A mate in 3 that engines cannot solve ? WOW!

[Robert Flesher]

[d] 8/1n3Np1/1N4Q1/1bkP4/p1p2p2/P1P2R2/3P2PK/B2R4 w - - 0 0

[AdminX]

[d] 8/1n3Np1/1N4Q1/1bkP4/p1p2p2/P1P2R2/3P2PK/B2R4 w - - 0 0

Which engine can't solve it?

Analysis by Bright-0.4a3:

1.Rh1 Be8 2.Qb1 Bxf7 3.Qb4#
+- (#3) Depth: 6/21 00:00:00 58kN
+- (#3) Depth: 120/21 00:00:00 326kN


Analysis by Onno-1-1-1:

1.Rh1 Be8 2.Qb1 Bxf7 3.Qb4#
+- (#3) Depth: 127/127 00:00:01 267kN
+- (#3) Depth: 127/127 00:00:02 269kN


Analysis by Crafty 23.00:

1.Rxf4 Be8 2.Nxc4 Kxd5 3.Nb6+ Kc5 4.Rf5#
+- (31.32) Depth: 3/11 00:00:00 1kN
+- (#4) Depth: 9/19 00:00:00 2790kN

1.Rh1 Be8 2.Qb1 Bxf7 3.Qb4#
+- (#3) Depth: 9/21 00:00:02 1768kN
+- (#3) Depth: 10/21 00:00:04 17554kN


Analysis by Loop 13.6:

1.Rh1 Be8 2.Qb1 Bxf7 3.Qb4#
+- (#3) Depth: 6 00:00:00 32kN
+- (#3) Depth: 50 00:00:05 33762kN

[Robert Flesher]

[d] 8/1n3Np1/1N4Q1/1bkP4/p1p2p2/P1P2R2/3P2PK/B2R4 w - - 0 0

Which engine can't solve it?

Analysis by Bright-0.4a3:

1.Rh1 Be8 2.Qb1 Bxf7 3.Qb4#
+- (#3) Depth: 6/21 00:00:00 58kN
+- (#3) Depth: 120/21 00:00:00 326kN


Analysis by Onno-1-1-1:

1.Rh1 Be8 2.Qb1 Bxf7 3.Qb4#
+- (#3) Depth: 127/127 00:00:01 267kN
+- (#3) Depth: 127/127 00:00:02 269kN


Analysis by Crafty 23.00:

1.Rxf4 Be8 2.Nxc4 Kxd5 3.Nb6+ Kc5 4.Rf5#
+- (31.32) Depth: 3/11 00:00:00 1kN
+- (#4) Depth: 9/19 00:00:00 2790kN

1.Rh1 Be8 2.Qb1 Bxf7 3.Qb4#
+- (#3) Depth: 9/21 00:00:02 1768kN
+- (#3) Depth: 10/21 00:00:04 17554kN


Analysis by Loop 13.6:

1.Rh1 Be8 2.Qb1 Bxf7 3.Qb4#
+- (#3) Depth: 6 00:00:00 32kN
+- (#3) Depth: 50 00:00:05 33762kN

I guess I should say to tough for SOME engines. Correct Rh1!! brilliant move. Rybka, Hiarcs, Junior, and Zappa fail to see the mate in 3. This is of course in a reasonable amount of time, it is only a mate in 3 after all. So I did not let them search for more than 2-3 min.

[Sean Evans]

Summers turn-off your endgame tablebases

[kgburcham]

I guess I should say to tough for SOME engines. Correct Rh1!! brilliant move. Rybka, Hiarcs, Junior, and Zappa fail to see the mate in 3. This is of course in a reasonable amount of time, it is only a mate in 3 after all. So I did not let them search for more than 2-3 min.

Quick enough for me. "Correct" enough for me.

[D] 8/1n3Np1/1N4Q1/1bkP4/p1p2p2/P1P2R2/3P2PK/B2R4 w - - 0 1


Zappa Mexico II:

1.Rh1 Be8 2.Qb1 Bxf7 3.Qb4#
+- (#3) Depth: 63/47 00:00:00 664kN
1.Rh1 Be8 2.Qb1 Bxf7 3.Qb4#
+- (#3) Depth: 63/47 00:00:00 671kN


Deep Fritz 11:

1.Rxf4 Be8 2.Nxc4 Bd7 3.Qb6+ Kxd5 4.Rd4#
+- (#4) Depth: 7/19 00:00:00 106kN


Deep Junior 7:

1.Nxc4
+- (20.16) Depth: 6 00:00:00 15kN
1.Nxc4 Nd6 2.Qxd6+ Kxc4 3.d3+ Kb3 4.Qb4+ Ka2 5.Rf2#
+- (#5) Depth: 6 00:00:00 24kN
1.Nxc4 Nd6 2.Qxd6+ Kxc4 3.d3+ Kb3 4.Qb4+ Ka2 5.Rf2#
+- (#5) Depth: 6 00:00:00 33kN


Rybka 3:

1.Rxf4
+- (#5) Depth: 6 00:00:00 3kN
1.Rxf4
+- (#6) Depth: 7 00:00:00 7kN
1.Rxf4
+- (#4) Depth: 8 00:00:00 39kN
1.Rxf4
+- (#4) Depth: 9 00:00:03 3024kN

[plattyaj]

Zungwang in there I guess ... still, at least in this test position if an engine doesn't see the mate in three it probably gets it in four so it won't lose. That's the mate Schola finds unless shown Rh1:

Code: Select all

6 2938 45 183852 Rxf4 Be8 Rxc4+ Kb5 Rb4+ Ka6 Nc8+ Bc6 dxc6
7 3038 45 184094 Rxf4 ++
7 3338 45 188060 Rxf4 ++
7 32757 46 203029 Rxf4 Be8 Rxc4+ Kb5 Rb1+ Ka6 Nc8+ Nd6 Qxd6+ Ka5 Qb6#
7 32761 109 860171 Na8 Kxd5 Qb6 Bd7 Nc7+ Ke4 Qb1#

Andy.

[kgburcham]

Two attractive mates.


[D] 8/1n3Np1/1N6/1bkP4/p1p2p2/P1PQ1R2/3P2PK/B2R4 b - - 0 1


1...cxd3 2.Rb1 Na5 3.c4 Nb3 4.Rxb3 axb3 5.cxb5 b2 6.Bxb2 Kxb5 7.d6 Kxb6 8.d7 Ka6 9.d8Q g5 10.Qc8+ Kb6 11.Rxd3 Ka5 12.Rd5+ Kb6 13.Bd4#
+- (#12) Depth: 15/49 00:00:13 52023kN

[zullil]

[d] 8/1n3Np1/1N4Q1/1bkP4/p1p2p2/P1P2R2/3P2PK/B2R4 w - - 0 0

I thought this seemed familiar. This appears as Diagram 37 in "How to Get More out of Chess" by Fred Reinfeld. Reinfeld attributes the problem to Frank Healey, and claims it appeared in the Bristol Tournament of 1861. For this reason, the clearance theme used to solve this problem is called the "Bristol theme."

[Dann Corbit]

[d] 8/1n3Np1/1N4Q1/1bkP4/p1p2p2/P1P2R2/3P2PK/B2R4 w - - 0 0

Did the engines that you tried which failed to find a solution also fail to find any mate?

P.S.
Chest output:
8/1n3Np1/1N4Q1/1bkP4/p1p2p2/P1P2R2/3P2PK/B2R4 w - - acn 3361; acs 0; bm Rh1; ce 32762; dm 3; pv Rh1 Bd7 Qb1 g6 Qb4#;

[Norm Pollock]

[d] 8/1n3Np1/1N4Q1/1bkP4/p1p2p2/P1P2R2/3P2PK/B2R4 w - - 0 0

I wonder how many GMs could find the move Rh1.

1- It forces the bishop to move to d7 or e8 (Ba6 and Bc6 lead to mate in one so the only feasible B moves are Bd7 and Be8) and any move by the knight leads to mate in one;

2- The movement of the black bishop allows Qb1 which threatens mate from two future moves: Qb4 and Qg1. The second threat is only possible because of Rh1, which moved the rook out of the path b1-g1.

With 2 threats of impending mate, the bishop can only block one:
B-e8 then Bxf7 blocks the mate from g1
and B-b5 blocks the mate from b4

R-h1 is one fantastic move.