Not logged inRybka Chess Community Forum
Forum RybkaChess Help Search Register Login
Up Topic Rybka Support & Discussion / Rybka Discussion / Rybka 3 doesn't see knight under promotion
- - By Fishpov (*) [fr] Date 2009-08-19 00:43
In this position
8/5p2/5P1P/pp1p1P2/3P4/kp6/1p1P4/1K6 w - - 0 9


Rybka plays h7 or d3 with evaluation  draw.
Rybka did not see : 1 h7 a4 - 2 h8 (Knight promotion) b4 - 3 Cg6 !

Is it a rybka bug ?
Parent - - By Dadi Jonsson (Silver) [is] Date 2009-08-19 07:41
It seems that Rybka doesn't find it. I tried up to depth 42.

Since I was testing these kind of positions in IDeA, I had it analyze this position with Rybka 3 1-cpu. It found the knight promotion and a mating score in a few seconds.
Parent - By ernest (****) [fr] Date 2009-08-19 10:37
Very curious: on  my Core 2 Duo, only with MaxCPUs=1 does Rybka 3 32-bit find it!

Is it another form of the EGTB bug? (but the workaround doesn't help, here...)
Parent - By Permanent Brain (*****) Date 2009-08-19 19:43
But a guess R3 finds 10. (2. but your FEN start with move no. 9) h8N after h7 b4?

8/5p1P/5P2/p2p1P2/1p1P4/kp6/1p1P4/1K6 w - - 0 10


Analysis by Rybka 2.3.2a 32-bit :

10.h8N a4 11.Ng6 fxg6 12.f7 gxf5 13.f8Q f4 14.Qf7 f3 15.Qxf3
  +-  (6.07)   Depth: 9   00:00:00  1kN
  +-  (18.01)   Depth: 13   00:00:05  629kN
- By Fishpov (*) [fr] Date 2009-08-19 11:46
You're right.
With only one cpu it is working.
I think the problem may be bad transfer information between process or thread core.
I don't forget that rybka is always not able to under promote with bishop and the under promote knight was not here on the first Rybka releases.
Up Topic Rybka Support & Discussion / Rybka Discussion / Rybka 3 doesn't see knight under promotion

Powered by mwForum 2.27.4 © 1999-2012 Markus Wichitill