It equalizes material, but now Black's king gets cut off.

54.Rd2+ Kc6

I easily won Black's pawns. The rooks came off the board on move 77 and my opponent resigned two moves later.

To my surprise, the engines evaluate 53...Kxd5 as no worse than 53...exd5. That sent me into the endgame books to study rook endings with two pawns to one, three pawns to two, and four pawns to three. Such positions are often drawn.

Catching my eye as suitable for practice was a tragicomedy from Hebden -- Wood, Hastings 1994/1995.

Black to move
Wood's move here resembles what I thought to be an error in my game.


Mark Dvoretsky writes, "A terrible error. The black king will be cut off along the f-file now, and the g7-pawn will be inevitably lost" (Dvoretsky's Endgame Manual, 5th ed. [2020], 189).

Dvoretsky gives two ways to draw. I opted for the harder one against Stockfish on the iPad.

1...g6 2.Rf7+ Ke4 3.Kg4 Ra1 4.Re7+ Kd5

White to move
My king is cut off from the pawns, but White's king has no points for penetration. Nine moves later, Stockfish moved the rook from the e-file, allowing my king to return. Another dozen moves and I offered a chance for the engine to force the exchange of rooks. My confidence that I could draw the pawn ending was grounded upon extensive practice with a pawn ending from Dvoretsky (see "Opposition and Outflanking").

White to move
Stockfish did not opt for 22.Re2+ Rxe2 23.Kxe2 Ke6, which I knew to be drawn. Ten moves more of rook shuffling, and Stockfish pushed a pawn.

Black to move
A Philidor position seems likely, but instead the game concluded with a rook exchange that left lone kings. It was good practice. My play was not error free, but one can also back up against a machine.

Reuben Fine, Basic Chess Endings (1941) offers positions where the weaker side's king is cut off from the pawns. No. 390b is presented without a diagram. No game is referenced, although the pawn structure is close to No. 390 (Saemisch -- Spelmann, Teplitz-Schoenau 1922) with colors reversed. Fine claims that White wins No. 390b (Saemisch was able to hold a draw because his king was with the pawns), according to Fine. Stockfish does not agree.

Black to move

Stockfish gives 1...Kd6 2.f5 Ra3+ 3.Kf4 Kd7 and better for White by less than a pawn, usually an indication that the game is headed towards a draw.

2.f5 Ra7 3.g5 Kd6 4.h4

Stockfish recommends 4.Re8

4...Ra4 5.Re1

Black to move

A common idea in such positions, but wrong according to Stockfish.

5...Re3+ 6.Kg4 Kd7 and the engine sees Black holding the position. White's Re8 is not possible.


White will give up the f-pawn for both of Black's pawns after Rg8.