Rybka don't find mat in 4?

[jpqy]

The most other chess engines find this mat in 4 around 00:00!!

How about Rybka 3?

MAT in 4!!

8/8/8/1p2Q3/1k6/1p6/1p6/bK6 w - - 0 7

JP.

[AdminX]

The most other chess engines find this mat in 4 around 00:00!!

How about Rybka 3?

MAT in 4!!

8/8/8/1p2Q3/1k6/1p6/1p6/bK6 w - - 0 7

JP.

Human sees it right away, but Default has problems. Dyanmic does a little better, but still not there either.

Analysis by Rybka 3 Human :

1.Qd4+ Ka5 2.Qe4 Ka6 3.Qe6+ Ka5 4.Qxb3 Kb6 5.Qd5 Ka5 6.Qe4 Kb6 7.Qd3 Ka5
+- (4.30) Depth: 2 00:00:00
+- (4.79) Depth: 13 00:00:00 19kN, tb=2

1.Qc7
+- (5.11) Depth: 13 00:00:00 21kN, tb=3
+- (#4) Depth: 13 00:00:00 103kN, tb=5


Analysis by Rybka 3 :

1.Qd4+
+- (4.78) Depth: 2 00:00:00
+- (#27) Depth: 17 00:01:06 18607kN, tb=732


Analysis by Rybka 3 Dynamic :

1.Qd5 Ka5 2.Qd4 Ka6 3.Qd8 b4 4.Qg5 Kb6
+- (3.19) Depth: 2 00:00:00
+- (4.89) Depth: 14 00:00:00 28kN, tb=4

1.Qd4+
+- (5.09) Depth: 14 00:00:00 32kN, tb=5
+- (#6) Depth: 14 00:00:03 824kN, tb=5

[jpqy]

Thanks Ted!

Have you restart your Gui every time you change engine?
Because else the next engine will find the calculatings back in his Hash!

Kind regards,
Jean-Paul.

[AdminX]

Thanks Ted!

Have you restart your Gui every time you change engine?
Because else the next engine will find the calculatings back in his Hash!

Kind regards,
Jean-Paul.

Wow, when I did as you suggested NONE of the Rybka's found it.
Analysis by Rybka 3 Dynamic :

1.Qd5 Ka5 2.Qd4 Ka6 3.Qe3 Ka5 4.Qxb3 Ka6 5.Qd3 Ka5 6.Qe4
+- (3.67) Depth: 2 00:00:00
+- (4.36) Depth: 13 00:00:00 10kN, tb=1

1.Qd4+
+- (4.56) Depth: 13 00:00:00 10kN, tb=1
+- (209.16) Depth: 13 00:00:00 86kN, tb=2


Analysis by Rybka 3 :

1.Qd4+
+- (4.78) Depth: 2 00:00:00
+- (5.71) Depth: 16 00:00:13 3641kN, tb=169


Analysis by Rybka 3 Human :

1.Qd4+
+- (4.48) Depth: 4 00:00:00
+- (#26) Depth: 19 00:01:22 24093kN, tb=842

[plattyaj]

The most other chess engines find this mat in 4 around 00:00!!

How about Rybka 3?

MAT in 4!!

8/8/8/1p2Q3/1k6/1p6/1p6/bK6 w - - 0 7

JP.

Interesting position. I haven't looked why yet but Schola doesn't find it either until shown Qc7! - and then it takes to ply 18 to see it. Perhaps there's something that the null move cutoff is tripping up over.

Andy.

[zullil]

[D] 8/8/8/1p2Q3/1k6/1p6/1p6/bK6 w - - 0 7

[plattyaj]

Interesting position. I haven't looked why yet but Schola doesn't find it either until shown Qc7! - and then it takes to ply 18 to see it. Perhaps there's something that the null move cutoff is tripping up over.

Andy.

Yup - null move it is. And it "trips" up my Zungwang code because of that Bishop. Although it can't move, it's material score (plus the three pawns) brings it above the value of a Rook which is one of the things I use to determine when not to try it.

Interestingly, given the threads about why Rybka doesn't give full PVs, accurate node counts, etc., this probably tells us that Rybka doesn't do verified null move and that it still allows null move with that amount of material on the board. So all I have to do to beat it is ...

Andy.

[Albert Silver]

The most other chess engines find this mat in 4 around 00:00!!

How about Rybka 3?

MAT in 4!!

8/8/8/1p2Q3/1k6/1p6/1p6/bK6 w - - 0 7

JP.

Takes a few seconds, but it finds it:

Analysis by Rybka 3 1-cpu 32-bit:

1.Qd4+ Ka5 2.Qe4 b4 3.Qd3
+- (5.02) Depth: 6 00:00:00 1kN
1.Qd4+ Ka5 2.Qe4 b4 3.Qd3 Kb6
+- (5.07) Depth: 7 00:00:00 2kN
1.Qd4+ Ka5[] 2.Qe4 Kb6 3.Qb4 Kc6[] 4.Qxb3 Kc5 5.Qc3+
+- (5.03) Depth: 8 00:00:00 12kN
1.Qd4+ Ka5[] 2.Qe4 Kb6 3.Qb4 Kc6[] 4.Qxb3 Kc5 5.Qc3+
+- (5.03) Depth: 9 00:00:00 13kN
1.Qd4+ Ka5[] 2.Qe4 Kb6 3.Qb4 Kc6[] 4.Qxb3 Kc5 5.Qc3+
+- (5.03) Depth: 10 00:00:00 14kN
1.Qd4+ Ka5[] 2.Qe4 Kb6 3.Qb4 Kc6[] 4.Qxb3 Kc5 5.Qc3+ Kb6[]
+- (5.03) Depth: 11 00:00:00 15kN
1.Qd4+ Ka5[] 2.Qe4 Kb6 3.Qb4 Kc6[] 4.Qxb3 Kc5 5.Qc3+ Kb6[] 6.Qd4+
+- (5.03) Depth: 12 00:00:00 18kN
1.Qd4+ Ka5[] 2.Qe4 Kb6 3.Qb4 Kc6[] 4.Qxb3 Kc5 5.Qc3+ Kb6[] 6.Qd4+ Ka5[] 7.Qd6
+- (5.03) Depth: 13 00:00:00 22kN
1.Qc7
+- (#4) Depth: 13 00:00:27 2678kN

(Silver, Private 11.08.2008)

[Philippe]

The most other chess engines find this mat in 4 around 00:00!!

How about Rybka 3?

MAT in 4!!

8/8/8/1p2Q3/1k6/1p6/1p6/bK6 w - - 0 7

JP.

Whit to move. Analysis from Rybka 3.

[Jim Logan]

Interesting yes ... I can always solve as above using Single Processor version, but not with Multiprocessor version; at least not using multi-core. Have not tried setting the MC version to using only 1 core.