Author: Dan Newman
Date: 03:33:37 10/06/99
Go up one level in this thread
On October 05, 1999 at 12:26:17, Robert Hyatt wrote:
>On October 05, 1999 at 11:06:03, blass uri wrote:
>
>>On October 05, 1999 at 10:51:29, Robert Hyatt wrote:
>><snipped>
>>>On October 05, 1999 at 04:14:13, blass uri wrote:
>>>
>>>>On October 04, 1999 at 22:37:48, Robert Hyatt wrote:
>>>>
>>>>>On October 04, 1999 at 20:33:35, blass uri wrote:
>>
>>>>>>The relevant position is:
>>>>>>
>>>>>>7k/4K2p/7P/3p4/8/4Q3/1q6/8 w - - 0 1
>>>>>>
>>>>>>The first evaluation above 0 of Fritz5 is +5.16 pawns for white
>>>>>>I do not believe that it can be explained by positional compensation.
>>>>>>
>>>>>>If it is because of a bug then Fritz3 and Fritz4 have the same bug(I do not know
>>>>>>if Fritz5.32 shows similiar behaviour)
>>>>>>
>>>>>>Uri
>>>>>
>>>>>
>>>>>are you sure this is the position? This seems to be a mate in 8 according
>>>>>to my PII/300 notebook (crafty):
>>>>>
>>>>> 9 4.89 0.48 1. Ke6 Qa1 2. Kd7 Qa4+ 3. Kd6 Qb4+
>>>>> 4. Kxd5 Qb7+ 5. Kc4 Qa6+ 6. Kb4 Qd6+
>>>>> 7. Kb5 Qd5+ 8. Kb4 <HT>
>>>>> 9-> 7.46 0.48 1. Ke6 Qa1 2. Kd7 Qa4+ 3. Kd6 Qb4+
>>>>> 4. Kxd5 Qb7+ 5. Kc4 Qa6+ 6. Kb4 Qd6+
>>>>> 7. Kb5 Qd5+ 8. Kb4 <HT>
>>>>> 10 8.27 ++ 1. Ke6!!
>>>>> 10 12.34 Mat08 1. Ke6 Qa1 2. Qb6 Qe1+ 3. Kd7 Kg8 4.
>>>>> Qf6 Qg3 5. Qe6+ Kh8 6. Qe8+ Qg8 7.
>>>>> Qe5+ <HT>
>>>>> 10-> 18.59 Mat08 1. Ke6 Qa1 2. Qb6 Qe1+ 3. Kd7 Kg8 4.
>>>>> Qf6 Qg3 5. Qe6+ Kh8 6. Qe8+ Qg8 7.
>>>>> Qe5+ Qg7+ 8. Qxg7# <HT>
>>>>> 11 23.23 Mat08 1. Ke6 Qa1 2. Qb6 Qe1+ 3. Kd7 Kg8 4.
>>>>> Qf6 Qg3 5. Qe6+ Kh8 6. Qe8+ Qg8 7.
>>>>> Qe5+ Qg7+ 8. Qxg7#
>>>>> 11-> 36.33 Mat08 1. Ke6 Qa1 2. Qb6 Qe1+ 3. Kd7 Kg8 4.
>>>>> Qf6 Qg3 5. Qe6+ Kh8 6. Qe8+ Qg8 7.
>>>>> Qe5+ Qg7+ 8. Qxg7#
>>>>> 12 50.03 Mat08 1. Ke6 Qa1 2. Qb6 Qe1+ 3. Kd7 Kg8 4.
>>>>> Qf6 Qg3 5. Qe6+ Kh8 6. Qe8+ Qg8 7.
>>>>> Qe5+ Qg7+ 8. Qxg7#
>>>>
>>>>I am sure that it is the position and I believe that the reason that Fritz
>>>>cannot see the mate is that it is a null move problem for Fritz.
>>>>1.Ke6 threats nothing.
>>>>
>>>>Try the position after Ke6 with white to move.
>>>>
>>>>Uri
>>>
>>>
>>>I get this:
>>>
>>> 9 5.01 -Mat07 1. ... Qa1 2. Qb6 Qe1+ 3. Kd7 Kg8 4.
>>> Qf6 Qg3 5. Qe6+ Kh8 6. Qe8+ Qg8 7.
>>> Qe5+ Qg7+ 8. Qxg7# <HT>
>>> 9-> 6.13 -Mat07 1. ... Qa1 2. Qb6 Qe1+ 3. Kd7 Kg8 4.
>>> Qf6 Qg3 5. Qe6+ Kh8 6. Qe8+ Qg8 7.
>>> Qe5+ Qg7+ 8. Qxg7# <HT>
>>> 10 11.37 -Mat07 1. ... Qa1 2. Qb6 Qe1+ 3. Kd7 Kg8 4.
>>> Qf6 Qg3 5. Qe6+ Kh8 6. Qe8+ Qg8 7.
>>> Qe5+ Qg7+ 8. Qxg7#
>>> 10-> 11.76 -Mat07 1. ... Qa1 2. Qb6 Qe1+ 3. Kd7 Kg8 4.
>>> Qf6 Qg3 5. Qe6+ Kh8 6. Qe8+ Qg8 7.
>>> Qe5+ Qg7+ 8. Qxg7#
>>> 11 24.97 -Mat07 1. ... Qa1 2. Qb6 Qe1+ 3. Kd7 Kg8 4.
>>> Qf6 Qg3 5. Qe6+ Kh8 6. Qe8+ Qg8 7.
>>> Qe5+ Qg7+ 8. Qxg7#
>>> 11-> 25.92 -Mat07 1. ... Qa1 2. Qb6 Qe1+ 3. Kd7 Kg8 4.
>>> Qf6 Qg3 5. Qe6+ Kh8 6. Qe8+ Qg8 7.
>>> Qe5+ Qg7+ 8. Qxg7#
>>>
>>>although it is certainly possible that small differences in the two programs
>>>can cause interesting null-move behavior...
>>
>>Fritz can also see mate against itsealf after Ke6 but the point is that ke6
>>threats nothing so Fritz cannot see the mate before Ke6.
>>
>>
>>You can prove it by analyzing the position after Ke6 with *white* to move.
>>
>>Uri
>
>
>With white to move, it reaches a tablebase draw score instantly, meaning
>black is zugzwanged... Although I don't see why Fritz would miss the mate.
>I tried it on my quad xeon and I find the mate instantly even though I have all
>the existing tablebase files on this box, so that null move could quickly screw
>up with that 'draw' score returned after a null at ply=2.
Here's a run of my program Skyblue on a P6/200 with null move turned on:
6. -7 0.44 27348 Kd6 Qb4+ Kxd5 Qb7+ Ke5 Qf7 Qh3 Kg8
6> -7 0.55 40364 Kd6 Qb4+ Kxd5 Qb7+ Ke5 Qf7 Qh3 Kg8
7. -7 0.72 58899 Kd6 Qb4+ Kxd5 Qb7+ Ke5 Qb8+ Kd4 Qd8+ Ke4 Kg8
Qd4
7> -7 1.05 105697 Kd6 Qb4+ Kxd5 Qb7+ Ke5 Qb8+ Kd4 Qd8+ Ke4 Kg8
Qd4
8. -7 1.42 161829 Kd6 Qb4+ Kxd5 Qb7+ Ke5 Qb8+ Kd4 Qd8+ Ke4 Qe8+
Kd4 Qxe3+ Kxe3 Kg8 Kd4
8> -7 3.02 368776 Kd6 Qb4+ Kxd5 Qb7+ Ke5 Qb8+ Kd4 Qd8+ Ke4 Qe8+
Kd4 Qxe3+ Kxe3 Kg8 Kd4
9. -7 4.07 518752 Kd6 Qb4+ Kxd5 Qb7+ Ke5 Qb8+ Kd4 Qd8+ Ke4 Qe8+
Kd4 Qxe3+ Kxe3 Kg8 Kd4 Kh8
9. 0 10.38 1382701 Qf4 Qb7+ Ke8 Qc6+ Ke7 Qb7+ <TPR draw>
9> 0 10.82 1459411 Qf4 Qb7+ Ke8 Qc6+ Ke7 Qb7+ <TPR draw>
10. 0 12.31 1704858 Qf4 Qb7+ Ke8 Qc6+ Ke7 Qb7+ <TPR draw>
10> 0 14.72 2107062 Qf4 Qb7+ Ke8 Qc6+ Ke7 Qb7+ <TPR draw>
11. 0 18.78 2776881 Qf4 Qb7+ Ke8 Qc6+ Ke7 Qb7+ <TPR draw>
11> 0 24.06 3677158 Qf4 Qb7+ Ke8 Qc6+ Ke7 Qb7+ <TPR draw>
12. 0 33.39 5264064 Qf4 Qb7+ Ke8 Qc6+ Ke7 Qb7+ <TPR draw>
12> 0 43.60 7022910 Qf4 Qb7+ Ke8 Qc6+ Ke7 Qb7+ <TPR draw>
13. 0 1:09 11431291 Qf4 Qb7+ Ke8 Qc6+ Ke7 Qb7+ <TPR draw>
13> 0 1:31 15234044 Qf4 Qb7+ Ke8 Qc6+ Ke7 Qb7+ <TPR draw>
Here it is with null move off:
6. -7 0.54 34526 Kd6 Qb4+ Kxd5 Qb7+ Ke5 Qb8+ Kd4 Kg8 Qe5
6> -7 0.82 68732 Kd6 Qb4+ Kxd5 Qb7+ Ke5 Qb8+ Kd4 Kg8 Qe5
7. -7 1.04 101081 Kd6 Qb4+ Kxd5 Qb7+ Ke5 Qb8+ Kd4 Qd8+ Ke4 Kg8
Qd4
7. 0 1.26 126478 Ke6 Qa1 Ke7 Qb2 Ke6 <TPR draw>
7> 0 1.75 196352 Ke6 Qa1 Ke7 Qb2 Ke6 <TPR draw>
8. 0 2.03 235454 Ke6 Qa1 Ke7 Qb2 Ke6 <TPR draw>
8> 0 3.51 463732 Ke6 Qa1 Ke7 Qb2 Ke6 <TPR draw>
9. 0 4.33 585858 Ke6 Qa1 Ke7 Qb2 Ke6 <TPR draw>
9> 0 7.79 1145268 Ke6 Qa1 Ke7 Qb2 Ke6 <TPR draw>
10+ 100 9.06 1339642 Ke6
10> +mate8 10.87 1718339 Ke6 Qa1 Qb6 Qe1+ Kd7 Kg8 Qf6 Qg3 Qe6+ Kh8
Qe8+ Qg8 Qe5+ Qg7+ Qxg7+ <Checkmate>
So, it appears to be a null move problem of some sort in my program.
Perhaps if I let it run longer...
Interesting problem, I'll have to study it.
-Dan.
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.