A brute force searcher will die even worse because the branching factor of this position increases with depth. Here is a perft
Code: Select all
1 22
2 562
3 18082
4 631076
5 25142756
Vlad.
Moderators: bob, hgm, Harvey Williamson
Code: Select all
1 22
2 562
3 18082
4 631076
5 25142756
slightly different twist -Dann Corbit wrote:[d]qqqqkqqq/qqqqqqqq/qqqqqqqq/qqqqqqqq/QQQQQQQQ/QQQQQQQQ/QQQQQQQQ/QQQQKQQQ w - -
What do you mean it's not a real chess position? I want to see it analyzed.
So far, every engine has crashed instantly except Rybka of all the engines that I tried, but Rybka refused to utter a single syllable after 15 mintues of thought. I think the slimy fish knows the answer, but he's not telling just to spite me.
Code: Select all
White(1): g
time surplus 0.00 time limit 30:00 (+0.00) (30:00)
depth time score variation (1)
1 13.11 12.68 1. Qaxf7+ (4.4Mnps)
1-> 13.14 12.68 1. Qaxf7+ (4.4Mnps)
2 13.14 12.68 1. Qaxf7+ Qxf7 2. Qcxh7
2-> 13.17 12.68 1. Qaxf7+ Qxf7 2. Qcxh7
3 13.19 12.68 1. Qaxf7+ Qxf7 2. Qcxh7
3-> 13.20 12.68 1. Qaxf7+ Qxf7 2. Qcxh7
4 13.22 +1 1. Qaxf7+!
4 13.22 +3 1. Qaxf7+!
4 13.22 +M 1. Qaxf7+!
4 13.22 Mat04 1. Qaxf7+ Qxf7 2. Qh8+ Qxh8 3. Qxh8+
Qf8 4. Qhxf8#
4-> 13.25 Mat04 1. Qaxf7+ Qxf7 2. Qh8+ Qxh8 3. Qxh8+
Qf8 4. Qhxf8#
5 13.25 Mat04 1. Qaxf7+ Qxf7 2. Qh8+ Qxh8 3. Qxh8+
Qf8 4. Qgg6#
5-> 13.26 Mat04 1. Qaxf7+ Qxf7 2. Qh8+ Qxh8 3. Qxh8+
Qf8 4. Qgg6#
6 13.28 Mat04 1. Qaxf7+ Qxf7 2. Qh8+ Qxh8 3. Qxh8+
Qf8 4. Qgg6#
6-> 13.30 Mat04 1. Qaxf7+ Qxf7 2. Qh8+ Qxh8 3. Qxh8+
Qf8 4. Qgg6#
7 13.31 Mat04 1. Qaxf7+ Qxf7 2. Qh8+ Qxh8 3. Qxh8+
Qf8 4. Qgg6#
7-> 13.34 Mat04 1. Qaxf7+ Qxf7 2. Qh8+ Qxh8 3. Qxh8+
Qf8 4. Qgg6#
time=13.36 mat=0 n=58429045 fh=98% nps=4.4M
extensions=566 qchecks=10K reduced=959 pruned=18K
predicted=0 evals=64K 50move=0 EGTBprobes=0 hits=0
SMP-> splits=0 aborts=0 data=0/256 elap=13.36
mate in 4 moves.
White(1): Qaxf7+
time used: 13.36
Black(1):
Chesspartner 5.4 did not collapse, but after ten plus minutes is sticking with its pick made at around two minutesDann Corbit wrote:[d]qqqqkqqq/qqqqqqqq/qqqqqqqq/qqqqqqqq/QQQQQQQQ/QQQQQQQQ/QQQQQQQQ/QQQQKQQQ w - -
What do you mean it's not a real chess position? I want to see it analyzed.
So far, every engine has crashed instantly except Rybka of all the engines that I tried, but Rybka refused to utter a single syllable after 15 mintues of thought. I think the slimy fish knows the answer, but he's not telling just to spite me.
Why it is not possible???MikeB wrote: The position is not possibe from a real game of chess - but Crafty sees the 8+1 queens on both sides and is happy to oblige.
Wouldn't the last move have had to have been a pawn promoting to a queen, in which case the square from which it had moved would be empty?Milos wrote:Why it is not possible???MikeB wrote: The position is not possibe from a real game of chess - but Crafty sees the 8+1 queens on both sides and is happy to oblige.
It's quite possible, it's however highly improbable.
IMHO we are talking _legal_ chess positions. Which means no more than 8 white or black pawns, no more than 9 white or black queens, no more than 10 white or black knights, bishops and rooks, and total pawns + total pieces <= 16.George Tsavdaris wrote:A reasonable Chess program i guess you mean, because a reasonable general program for Chess variations should produce analysis.bob wrote: Crafty won't crash. But it will produce the correct error messages:
illegal position, too many white queens
illegal position, too many white pieces
illegal position, too many black queens
illegal position, too many black pieces
bad string = "qqqqkqqq/qqqqqqqq/qqqqqqqq/qqqqqqqq/QQQQQQQQ/QQQQQQQQ/QQQQQQQQ/QQQQKQQQ"
Illegal position, using normal initial chess position
Which is what a reasonable program ought to produce.
But as you put it, a reasonable Chess program should also produce an error message for the above position too. Does Crafty produces it or analyzes the position?
If the latter happens then Crafty is selective in analyzing non-Chess positions. and i guess the latter happens.
So instead of being selective in what positions to analyze it should just analyze them all, if the board is 8x8 and the pieces are all Chess pieces.
At least i find this better behavior than being selective.
[d]5r2/2k1p3/1bnp4/2p2N2/p3KP2/6P1/P1P5/1B2R3 w - - 0 1
All I try to do is to verify that the position appears legal to a cursory look, by counting total pieces and pawns. To be strictly correct, a position must be reachable from the starting position, which is beyond computationally tractable.zullil wrote:Crafty finds this impossible position acceptable:George Tsavdaris wrote: But as you put it, a reasonable Chess program should also produce an error message for the above position too. Does Crafty produces it or analyzes the position?
[d]5r2/2k1p3/1bnp4/2p2N2/p3KP2/6P1/P1P5/1B2R3 w - - 0 1
Code: Select all
Crafty v23.4 (16 cpus) White(1): setboard 5r2/2k1p3/1bnp4/2p2N2/p3KP2/6P1/P1P5/1B2R3 w - - 0 1 White(1): st 180 search time set to 180.00. White(1): display +---+---+---+---+---+---+---+---+ 8 | | . | | . | |<R>| | . | +---+---+---+---+---+---+---+---+ 7 | . | |<K>| |<P>| | . | | +---+---+---+---+---+---+---+---+ 6 | |<B>|<N>|<P>| | . | | . | +---+---+---+---+---+---+---+---+ 5 | . | |<P>| | . |-N-| . | | +---+---+---+---+---+---+---+---+ 4 |<P>| . | | . |-K-|-P-| | . | +---+---+---+---+---+---+---+---+ 3 | . | | . | | . | |-P-| | +---+---+---+---+---+---+---+---+ 2 |-P-| . |-P-| . | | . | | . | +---+---+---+---+---+---+---+---+ 1 | . |-B-| . | |-R-| | . | | +---+---+---+---+---+---+---+---+ a b c d e f g h White(1): display stats display statistics at end of each search. White(1): go time limit 3:00 (+0.00) (3:00) depth time score variation (1) starting thread 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 <done> 11-> 0.06 0.42 1. Ne3 e6 2. c4 Rh8 3. g4 Nd4 4. g5 Ba5 5. Rd1 Rh2 6. g6 12 0.09 0.38 1. Ne3 e6 2. c4 Nd4 3. Rh1 Kc6 4. Rh7 Ba5 5. Bd3 Rb8 6. g4 Rb2 12-> 0.09 0.38 1. Ne3 e6 2. c4 Nd4 3. Rh1 Kc6 4. Rh7 Ba5 5. Bd3 Rb8 6. g4 Rb2 13 0.11 0.25 1. Ne3 e6 2. c4 Nd4 3. Rh1 Kc6 4. Rh7 Ba5 5. Bd3 Rb8 6. g4 Rb2 7. a3 13-> 0.12 0.25 1. Ne3 e6 2. c4 Nd4 3. Rh1 Kc6 4. Rh7 Ba5 5. Bd3 Rb8 6. g4 Rb2 7. a3 (s=2) 14 0.16 0.35 1. Ne3 e6 2. c4 Nd4 3. Rh1 Kc6 4. Rh7 Ba5 5. Bd3 Rb8 6. g4 Rb2 7. Ra7 Kb6 14-> 0.18 0.35 1. Ne3 e6 2. c4 Nd4 3. Rh1 Kc6 4. Rh7 Ba5 5. Bd3 Rb8 6. g4 Rb2 7. Ra7 Kb6 15 0.24 0.15 1. Ne3 e6 2. c4 Nd4 3. Rh1 Kc6 4. Rh7 Bc7 5. Bd3 Rb8 6. f5 exf5+ 7. Nxf5 Rb2 8. Nxd4+ cxd4 15-> 0.32 0.15 1. Ne3 e6 2. c4 Nd4 3. Rh1 Kc6 4. Rh7 Bc7 5. Bd3 Rb8 6. f5 exf5+ 7. Nxf5 Rb2 8. Nxd4+ cxd4 (s=2) 16 0.45 0.00 1. Ne3 e6 2. c4 Nd4 3. Rh1 Kc6 4. Rh7 Bc7 5. Bd3 Rb8 6. Nc2 Rb2 7. Nxd4+ cxd4 8. g4 e5 16 0.86 0.33 1. c3 Ba5 2. Re3 e6 3. Ng7 Kd7 4. g4 Bc7 5. Kf3 Ne5+ 6. Kg3 Rf7 7. fxe5 Rxg7 8. exd6 Bxd6+ 9. Kf3 Rf7+ 10. Ke4 16-> 0.89 0.33 1. c3 Ba5 2. Re3 e6 3. Ng7 Kd7 4. g4 Bc7 5. Kf3 Ne5+ 6. Kg3 Rf7 7. fxe5 Rxg7 8. exd6 Bxd6+ 9. Kf3 Rf7+ 10. Ke4 17 1.04 0.24 1. c3 Ba5 2. Re3 e6 3. Ng7 Kd7 4. g4 Bc7 5. f5 d5+ 6. Kf3 Ne5+ 7. Ke2 exf5 8. Bxf5+ Kd6 9. Ne6 Rf7 10. Nxc7 Rxc7 17-> 1.12 0.24 1. c3 Ba5 2. Re3 e6 3. Ng7 Kd7 4. g4 Bc7 5. f5 d5+ 6. Kf3 Ne5+ 7. Ke2 exf5 8. Bxf5+ Kd6 9. Ne6 Rf7 10. Nxc7 Rxc7 18 1.37 0.02 1. c3 Ba5 2. Re3 e6 3. Ng7 Kd7 4. g4 Bc7 5. Kf3 Ne5+ 6. Kg3 Nxg4 7. Kxg4 Rg8 8. Rxe6 Rxg7+ 9. Rg6 Rxg6+ 10. Bxg6 18-> 2.20 0.02 1. c3 Ba5 2. Re3 e6 3. Ng7 Kd7 4. g4 Bc7 5. Kf3 Ne5+ 6. Kg3 Nxg4 7. Kxg4 Rg8 8. Rxe6 Rxg7+ 9. Rg6 Rxg6+ 10. Bxg6 (s=4) 19 2.56 0.11 1. c3 Ba5 2. Re3 e6 3. Ng7 Kd7 4. Kf3 Ne5+ 5. Ke2 Ng4 6. Rxe6 Bxc3 7. Rg6 Nf6 8. Bc2 a3 9. Kd3 Bd4 10. Ba4+ Ke7 11. Nf5+ Kf7 (s=3) 19-> 3.28 0.11 1. c3 Ba5 2. Re3 e6 3. Ng7 Kd7 4. Kf3 Ne5+ 5. Ke2 Ng4 6. Rxe6 Bxc3 7. Rg6 Nf6 8. Bc2 a3 9. Kd3 Bd4 10. Ba4+ Ke7 11. Nf5+ Kf7 (s=3) 20 4.34 0.14 1. c3 Ba5 2. Re3 e6 3. Ng7 Kd7 4. Kf3 Ne5+ 5. Ke2 Rb8 6. Bc2 Ng4 7. Re4 Rb2 8. Kd2 Rxa2 9. Rxa4 Rxa4 10. Bxa4+ Ke7 11. Kd3 (s=2) 20-> 5.22 0.14 1. c3 Ba5 2. Re3 e6 3. Ng7 Kd7 4. Kf3 Ne5+ 5. Ke2 Rb8 6. Bc2 Ng4 7. Re4 Rb2 8. Kd2 Rxa2 9. Rxa4 Rxa4 10. Bxa4+ Ke7 11. Kd3 21 9.28 0.06 1. c3 Ba5 2. Re3 Kd7 3. g4 e6 4. Ng7 Bc7 5. Kf3 Ne5+ 6. Kg3 Nxg4 7. Kxg4 Rg8 8. Rxe6 Rxg7+ 9. Rg6 Rxg6+ 10. Bxg6 Ke6 11. c4 Kf6 21 20.10 0.33 1. c4 e6 2. Ne3 Nd4 3. Rh1 Kc6 4. Rh6 Ba5 5. Bd3 Be1 6. Rg6 Bf2 7. Nc2 Re8 8. Nxd4+ cxd4 9. g4 Re7 10. Rg8 Rh7 11. Rc8+ Kb6 21-> 20.79 0.33 1. c4 e6 2. Ne3 Nd4 3. Rh1 Kc6 4. Rh6 Ba5 5. Bd3 Be1 6. Rg6 Bf2 7. Nc2 Re8 8. Nxd4+ cxd4 9. g4 Re7 10. Rg8 Rh7 11. Rc8+ Kb6 (s=3) 22 25.17 0.36 1. c4 e6 2. Ne3 Nd4 3. Rh1 Ba5 4. Bd3 Rb8 5. g4 Kc6 6. Nc2 d5+ 7. Ke3 Bc3 8. Nxd4+ Bxd4+ 9. Kf3 Rb2 10. Rh6 Kd7 11. a3 Rf2+ 12. Kg3 Rb2 13. Rh7+ Kd6 (s=2) 22-> 27.35 0.36 1. c4 e6 2. Ne3 Nd4 3. Rh1 Ba5 4. Bd3 Rb8 5. g4 Kc6 6. Nc2 d5+ 7. Ke3 Bc3 8. Nxd4+ Bxd4+ 9. Kf3 Rb2 10. Rh6 Kd7 11. a3 Rf2+ 12. Kg3 Rb2 13. Rh7+ Kd6 23 34.03 0.39 1. c4 e6 2. Ne3 Nd4 3. Rh1 Ba5 4. Bd3 Rb8 5. g4 Kc6 6. f5 exf5+ 7. gxf5 Rb2 8. f6 Rxa2 9. f7 Ne6 10. Rh5 Rb2 11. Nd1 Rg2 12. Ne3 23-> 36.94 0.39 1. c4 e6 2. Ne3 Nd4 3. Rh1 Ba5 4. Bd3 Rb8 5. g4 Kc6 6. f5 exf5+ 7. gxf5 Rb2 8. f6 Rxa2 9. f7 Ne6 10. Rh5 Rb2 11. Nd1 Rg2 12. Ne3 24 45.77 0.19 1. c4 e6 2. Ne3 Nd4 3. Rh1 Ba5 4. Nc2 Ne2 5. Kf3 Nc3 6. Ne3 Nxb1 7. Rxb1 Kc6 8. g4 Rh8 9. g5 Bd2 10. Ke4 Bxe3 11. Kxe3 Rh3+ 12. Ke4 Rc3 13. f5 Rxc4+ 14. Kd3 24-> 53.60 0.19 1. c4 e6 2. Ne3 Nd4 3. Rh1 Ba5 4. Nc2 Ne2 5. Kf3 Nc3 6. Ne3 Nxb1 7. Rxb1 Kc6 8. g4 Rh8 9. g5 Bd2 10. Ke4 Bxe3 11. Kxe3 Rh3+ 12. Ke4 Rc3 13. f5 Rxc4+ 14. Kd3 25 1:05 0.19 1. c4 e6 2. Ne3 Nd4 3. Rh1 Ba5 4. Nc2 Ne2 5. Kf3 Nc3 6. Ne3 Nxb1 7. Rxb1 Kc6 8. g4 Bc3 9. Ke4 Rh8 10. Rc1 Bd4 11. g5 Bxe3 12. Kxe3 Rh2 13. Ra1 25-> 1:16 0.19 1. c4 e6 2. Ne3 Nd4 3. Rh1 Ba5 4. Nc2 Ne2 5. Kf3 Nc3 6. Ne3 Nxb1 7. Rxb1 Kc6 8. g4 Bc3 9. Ke4 Rh8 10. Rc1 Bd4 11. g5 Bxe3 12. Kxe3 Rh2 13. Ra1 26 1:58 0.33 1. c4 e6 2. Ne3 Nd4 3. Rh1 Ba5 4. Bd3 Rb8 5. Rh7+ Kc6 6. Ra7 Bc7 7. Ra6+ Kb7 8. Rxa4 Kc6 9. Nc2 Rg8 10. Nxd4+ cxd4 11. Kf3 e5 12. Rb4 Rh8 13. a4 Rh2 14. Rb5 Ra2 15. Be4+ Kd7 26-> 2:18 0.33 1. c4 e6 2. Ne3 Nd4 3. Rh1 Ba5 4. Bd3 Rb8 5. Rh7+ Kc6 6. Ra7 Bc7 7. Ra6+ Kb7 8. Rxa4 Kc6 9. Nc2 Rg8 10. Nxd4+ cxd4 11. Kf3 e5 12. Rb4 Rh8 13. a4 Rh2 14. Rb5 Ra2 15. Be4+ Kd7 time=3:00 mat=0 n=4141454327 fh=89% nps=23.0M extensions=99.8M qchecks=247.2M reduced=407.2M pruned=767.2M predicted=0 evals=1707.5M 50move=0 EGTBprobes=1K hits=1K SMP-> splits=351522 aborts=52237 data=91/1024 elap=3:00 terminating SMP processes. White(1): c4 time used: 3:00 Black(1): quit