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Subject: Re: Completely blocked positions, some interesting things

Author: Jeremiah Penery

Date: 13:35:28 10/04/02

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On October 04, 2002 at 08:03:19, Omid David wrote:

>And a third position which is also a draw:
>
>[D] 8/8/8/k3p3/1p1pPp2/1PpP1P2/B1P5/1K6 w - - 0 1

No fair, an illegal position! :)

The algorithm doesn't do very well here.  It sees there is a potential path for
the king, and doesn't give a drawscore.  I think it's sort of failing at the
right edge of the board in certain circumstances.

I figured out the problem, and now it does well here:

With:

                1     0.00   0.00   1. Kc1
                1->   0.00   0.00   1. Kc1
               ..........................................
               45     4.33   0.00   1. Kc1 Kb5 2. Bb1 Kc5 3. Kd1 Kd6 4.
                                    Ke2 Ke6 5. Kf2 Kf6 6. Kg2 Kg5 7. Kh3
                                    Kh5 8. Ba2 Kg5 9. Bb1
               45->   4.33   0.00   1. Kc1 Kb5 2. Bb1 Kc5 3. Kd1 Kd6 4.
                                    Ke2 Ke6 5. Kf2 Kf6 6. Kg2 Kg5 7. Kh3
                                    Kh5 8. Ba2 Kg5 9. Bb1

  Elapsed Time: 4.42, CPU Time: 4.24, CPU Use: 95%
  Material Balance: 350, Previous Moves Predicted: 0
  Nodes: 3952436, Evaluations: 1585606, FH%: 89%, NPS: 894k
  EXTENSIONS->
   Threat: 11, Passed Pawn: 10565, Recapture: 6796
   One-Reply: 3021, Check: 382285
  PRUNING-> Razors-> White: 2464, Black: 19345
            Futility-> White: 83766, Black: 247508
  TABLEBASES-> Probes: 53, Successful: 18
  HASH TABLES-> Hash Hits: 59% (816165/1365799)
                Pawn Hash Hits: 99% (2287204/2288627)
                Hash Table Filled: 24%


Without:

                1     0.00   3.40   1. Kc1
                1->   0.00   3.40   1. Kc1
               ...........................
               41     4.43     --   1. Kc1
               41     6.72   0.00   1. Kc1 Kb6 2. Kd1 Kc6 3. Ke2 Kd6 4.
                                    Kf2 Ke6 5. Kg2 Kf6 6. Kf1 Kg6 7. Kg2
                                    Kh6 8. Kh3 Kg5 9. Kh2 Kg6 10. Kh3 Kg5
               41->   6.72   0.00   1. Kc1 Kb6 2. Kd1 Kc6 3. Ke2 Kd6 4.
                                    Kf2 Ke6 5. Kg2 Kf6 6. Kf1 Kg6 7. Kg2
                                    Kh6 8. Kh3 Kg5 9. Kh2 Kg6 10. Kh3 Kg5
               ...........................
               45    28.70   0.00   1. Kc1 Kb6 2. Kd1 Kc6 3. Ke2 Kd6 4.
                                    Kf2 Ke6 5. Kg2 Kf6 6. Kf1 Kg6 7. Kg2
                                    Kh6 8. Kh3 Kg5 9. Kh2 Kg6 10. Kh3 Kg5
               45->  28.70   0.00   1. Kc1 Kb6 2. Kd1 Kc6 3. Ke2 Kd6 4.
                                    Kf2 Ke6 5. Kg2 Kf6 6. Kf1 Kg6 7. Kg2
                                    Kh6 8. Kh3 Kg5 9. Kh2 Kg6 10. Kh3 Kg5

  Elapsed Time: 28.78, CPU Time: 28.04, CPU Use: 97%
  Material Balance: 350, Previous Moves Predicted: 0
  Nodes: 32458587, Evaluations: 5693896, FH%: 97%, NPS: 1127k
  EXTENSIONS->
   Threat: 835, Passed Pawn: 500170, Recapture: 8659
   One-Reply: 70371, Check: 1464672
  PRUNING-> Razors-> White: 298398, Black: 84185
            Futility-> White: 4197130, Black: 1149765
  TABLEBASES-> Probes: 6265, Successful: 1612
  HASH TABLES-> Hash Hits: 103% (15629675/15116155)
                Pawn Hash Hits: 99% (13413939/13418667)
                Hash Table Filled: 86%



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