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Subject: Re: Huge Bug in Fritz 9 (Engine)

Author: Drexel,Michael

Date: 11:30:05 10/18/05

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On October 18, 2005 at 12:37:47, George Tsavdaris wrote:

>On October 18, 2005 at 12:11:56, Drexel,Michael wrote:
>
>>[D]1n1r3k/1p1n4/2p5/8/3B4/8/4K3/R7 b - - 0 1
>>This is not supposed to be the Giveaway chess engine :)
>>
>>The endless number of Bugs in the GUI are not worth mentioning of course.
>
>Good discovery! The bug seems to be deeper i suspect, since Fritz 8 (i haven't
>analysed with 9 because i don't have it) evaluates black's position as slightly
>better -actually as almost drawish) even after Kg8 or Kh7.

My Fritz 8 (8.0026) has no problem at all:

1n1r3k/1p1n4/2p5/8/3B4/8/4K3/R7 b - - 0 1

Analysis by Fritz 8:

5...Kh7 6.Kd3 c5 7.Th1+ Kg6 8.Tg1+ Kf5 9.Tf1+ Ke6 10.Te1+ Kd5
  -+  (-4.18)   Depth: 7/18   00:00:00  53kN
5...Kh7 6.Kd3 c5 7.Le3 Se5+ 8.Kc2 Sa6 9.Th1+ Kg6 10.Lf4
  -+  (-4.28)   Depth: 8/19   00:00:00  195kN
5...Kh7 6.Kd3 c5 7.Lb2 Se5+ 8.Ke4 Sd3 9.Lf6 Td6 10.Lc3
  -+  (-4.34)   Depth: 9/25   00:00:00  525kN
5...Kh7 6.Kd3 c5 7.Lb2 Se5+ 8.Kc2 Sbc6 9.Lxe5 Sxe5 10.Te1 Sc6 11.Kc3
  -+  (-4.28)   Depth: 10/28   00:00:00  997kN
5...Kh7 6.Kd3 c5 7.Lb2 Se5+ 8.Ke4 Sc4 9.Th1+ Kg6 10.Tg1+ Kf7 11.Tg7+ Ke6 12.Tg6+
Kd7 13.Lc3
  -+  (-4.43)   Depth: 11/41   00:00:02  2951kN
5...Kh7 6.Kd3 c5 7.Lb2 Se5+ 8.Kc2 Sd3 9.Th1+ Kg6 10.Tg1+ Kf5 11.Tf1+ Ke4 12.Lf6
Tc8 13.Kc3 c4
  -+  (-4.47)   Depth: 12/39   00:00:06  7664kN
5...Kh7 6.Kd3 b5 7.Kc3 c5 8.Le3 Te8 9.Th1+ Kg7 10.Tg1+ Kf7 11.Lxc5 Sxc5
  -+  (-4.50)   Depth: 13/45   00:00:22  26161kN
5...Kg8!
  -+  (-4.53)   Depth: 13/45   00:00:35  41905kN

> So i suspect Fritz 9 would evaluate Kg8 or Kh7 as around 0.38 so it plays Ne5
>as this looks to Fritz as drawish too. That means it doesn't understand the
>position. What if you force the moves 1...Kh7 2.Rh1+ Kg6 3.Rg1+ Kf7 4.Rf1+ Ke6
>+-
>Does Fritz 9 shows now a big advantage for black? If my suspicions are correct
>and with a comparison with F8 evaluation, i believe that even in this position
>that occured, Fritz 9 will believe that it is still a draw.
>
> So now Frans Morsch has to try to understand what is the "problem" behind this
>position, because as such position exists, there may be (many) others with the
>same bad behaviour for Fritz 9 and this is the actual problem.....

Of course there are many other such positions.

For example:
[D]3r3k/2pp4/1pn5/8/8/8/4KB2/R7 w - - 0 5

Black has a nice endgame.

Analysis by Fritz 9:

5.Kd2 Tg8 6.Kc3 Tg2 7.Ta2 Kh7 8.Kc4 Se5+
  -+  (-2.43)   Depth: 7/18   00:00:00  84kN
5.Lg3!
  -+  (-2.42)   Depth: 7/18   00:00:00  96kN
5.Lg3 d6 6.Tc1 Sd4+ 7.Kd3 c5
  -+  (-2.33)   Depth: 7/18   00:00:00  103kN
5.Lg3 Te8+ 6.Kd2 Se5 7.Kc3 d6 8.Ta2 c5 9.Th2+ Kg7 10.Tg2
  -+  (-2.52)   Depth: 8/21   00:00:00  228kN
5.Kd2!
  -+  (-2.52)   Depth: 8/22   00:00:00  343kN
5.Kd2!
  -+  (-2.36)   Depth: 8/22   00:00:00  365kN
5.Kd2 Tg8 6.Th1+ Kg7
  -+  (-2.34)   Depth: 8/22   00:00:00  388kN
5.Kd2 Tg8 6.Th1+ Kg7 7.Tg1+ Kf7 8.Txg8 Kxg8 9.Kc3 d6 10.Kc4 Se5+ 11.Kc3
  -+  (-2.44)   Depth: 9/21   00:00:00  523kN
5.Kd2 Se5 6.Th1+ Kg7 7.Kc3 c5 8.Tg1+ Kf7 9.Tf1
  -+  (-2.54)   Depth: 10/24   00:00:01  1670kN
5.Lg3!
  -+  (-2.53)   Depth: 10/31   00:00:02  2300kN
5.Lg3 d6 6.Tc1 Sd4+ 7.Kd3 c5 8.Lh4 Tb8 9.Lf6+ Kh7 10.Lxd4 cxd4 11.Tc7+ Kg6
12.Kxd4
  -+  (-2.44)   Depth: 10/31   00:00:02  2491kN
5.Lg3 d6 6.Tc1 Sd4+ 7.Kd3 c5 8.Lh4 Tb8 9.Lf6+ Kh7 10.Lxd4 cxd4 11.Tc7+ Kg6
12.Kxd4
  -+  (-2.44)   Depth: 11/35   00:00:04  4756kN
5.Lg3 Tc8 6.Tc1 Kg7 7.Kd3 Ta8 8.Lxc7
  -+  (-2.48)   Depth: 12/40   00:00:10  13079kN
5.Lg3 Tc8 6.Tc1 Kg7 7.Kd3 Kf7 8.Kd2 Ke6 9.Te1+ Kd5 10.Kc3 d6 11.Td1+ Ke6
  -+  (-2.48)   Depth: 13/48   00:00:23  29996kN
5.Lg3 Tc8 6.Tc1 Kg7 7.Kd3 Kf7 8.Kc4 d6 9.Kd5 Se7+ 10.Kc4 Tg8 11.Lf4 Sg6
  -+  (-2.56)   Depth: 14/49   00:00:55  72318kN

You would think it is even better to have an extra bishop in the position:

[D]3r3k/2pp1b2/1pn5/8/8/8/4KB2/R7 w - - 0 5

Analysis by Fritz 9:

5.Kd2 Sd4 6.Ta6 Te8 7.Lg3 Te2+ 8.Kd1 d6
  µ  (-0.80)   Depth: 7/18   00:00:00  183kN
5.Kd2 Sd4 6.Ta7 Sb5 7.Ta6 d5 8.Le3 d4
  µ  (-0.82)   Depth: 8/20   00:00:00  348kN
5.Kd2 Sd4 6.Ta7 c5 7.Le3 b5 8.Kd3 Kg7 9.Tb7
  µ  (-0.86)   Depth: 9/22   00:00:00  878kN
5.Kd2 Se5 6.Ta7 Sc4+ 7.Kc3 c5 8.Lg3 d5 9.Tb7 Kh7 10.Lf4
  µ  (-0.90)   Depth: 10/24   00:00:03  3253kN
5.Kd2 Se5 6.Ta7 Sc4+ 7.Kc3 c5 8.Lh4 d5 9.Tb7 Kg7 10.Lg5 Kg6
  µ  (-0.94)   Depth: 11/26   00:00:07  8182kN
5.Kd2 Se5 6.Lg3 c5 7.Lf4 d5 8.Ta7 Kh7 9.Tb7 Tb8 10.Tc7 Kg6
  µ  (-0.99)   Depth: 12/35   00:00:25  29673kN

Surprise,surprise
Now the position is rather drawish.
We humans can still learn a lot from the silicon monsters ;)

Michael

>After 1...Kh7 2.Rh1+ Kg6 3.Rg1+ Kf7 4.Rf1+ Ke6 +-
>[D]1n1r4/1p1n4/2p1k3/8/3B4/8/4K3/5R2 w - - 0 5
>
>>
>>Michael



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