Test the combinational vision of your engine

[Scally]

I’m guessing a slight typo ...

Bxh7+ is the winning move

Al.

[zullil]

When I was checking the line after 1...Be7 2.Bxe7 Bc6 3.Bd6 Qxc7 4.Bxc7 O-O, I found a weakness in Stockfish, unable to find quickly the sacrifice to mate : Bxf7+!

[d]1r3rk1/1pB2ppp/2b1p3/3pP3/p4Q2/P2B4/1P3PPP/2R3K1 w - - 1 5

Stockfish only searches legal moves.

In any case, Stockfish-dev finds Bxh7+ in just seconds:

info depth 31 seldepth 42 multipv 1 score cp 1734 lowerbound nodes 170694422 nps 48520301 hashfull 547 tbhits 0 time 3518 pv d3h7

[yurikvelo]

My SF prefer Bxb8 from D=1 to D=34 (2+ BN nodes).
Eval is +17.15 @ D31, +32.39 @ D32, +61.4 @ D33

Even after 5. Bxh7+ it takes a while to resolve +M

28- 174 481k +32,28 5. ... Kxh7
28+ 174 518k +88,33 5. ... Kxh7 6.Bxb8
28- 174 959k +47,31 5. ... Kxh7
28- 175 546k +32,07 5. ... Kxh7
28+ 175 569k +M50 5. ... Kxh7 6.Bxb8
28+ 187 935k +M22 5. ... Kxh7 6.Bxb8 d4
29+ 207 094k +M21 5. ... Kxh7 6.Bxb8 d4
30+ 219 151k +M19 5. ... Kxh7 6.Bxb8 Rxb8
31+ 248 420k +M12 5. ... Kxh7 6.Rc3 f6
32+ 253 112k +M12 5. ... Kxh7 6.Rc3 f6
33+ 258 005k +M11 5. ... Kxh7 6.Rc3 f6

Good engine is not DTM-solver, good engine is a game winner

[Uri Blass]

a very poor combinational vision by stockfish.

extremely good combinational vision by stockfish lead it it other combinational winning lines with very fast evel raise.

Stockfish is not DTM-solver, there is no elo-bonus in tournaments for shortest-DTM lines

To claim "poor vision" you have to provide position in which engine cannot win fast or win at all (or loose in drawing position)

Qf4 line lead to Queen material win in 5 moves

5 moves are a lot when you have many variations.
Humans who solve this problem are supposed to find Rxd7 Kxd7 Qa7 that win material.

[yurikvelo]

BTW

+M12 5.Bxb8 h6 6.Bd6 Re8 7.Qh4 Rc8 8.Be7 Rc7 9.Bf6 Kf8 10.Qg3 g5 11.Qg4 b5 12.Bh7 Ke8 13.Qb4 Rd7 14.Rxc6 Rb7 15.Qf8+ Kxf8 16.Rc8#

+M12 5.Bxh7+ Kxh7 6.Rc3 f6 7.Bxb8 Kg8 8.Rg3 f5 9.Bd6 Rf7 10.Rh3 Rf8 11.Qg5 Rc8 12.Rg3 Rc7 13.Bxc7 Kf7 14.Qxg7+ Ke8 15.Qh8+ Kf7 16.Rg7#

it took D=54 to resolve 5.Bxb8 as +M12

[MikeB]

BTW

+M12 5.Bxb8 h6 6.Bd6 Re8 7.Qh4 Rc8 8.Be7 Rc7 9.Bf6 Kf8 10.Qg3 g5 11.Qg4 b5 12.Bh7 Ke8 13.Qb4 Rd7 14.Rxc6 Rb7 15.Qf8+ Kxf8 16.Rc8#

+M12 5.Bxh7+ Kxh7 6.Rc3 f6 7.Bxb8 Kg8 8.Rg3 f5 9.Bd6 Rf7 10.Rh3 Rf8 11.Qg5 Rc8 12.Rg3 Rc7 13.Bxc7 Kf7 14.Qxg7+ Ke8 15.Qh8+ Kf7 16.Rg7#

it took D=54 to resolve 5.Bxb8 as +M12

I'm working on a new sibling engine to "McCain", which will be named "1st-Mate". It is based on current dev- Stockfish, Matefinder code by Joe Ellis, and McCain.

Source will soon be released. Mate finding engines are always good to have in your tool box.

[d]1r3rk1/1pB2ppp/2b1p3/3pP3/p4Q2/P2B4/1P3PPP/2R3K1 w - - 1 5

info depth 30 seldepth 30 multipv 1 score mate 12 nodes 643713295 nps 33205060 hashfull 972 tbhits 0 time 19386 pv d3h7 g8h7 c1c3 f7f6 c7b8 f6f5 c3h3 h7g8 f4h4 f8b8 h4h8 g8f7 h8b8 c6d7 b8b7 f7g6 h3g3 g6h6 b7d7 g7g6 d7f7 h6h5 f7h7

[Dann Corbit]

I will be interested to see how long it takes to prove that this is a mate in 13:
[d]8/2P1P3/1PnKnP2/1ppbpp2/1BPbPB2/2NkN3/3P4/8 w - -

As you can see from the seconds field in the analysis version of the record below, it took quite a while to solve it the last time I tried (several years ago and both hardware and software have advanced a lot). Still, I expect to get the mate down to 13 will take a while. I believe that I used Chest319, which is very slow on mates of more than 8, but when it does solve it proves a minimum unless you use special features to prune the search.

8/2P1P3/1PnKnP2/1ppbpp2/1BPbPB2/2NkN3/3P4/8 w - - acd 27; acs 28682; bm e8=Q; dm 13; ce 32742; dm 13; pm e8=Q; pv e8=Q cxb4 cxd5 Nxf4 Qxc6 bxc3 Qxb5+ Kxd2 Nf1+ Kd1 c8=Q Ke1 Qb1+ Kf2 Qxf5 Bc5+ Kxc5 c2 Qxc2+ Kxf1 Qg4 Ne6+ dxe6 Ke1 Qge2+;

Original post from 2016:
http://talkchess.com/forum3/viewtopic.p ... F3P4%2F8+w

[Dann Corbit]

I will be interested to see how long it takes to prove that this is a mate in 13:
[d]8/2P1P3/1PnKnP2/1ppbpp2/1BPbPB2/2NkN3/3P4/8 w - -

As you can see from the seconds field in the analysis version of the record below, it took quite a while to solve it the last time I tried (several years ago and both hardware and software have advanced a lot). Still, I expect to get the mate down to 13 will take a while. I believe that I used Chest319, which is very slow on mates of more than 8, but when it does solve it proves a minimum unless you use special features to prune the search.

8/2P1P3/1PnKnP2/1ppbpp2/1BPbPB2/2NkN3/3P4/8 w - - acd 27; acs 28682; bm e8=Q; dm 13; ce 32742; dm 13; pm e8=Q; pv e8=Q cxb4 cxd5 Nxf4 Qxc6 bxc3 Qxb5+ Kxd2 Nf1+ Kd1 c8=Q Ke1 Qb1+ Kf2 Qxf5 Bc5+ Kxc5 c2 Qxc2+ Kxf1 Qg4 Ne6+ dxe6 Ke1 Qge2+;

Original post from 2016:
http://talkchess.com/forum3/viewtopic.p ... F3P4%2F8+w

As you can see, it will take SF forever and a day to resolve mate in 13:

Code: Select all

Searching: 8/2P1P3/1PnKnP2/1ppbpp2/1BPbPB2/2NkN3/3P4/8 w - - 0 1
infinite: 0 time: 0 increment: 0 moves to go: 0

 1  +18.25   00:00   12454  f7 cxb4 exd5 bxc3 Kxe6 exf4
 2  +21.22   00:00   59136  e8=Q Nxf4 c8=Q Bxe3 Nxd5
 3  +20.08   00:00  107559  e8=Q Nxc7 bxc7
 4  +20.16   00:00  148017  e8=Q exf4 c8=Q fxe3 Nxd5
 5  +20.59   00:00  185647  e8=Q exf4 Nexd5
 6  +20.99   00:00  228157  e8=Q exf4 c8=Q fxe3 cxd5
 7  +20.18   00:00  272854  e8=Q Nxc7 bxc7 Na7 Ncxd5 cxb4 Bxe5
 8  +20.41   00:00  311097  e8=Q Nxc7 bxc7 Na7 Ncxd5 cxb4 Bxe5
 9  +21.20   00:00  348853  e8=Q Nxf4 c8=Q Bxe4 Nxe4 Nxb4 Qxf5 Bxe3
10  +21.27   00:00  435183  e8=Q exf4 c8=Q fxe3 cxd5 Nxb4 dxe6 exd2 Nd1 Bxf6
11  +21.41   00:00  514511  e8=Q Nxf4 c8=Q Nxb4 Nexd5 Nbxd5 exd5 Bxc3 dxc3
12  +21.59   00:00  630002  e8=Q exf4 c8=Q fxe3 cxd5 Nxb4 dxe6 exd2 Nd1
13  +22.16   00:00   1019K  e8=Q exf4 c8=Q fxe3 cxd5 cxb4 Qcxc6 bxc3 dxe3
14  +22.10   00:00   1546K  e8=Q exf4 c8=Q fxe3 cxd5 cxb4 Qexc6 bxc3 Qxe6 e2 exf5 Kxd2 Qce8
15  +22.81   00:00   2028K  e8=Q exf4 c8=Q fxe3 cxd5 Nxb4 dxe6 exd2 Nd1 Kc2 b7
16  +23.66   00:00   3891K  e8=Q exf4 c8=Q fxe3 cxd5 cxb4 Qexc6 Bxc3 dxc3 e2 b7 e1=Q Qxb5+ Kc2 cxb4+ Kb2 b8=Q
17  +25.17   00:00  14577K  e8=Q Bxc3 c8=Q Bxe4 Bxc3 exf4 Nxf5 Ncd8 f7 b4 f8=Q Nxf8 Qexd8 bxc3 Kxc5+ Kc2 Qxf8
18  +25.92   00:01  20532K  e8=Q exf4 c8=Q Be5+ Kxd5 fxe3 Qcxc6 cxb4 Kxe5 bxc3 Qd5+ Ke2 Qh5+ Kf2 Qxe6 cxd2 Qhxf5+ Ke2 Qg4+ Ke1
19  +26.64   00:02  45951K  e8=Q exf4 c8=Q fxe3 cxd5 cxb4 Qexc6 bxc3 dxe3 Nd8 Qxd8 Kxe3 b7 Kf4 b8=Q Be5+ Kc5 Bxb8 Qxb8+ Kxe4 Kxb5
20  +27.39   00:04  76514K  e8=Q Bxc3 Nxd5 Bxb4 c8=Q Ncd8 Nxb4+ cxb4 b7 Nxb7+ Kxe6 exf4 Qxb7 f3 Qexb5 Kxd2 Kxf5 Kc1
21  +28.44   00:08 133197K  e8=Q exf4 c8=Q fxe3 cxd5 cxb4 Qexc6 Bxc3 dxc3 e2 dxe6 e1=Q b7 Qxe4 Qxe4+ fxe4 b8=Q e3 Qxb5+ Ke4 Qxb4+ Kf3
22  +29.56   00:14 229153K  e8=Q cxb4 Ncxd5 Na7 Qxe6 Bxb6 f7 exf4 Nxb6 fxe3 f8=Q exd2 Qd5+ Kc2 c8=Q Nxc8+ Qxc8 Kd1 cxb5 Ke1 Qc2
23  +30.66   00:31 502948K  e8=Q Nxf4 c8=Q Be6 Qcxc6 cxb4 b7 bxc3 b8=Q cxd2 Nd1 Kc2 exf5 Kxd1 fxe6 Ke2 Qe4+ Be3 Qc2 Ke1 f7
24  +32.28   01:15   1209M  e8=Q Nxf4 c8=Q Be6 Qcxc6 cxb4 b7 bxc3 b8=Q cxd2 Nd1 Kc2 exf5 Kxd1 fxe6 Ke2 Qe4+ Be3 Qc2 Ke1 f7 d1=Q+ Qxd1+ Kxd1 f8=Q Ke2 Qbxb5 Nd3 Qh5+ Kd2 Qff3
25  +33.89   02:39   2522M  e8=Q Bxe4 c8=Q Bxc3 Bxc3 exf4 Nxf5 Ncd8 f7 b4 f8=Q Nxf8 Qexd8 Kc2 Ke5 Bf3 b7 Ng6+ Kf6 bxc3 Ne3+ Kc1 b8=Q fxe3 dxe3 Ne7
26  +35.05   03:55   3704M  e8=Q Nxb4 c8=Q Ng7 fxg7 Bg8 Qxg8 exf4 b7 fxe3 b8=Q e2 Qge6 e1=Q g8=Q Qxd2 Nxb5 Kc2 exf5 Kb2 Nxd4 Qxd4+ Qd5 Qf2 Qcxc5
27  +36.22   09:16   8426M  e8=Q cxb4 Ncxd5 exf4 c8=Q Ncd8 Nxf5 Bc5+ Ke5 Kxd2 b7 f3 b8=Q f2 Ng3 Bd4+ Kf5 Ke1 cxb5 Bc5 Qh5 Kd2 Qe2+ Kc1 Qxf2 Kb1 Qe1+ Ka2 Nxb4+ Kb3
28  +37.79   12:58  11806M  e8=Q Nxb4 c8=Q Bb7 Qxb7 Nxf4 f7 Bxc3 f8=Q Bxd2 Qba8 Kxe3 b7 Nbd3 b8=Q b4 Qxf5 Bc3 Qa2 Nc1 Qh2 Nce2 Kxc5 Nd3+ Kd6 Ndf4 Qb7 Nd3 Qg5+ Ndf4 Qh3+ Kd2 Kc5 Kc2
29  +40.78   29:54  26774M  e8=Q Nxb4 c8=Q Bb7 Qxb7 Nxf4 f7 Bxc3 f8=Q Bxd2 Qba8 Bxe3 b7 Ne2 b8=Q Bd4 Qxf5 Kc2 Qexb5 Nc3 Qf3 Be3 Qba5 Kd2 Qa3 Kd3 Kxe5 Nc2 Qf1+ Kd2 Qab2
30  +42.58   46:22  41577M  e8=Q Nxf4 c8=Q Bf7 Qxf7 Nxb4 b7 Kxd2 Nxf5 Bxc3 b8=Q Nbd3 Qfg8 b4 f7 Kc2 f8=Q Be1 Qc6 Kb3 Qg4 Nb2 Kxc5 Bc3 Qg1 Nfd3+ Kb5 Ne1 Qd5 Kc2 c5 Ned3 Qg2+ Kc1
31  +43.16 1:21:07  73704M  e8=Q Nxf4 c8=Q Bf7 Qxf7 Nxb4 b7 Kxd2 Nxf5 Bxc3 b8=Q Nbd3 Qfg8 b4 f7 Kc2 f8=Q Be1 Qc6 Nb2 Kxc5 Nbd3+ Kb5 Bc3 c5 Kb2 Qc4 Nc1 Qd7 Kc2 Qxe5 Ncd3 Qa2+ Bb2 Qeb8 Ne2 Qc4+ Nc3+ Kb6
32  +45.78 2:07:45 116447M  e8=Q Nxf4 c8=Q Bf7 Qxf7 Nxb4 b7 Kxd2 Nxf5 Bxc3 b8=Q Na2 Qfg8 Bb4 f7 Nc3 f8=Q Kc2 Kxe5 Nce2 Qxb5 Nd3+ Ke6 Kb2 Qf6+ Nc3 Qbd7 Nf4+ Kf7 Ne2 Qd1 Nf4 Qd2+ Kb3 Qxf4 Kxc4
33  +47.32 2:39:05 145043M  e8=Q Nxf4 c8=Q Bf7 Qxf7 Nxb4 b7 Kxd2 Nxf5 Bf2 b8=Q Kxc3 Qfg8 Ne2 f7 Kb3 f8=Q Nc3 cxb5+ Kb2 Qg2 Nd3 Qf3 Kc2 Qe6 Be1 Qc4 Nb2 Qcf1 c4 Q3g2+ Kb1 Qxe1+ Nbd1 Kxe5