Test Position

[zullil]

[d]r1b2rk1/3n1pb1/2p1p1p1/p5P1/Pp2B1NQ/1q4P1/2R2P2/3R2K1 w - - 8 34

This one is surprisingly difficult for Stockfish. See here for more.

Crafty-25.2:

Code: Select all

White(1): go
        time surplus   0.00  time limit 3:00 (3:00)
        depth     time       score   variation (1)
starting thread 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 <done>
         17     1.30/3:00    -1.05   1. Kg2 Re8 2. Nf6+ Kf8 3. Nxd7+ Bxd7
                                     4. Rxd7 Rad8 5. Ra7 Re7 6. Rxa5 Qa3
                                     7. Rxc6 b3 8. Rb6 b2 9. Qh7 Qa1 10. Rc5
                                     Qxa4
         17->   1.31/3:00    -1.05   1. Kg2 Re8 2. Nf6+ Kf8 3. Nxd7+ Bxd7
                                     4. Rxd7 Rad8 5. Ra7 Re7 6. Rxa5 Qa3
                                     7. Rxc6 b3 8. Rb6 b2 9. Qh7 Qa1 10. Rc5
                                     Qxa4
         18     1.47/3:00    -0.96   1. Kg2 Re8 2. Nf6+ Kf8 3. Nxd7+ Bxd7
                                     4. Rxd7 Rad8 5. Rc7 Re7 6. R2xc6 Be5
                                     7. Rc8 Rd7 8. Rxd8+ Rxd8 9. Rc5 Qb2
                                     10. Rxa5 Bd4 11. Qh6+ Ke7
         18->   1.50/3:00    -0.96   1. Kg2 Re8 2. Nf6+ Kf8 3. Nxd7+ Bxd7
                                     4. Rxd7 Rad8 5. Rc7 Re7 6. R2xc6 Be5
                                     7. Rc8 Rd7 8. Rxd8+ Rxd8 9. Rc5 Qb2
                                     10. Rxa5 Bd4 11. Qh6+ Ke7
         19     1.78/3:00    -1.16   1. Kg2 Re8 2. Nf6+ Kf8 3. Nxd7+ Bxd7
                                     4. Rxd7 Rad8 5. Rc7 Re7 6. R2xc6 Be5
                                     7. Rc8 Rd7 8. Rxd8+ Rxd8 9. Rc5 Qb2
                                     10. Rxa5 Bd4 11. Qf4 Qe2
         19->   2.15/3:00    -1.16   1. Kg2 Re8 2. Nf6+ Kf8 3. Nxd7+ Bxd7
                                     4. Rxd7 Rad8 5. Rc7 Re7 6. R2xc6 Be5
                                     7. Rc8 Rd7 8. Rxd8+ Rxd8 9. Rc5 Qb2
                                     10. Rxa5 Bd4 11. Qf4 Qe2
         20     4.23/3:00    -0.65   1. Kg2 f5 2. gxf6 Nxf6 3. Bxg6 Ra7 4. Rh1
                                     Qd5+ 5. f3 b3 6. Nh6+ Bxh6 7. Qxh6 Nh5
                                     8. Rf2 Nf4+ 9. gxf4 Qd4 10. Bh7+ Kf7
                                     11. Re2 Qg7+ 12. Qg5 Qxg5+ 13. fxg5
         20->   4.30/3:00    -0.65   1. Kg2 f5 2. gxf6 Nxf6 3. Bxg6 Ra7 4. Rh1
                                     Qd5+ 5. f3 b3 6. Nh6+ Bxh6 7. Qxh6 Nh5
                                     8. Rf2 Nf4+ 9. gxf4 Qd4 10. Bh7+ Kf7
                                     11. Re2 Qg7+ 12. Qg5 Qxg5+ 13. fxg5
         21     4.87/3:00    -0.50   1. Kg2 f5 2. gxf6 Nxf6 3. Bxg6 Ra7 4. Rh1
                                     Qd5+ 5. f3 b3 6. Nh6+ Bxh6 7. Qxh6 Nh5
                                     8. Rf2 Nf4+ 9. gxf4 Qd4 10. Bh7+ Kf7
                                     11. Qg5 Ke8 12. Bg6+ Kd7 13. Rh7+ Kd6
         21->   4.96/3:00    -0.50   1. Kg2 f5 2. gxf6 Nxf6 3. Bxg6 Ra7 4. Rh1
                                     Qd5+ 5. f3 b3 6. Nh6+ Bxh6 7. Qxh6 Nh5
                                     8. Rf2 Nf4+ 9. gxf4 Qd4 10. Bh7+ Kf7
                                     11. Qg5 Ke8 12. Bg6+ Kd7 13. Rh7+ Kd6
         22     6.12/3:00    -0.45   1. Kg2 f5 2. gxf6 Nxf6 3. Bxg6 Ra7 4. Rh1
                                     Qd5+ 5. f3 b3 6. Nh6+ Bxh6 7. Qxh6 Nh5
                                     8. Rf2 Nf4+ 9. gxf4 Qd4 10. Rh4 b2 11. Be4
                                     Qxe4 12. Rg4+ Kf7 13. Rg7+ Ke8 14. fxe4
                                     Rxg7+
         22->   6.46/3:00    -0.45   1. Kg2 f5 2. gxf6 Nxf6 3. Bxg6 Ra7 4. Rh1
                                     Qd5+ 5. f3 b3 6. Nh6+ Bxh6 7. Qxh6 Nh5
                                     8. Rf2 Nf4+ 9. gxf4 Qd4 10. Rh4 b2 11. Be4
                                     Qxe4 12. Rg4+ Kf7 13. Rg7+ Ke8 14. fxe4
                                     Rxg7+
         23     7.90/3:00    -0.33   1. Kg2 f5 2. gxf6 Nxf6 3. Bxg6 Ra7 4. Rh1
                                     Qd5+ 5. f3 b3 6. Nh6+ Bxh6 7. Qxh6 Nh5
                                     8. Rf2 Nf4+ 9. gxf4 Qd4 10. Qg5 Rd8
                                     11. Rb1 Rd5 12. Bh7+ Kf7 13. Qg8+ Kf6
                                     14. Rxb3 Qxf4
         23->   8.14/3:00    -0.33   1. Kg2 f5 2. gxf6 Nxf6 3. Bxg6 Ra7 4. Rh1
                                     Qd5+ 5. f3 b3 6. Nh6+ Bxh6 7. Qxh6 Nh5
                                     8. Rf2 Nf4+ 9. gxf4 Qd4 10. Qg5 Rd8
                                     11. Rb1 Rd5 12. Bh7+ Kf7 13. Qg8+ Kf6
                                     14. Rxb3 Qxf4
         24    14.11/3:00     0.00   1. Kg2 f5 2. gxf6 Nxf6 3. Bxg6 Ra7 4. Rh1
                                     Qd5+ 5. f3 b3 6. Nh6+ Bxh6 7. Qxh6 Nh5
                                     8. Rf2 Nf4+ 9. gxf4 Qd4 10. Qg5 Rg7
                                     11. Qh5 Ra7 12. Bh7+ Kh8 13. Bg6+ Kg8
                                     <3-fold>
         24->  14.37/3:00     0.00   1. Kg2 f5 2. gxf6 Nxf6 3. Bxg6 Ra7 4. Rh1
                                     Qd5+ 5. f3 b3 6. Nh6+ Bxh6 7. Qxh6 Nh5
                                     8. Rf2 Nf4+ 9. gxf4 Qd4 10. Qg5 Rg7
                                     11. Qh5 Ra7 12. Bh7+ Kh8 13. Bg6+ Kg8
                                     <3-fold>
         25    18.48/3:00     0.00   1. Kg2 f5 2. gxf6 Nxf6 3. Bxg6 Ra7 4. Rh1
                                     Qd5+ 5. f3 Rff7 6. Nh6+ Kf8 7. Nxf7 Rxf7
                                     8. Bxf7 Kxf7 9. Re1 b3 10. Rb2 Nh5
                                     11. Rbb1 c5 12. Red1 Qe5 13. Re1 Qd5
                                     <3-fold>
         25->  19.30/3:00     0.00   1. Kg2 f5 2. gxf6 Nxf6 3. Bxg6 Ra7 4. Rh1
                                     Qd5+ 5. f3 Rff7 6. Nh6+ Kf8 7. Nxf7 Rxf7
                                     8. Bxf7 Kxf7 9. Re1 b3 10. Rb2 Nh5
                                     11. Rbb1 c5 12. Red1 Qe5 13. Re1 Qd5
                                     <3-fold>
         26    23.51/3:00    -0.31   1. Kg2 f5 2. gxf6 Nxf6 3. Bxg6 Ra7 4. Rh1
                                     Qd5+ 5. f3 Rff7 6. Nh6+ Kf8 7. Nxf7 Rxf7
                                     8. Bxf7 Kxf7 9. Re1 Nh5 10. Rce2 Bf6
                                     11. Qh3 Bc3 12. Re5 Nf4+ 13. gxf4 Bxe5
                                     14. Qh5+ Ke7 15. Rxe5 Qa2+ 16. Kg3 Qxa4
                                     17. Rxa5
         26     1:12/3:00     1.43   1. Rxd7 Bxd7 2. Nf6+ Bxf6 3. gxf6 Qb1+
                                     4. Kg2 Qa1 5. Re2 c5 6. Re1 Qe5 7. Bxg6
                                     Bc6+ 8. Kh3 fxg6 9. Rxe5 Kf7 10. Qc4 Bd5
                                     11. Qxc5 Kxf6 12. Qd4 Kf7 13. Re3 Rac8
                                     14. f4 Kg8 15. Kg4
         26->   1:12/3:00     1.43   1. Rxd7 Bxd7 2. Nf6+ Bxf6 3. gxf6 Qb1+
                                     4. Kg2 Qa1 5. Re2 c5 6. Re1 Qe5 7. Bxg6
                                     Bc6+ 8. Kh3 fxg6 9. Rxe5 Kf7 10. Qc4 Bd5
                                     11. Qxc5 Kxf6 12. Qd4 Kf7 13. Re3 Rac8
                                     14. f4 Kg8 15. Kg4 (s=2)
         27     1:17/3:00     1.47   1. Rxd7 Bxd7 2. Nf6+ Bxf6 3. gxf6 Qb1+
                                     4. Kg2 Qa1 5. Re2 c5 6. Re1 Qe5 7. Bxg6
                                     Bc6+ 8. Kh3 fxg6 9. Rxe5 Kf7 10. Qc4 Bd5
                                     11. Qxc5 Kxf6 12. Qd4 Kf7 13. Re3 Kg8
                                     14. f4 Rac8 15. Kg4 Rfd8 (s=2)
         27->   1:18/3:00     1.47   1. Rxd7 Bxd7 2. Nf6+ Bxf6 3. gxf6 Qb1+
                                     4. Kg2 Qa1 5. Re2 c5 6. Re1 Qe5 7. Bxg6
                                     Bc6+ 8. Kh3 fxg6 9. Rxe5 Kf7 10. Qc4 Bd5
                                     11. Qxc5 Kxf6 12. Qd4 Kf7 13. Re3 Kg8
                                     14. f4 Rac8 15. Kg4 Rfd8 (s=2)
         28     2:29/3:00     6.47   1. Rxd7 Bxd7 2. Nf6+ Bxf6 3. gxf6 Qb1+
                                     4. Kg2 Qa1 5. Re2 Qe5 6. Bxg6 fxg6 7. Rxe5
                                     Kf7 8. Qh7+ Kxf6 9. Re4 Rfe8 10. Qxd7 g5
                                     11. Qxc6 Rad8 12. Re3 g4 13. Qb5 e5
                                     14. Qxa5 Rd4 15. Qc5 Re6 16. a5 (s=2)
         28->   2:30/3:00     6.47   1. Rxd7 Bxd7 2. Nf6+ Bxf6 3. gxf6 Qb1+
                                     4. Kg2 Qa1 5. Re2 Qe5 6. Bxg6 fxg6 7. Rxe5
                                     Kf7 8. Qh7+ Kxf6 9. Re4 Rfe8 10. Qxd7 g5
                                     11. Qxc6 Rad8 12. Re3 g4 13. Qb5 e5
                                     14. Qxa5 Rd4 15. Qc5 Re6 16. a5 (s=2)
        time=3:00(97%)  nodes=18079706233(18.1B)  fh1=87%  pred=0  nps=100.3M
        chk=537.4M  qchk=718.9M  fp=7.1B  mcp=1.5B  50move=1
        LMReductions:  1/771.2M  2/2.0M  3/2
        null-move (R):  3/632.1M  4/85.7M  5/2.1M  6/92.1K  7/1.4K
        splits=578.0K(439.0K)  aborts=32.2K  joins=867.7K  data=23%(23%)
White(1): Rxd7
              time used:   3:00

[AndrewGrant]

Ethereal with Syzygy Probe Depth set to 127 (max.), which it doesn't seem to care much about neither

So SyzygyProbeDepth applies to the highest cardinality for the Tablebases.

IE, if you have a 6 man table base setup, If Ethereal probes, then one of the following is true:

1) The current depth is greater than or equal to SyzygyProbeDepth (Setting 127 makes this case never true, essentially)
2) We are actually in a 5 man position. (1 less than highest TB given). Then we probe because we know it will be fast.

This has caused some confusion before. I saw this mentioned on some German chess forums a while back. I believe that
Stockfish does the same thing, but maybe its time I add some UCI options to make it more clear. Something like ...

uci option name SyzygyProbeSmallTables type check default true

[peter]

Thanks a lot for the new version, Andrew!

So SyzygyProbeDepth applies to the highest cardinality for the Tablebases.

IE, if you have a 6 man table base setup, If Ethereal probes, then one of the following is true:

1) The current depth is greater than or equal to SyzygyProbeDepth (Setting 127 makes this case never true, essentially)
2) We are actually in a 5 man position. (1 less than highest TB given). Then we probe because we know it will be fast.

And thanks for trying to explain, but I fear, I'm too stupid for that.
None of the two criteria you give seem to fit to the position in question here and Probe Depth was set to 127, so how come the tbs- hits in our example?

[AndrewGrant]

Thanks a lot for the new version, Andrew!

So SyzygyProbeDepth applies to the highest cardinality for the Tablebases.

IE, if you have a 6 man table base setup, If Ethereal probes, then one of the following is true:

1) The current depth is greater than or equal to SyzygyProbeDepth (Setting 127 makes this case never true, essentially)
2) We are actually in a 5 man position. (1 less than highest TB given). Then we probe because we know it will be fast.

And thanks for trying to explain, but I fear, I'm too stupid for that.
None of the two criteria you give seem to fit to the position in question here and Probe Depth was set to 127, so how come the tbs- hits in our example?

Its not about the root position, its about the positions that get explored.

Somewhere in Ethereal's search, the given position is reduced to a 5 man one, via a serious of (potentially awful) exchanges. This is when criteria #2 is met, and TB hits are occurring.

[peter]

Its not about the root position, its about the positions that get explored.

Somewhere in Ethereal's search, the given position is reduced to a 5 man one, via a serious of (potentially awful) exchanges. This is when criteria #2 is met, and TB hits are occurring.

Now I got it, thanks again.