Difficult test suites

[Ajedrecista]

Hello Peter:

[d]1k5r/pPpP2p1/P1P3P1/8/8/Qp6/1P6/K6N w - - 3 17

That's reached from two versions of a study from 1937 by T.Gorgiev.

https://www.yacpdb.org/#search/MWsxcjRc ... MS8xLzA=/1

and

https://www.yacpdb.org/#search/MWsxcjRc ... LzEvMS8w/1

From both of them, from one after 2 and from the other one after 3 moves the position of the diagram's reached, regards

Good find! PDB has got the second version of YACPDB (YACPDB #290653) in its database (PDB P1296195) with unknown source and apparently a wrong year (1931 instead of 1937), but points to a reprint that I found:

• Gaudium 111 (August 11th, 2011) (The reprint given by PDB with the problem Nr. 612 and solution, unknown source, apparently wrong year and asking help to find the source).

• Gaudium 112 (September 7th, 2011) (Thanking information from two readers, both pointing to 1937 instead of 1931, but giving two different magazines: Schackvärlden and Revista de Romana de Sah, claiming that 1931 is still widely seen on the Internet).

Schackvärlden was a Swedish magazine (photo of a 1937 issue here, showing 'Göteborg' and 'Stockholm') and Revista Română de Șah (the correct spelling) was a Romanian magazine. I would say that one of the given sources is an early reprint of the other.

Regards from Spain.

Ajedrecista.

[Jouni]

In diagram best move

Analysis by The Huntsman 1:

17.Qf8+ Rxf8 18.Nf2 Rg8 19.Nh3 Rh8 20.Kb1 Rf8 21.Nf4 Rh8 22.Nh5 Rf8 23.Nf6 gxf6 24.g7 Rg8 25.Kc1 f5 26.Kd1 f4 27.Ke2 Rd8 28.Kf3 Rg8 29.Kxf4 Rd8 30.Ke4 Rg8 31.Kd5 Rd8 32.Kc4 Rg8 33.Kxb3 Rd8 34.Kc4 Rg8 35.b4 Rd8 36.b5 Rg8 37.Kd5 Rd8 38.Ke6 Rg8 39.b6 axb6 40.Kf7 Rd8 41.g8Q Rxg8 42.Kxg8 Ka7 43.d8Q Kxa6 44.Qd5 b5 45.b8Q Ka5 46.Qdxb5#
+- (#30) Depth: 103/60 00:00:04 57917kN, tb=1432397

In original study
[d]1k1r4/pPpP2p1/P1P3P1/5N2/8/Qp6/1P5p/K7 w - - 0 1

Analysis by Stockfish 18:

17.Ng3 h1Q+ 18.Nxh1 Rh8 19.Qf8+ Rxf8 20.Nf2 Rh8 21.Nh3 Rf8 22.Nf4 Rh8 23.Nh5 Rf8 24.Nf6 gxf6 25.Kb1 f5 26.Kc1 f4 27.Kd2 Rd8 28.g7 Rg8 29.Kd3 Rd8 30.Ke4 Rg8 31.Kf3 Rd8 32.Kxf4 Rg8 33.Ke4 Rd8 34.Kd3 Rg8 35.Kc3 Rd8 36.Kxb3 Rg8 37.Kc4 Rd8 38.Kd5 Rg8 39.Ke6 Rd8 40.b4 Rg8 41.b5 Rd8 42.Kf7 Rg8 43.b6 cxb6 44.Kxg8 Kc7 45.b8Q+ Kxc6 46.d8Q Kc5 47.Qd3 Kb4 48.Qbd6+ Ka4 49.Q6a3#
+- (#33) Depth: 7/66 00:00:00 10kN

[Damir]

[d]7K/P1p1p1p1/2P1P1Pk/6pP/3p2P1/1P6/3P4/8 w - - 5 55

[Damir]

What is the winning move for White?

[cc2150dx]

[d]7K/P1p1p1p1/2P1P1Pk/6pP/3p2P1/1P6/3P4/8 w - - 5 55

FEN: 7K/P1p1p1p1/2P1P1Pk/6pP/3p2P1/1P6/3P4/8 w - - 5 55

Stockfish-windows-x86-64-avx2:
Found 145 WDL and 145 DTZ tablebase files (up to 5-man).
Available processors: 0-11
Using 6 threads
NNUE evaluation using nn-f68ec79f0fe3.nnue (106MiB, (83248, 1024, 31, 32, 1))
NNUE evaluation using nn-47fc8b7fff06.nnue (6MiB, (22528, 128, 15, 32, 1))
Network replica 1: Shared memory.

245/20 00:00 181k 233k +M10 1.a8N d3 2.Nb6 cxb6 3.c7 b5 4.c8N b4 5.Nd6 exd6 6.e7 d5 7.e8N d4 8.Nf6 gxf6 9.g7 f5 10.g8N+

[peter]

https://www.yacpdb.org/#search/N0tcL1Ax ... LzEvMA==/1

[Ajedrecista]

Hello Peter:

https://www.yacpdb.org/#search/N0tcL1Ax ... LzEvMA==/1

Wow! It is hard to see that the problem of 1986 won a prize instead of being a reprint of the problem of 1936. The problem of 1951 is also a mirror from the original problem.

I searched and found the original sources of the problems of 1936 and 1951, with their printed solutions. I did not even bother to search the original source of the problem of 1986.

------------

To be fair, the problem of 1936 was published as 'Black selfhelpmates in 10' instead of 'White mates in 10':

• (Problem No. 2454) https://www.theproblemist.org/pdf/fcr/vol_3/FCR_040.pdf (The Fairy Chess Review Vol. 3, No. 2, October 1936. Page 17, right column).

• (Solution) https://www.theproblemist.org/pdf/fcr/vol_3/FCR_041.pdf (The Fairy Chess Review Vol. 3, No. 3, December 1936. Page 25, left column).

The comment in the solution is '[...] 2454 is sound if we call it a mate in 10'. So, there was a correction in the stipulation of the problem after a cook was found in the solution.

------------

The problem of 1951 was published as '10#':

• (Problem No. 8132) https://www.dieschwalbe.de/hefte/band06 ... I_1951.pdf (Die Schwalbe No. 216, August, 1951. Page 207, right problem at the top of the page).

• (Solution) https://www.dieschwalbe.de/hefte/band06 ... I_1952.pdf (Die Schwalbe No. 221-222, January-February 1952. Page 300, third solution of the page).

The solution notes that this problem was preceded by the problem of 1936.

Regards from Spain.

Ajedrecista.

[peter]

[Damir]

[d]8/qp6/p7/pk6/2R5/P2K4/8/8 w - - 1 1

[Damir]

White to move: Win/ Draw or Lost