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Subject: Re: Mate in 7 moves - diagram

Author: Steffen Jakob

Date: 02:31:08 09/28/00

Go up one level in this thread


On September 28, 2000 at 04:21:19, Andrew Williams wrote:

>On September 27, 2000 at 20:03:27, Peter McKenzie wrote:
>
>>On September 27, 2000 at 17:16:21, Andrew Williams wrote:
>>
>>>On September 27, 2000 at 04:45:38, Eduard Nemeth wrote:
>>>
>>>>[D]8/8/p3R3/1p5p/1P5p/6rp/5K1p/7k w - - 0 1
>>>>
>>>>Shredder 4 and Fritz 6a this don't find !
>>>>
>>>>Eduard
>>>
>>>PostModernist finds this easily enough:
>>>
>>>9=  +M07     2    102865   1. Re1 Rg1 2. Rf1 a5 3. bxa5 b4 4. a6 b3 5. a7 Rxf1
>>>6. Kxf1 b2 7. a8=Q
>>>
>>>ie 2 seconds, 102865 nodes.
>>
>>LambChop didn't find it, it looks like a nullmove problem to me.
>>After 1.Re1+ Rg1 2.Rf1 black just nullmoves, so the zugzwang is not detected.
>>
>>I guess you don't nullmove in Rook endings?
>>
>
>Correct.

I do nullmoves in rook endings but have a special Zugzwang detection if the side
which wants to make the nullmove has only one piece left. The latest version of
Hossa finds it quickly:

 depth   value    time    nodes pv
    1    -5.64    0.00        2 1.e6xa6
   <1>   -5.64    0.00       21 1.e6xa6
    2    -5.67    0.00       46 1.e6xa6 g3g7
   <2>   -5.67    0.01      155 1.e6xa6 g3g7
    3    -5.60    0.01      233 1.e6xa6 g3g2 2.f2f3
   <3>   -5.60    0.01      323 1.e6xa6 g3g2 2.f2f3
    4    -5.70    0.01      531 1.e6xa6 g3g2 2.f2f1 g2g7
   <4>   -5.70    0.02     1026 1.e6xa6 g3g2 2.f2f1 g2g7
    5    -5.32    0.03     1744 1.e6xa6 g3g4 2.a6a1 g4g1 3.a1a2
!   5    -5.06    0.03     1923 1.e6e1 g3g1 2.e1f1 a5 3.b4xa5
!  <5>   -5.06    0.04     2631 1.e6e1 g3g1 2.e1f1 a5 3.b4xa5
    6    -5.15    0.05     2974 1.e6e1 g3g1 2.e1f1 a5 3.b4xa5 b4
   <6>   -5.15    0.06     4158 1.e6e1 g3g1 2.e1f1 a5 3.b4xa5 b4
    7    -4.91    0.07     4667 1.e6e1 g3g1 2.e1f1 a5 3.b4xa5 b4
                                4.a6 b3
   <7>   -4.91    0.08     5922 1.e6e1 g3g1 2.e1f1 a5 3.b4xa5 b4
                                4.a6 b3
!   8    -4.42    0.09     6558 1.e6e1 g3g1 2.e1f1 a5 3.b4xa5 b4
                                4.a6 b3 5.a7
!  <8>   -4.42    0.09     6606 1.e6e1 g3g1 2.e1f1 a5 3.b4xa5 b4
                                4.a6 b3 5.a7
    9    -4.27    0.09     7019 1.e6e1 g3g1 2.e1f1 a5 3.b4xa5 b4
                                4.a6 b3 5.a7 g1xf1 6.f2xf1
   <9>   -4.27    0.09     7067 1.e6e1 g3g1 2.e1f1 a5 3.b4xa5 b4
                                4.a6 b3 5.a7 g1xf1 6.f2xf1
!  10       #7    0.10     8107 1.e6e1 g3g1 2.e1f1 a5 3.b4xa5 b4
                                4.a6 b3 5.a7 g1xf1 6.f2xf1 b2
                                7.a7a8Q
! <10>      #7    0.13    10157 1.e6e1 g3g1 2.e1f1 a5 3.b4xa5 b4
                                4.a6 b3 5.a7 g1xf1 6.f2xf1 b2
                                7.a7a8Q

Greetings,
Steffen.




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