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Subject: Handling of KNN-kp positions.

Author: Bernhard Bauer

Date: 03:58:59 02/10/98


Hallo everybody,

As its said Bruce Moreland is using an EGTB for the 5-man ending KNNKP.
This is a simple and in some sense a brutal method of takling such a
problem
which uses in addition a lot of disk space.

IMHO the method of Bob Hyatt is much smarter and needs no disk space at
all.
This method works of course not so well if crafty has the KNN side.
Crafty
will in some very rare cases not be able to win,if its possible,
however, if Crafty has the weaker part Crafty will draw even in hopeless
situations. This is achieved by a new extremly tricky method.

But look yourself.
In the following position I (white) had good hope to win.
--> FEN: k1K/8/2N/2N/8/8/1p/8 w
The only difficulty IMNSHO was whether to move Na6 or Ne6. Since Ne6
centralizes the knight more than the weak edge position after Na6 I
moved
Ne6 hoping to win this game.
However I completely overlooked the tricky answer of Crafty.
Crafty played the great move b1=B !!!!!
Now it became obvious that white could'nt win. Because the endgame
KNNKB is a general draw, isn't it?

The output given by Crafty follows somewhat modified.
BTW you may need a grain of salt -))


Kind regards
Bernhard

-----------------------------------------------------------------

Crafty v14.9

White(1): ponder off
pondering disabled.
White(1): book   off
book file disabled.
White(1): noise    0
noise level set to 0.
White(1): hash    3M
hash table memory = 3M bytes.
White(1): hashp 640K
pawn hash table memory = 640K bytes.
White(1): time   cpu
using cpu time
White(1): st      60
search time set to 60.00.
White(1): setboard k1K/8/2N/2N/8/8/1p/8 w

       +---+---+---+---+---+---+---+---+
    8  | *K|   | K |   |   |   |   |   |
       +---+---+---+---+---+---+---+---+
    7  |   |   |   |   |   |   |   |   |
       +---+---+---+---+---+---+---+---+
    6  |   |   | N |   |   |   |   |   |
       +---+---+---+---+---+---+---+---+
    5  |   |   | N |   |   |   |   |   |
       +---+---+---+---+---+---+---+---+
    4  |   |   |   |   |   |   |   |   |
       +---+---+---+---+---+---+---+---+
    3  |   |   |   |   |   |   |   |   |
       +---+---+---+---+---+---+---+---+
    2  |   | *P|   |   |   |   |   |   |
       +---+---+---+---+---+---+---+---+
    1  |   |   |   |   |   |   |   |   |
       +---+---+---+---+---+---+---+---+
         a   b   c   d   e   f   g   h

White(1): d
White(1): search Ne6
White(1): move
end-game phase
              clearing hash tables
              time surplus   0.00  time limit 1:00 (1:00)
              depth   time  score   variation (1)
                1     0.00  -4.01   1. Ne6 b1=Q
                1->   0.00  -4.01   1. Ne6 b1=Q
                2     0.01     ++   1. Ne6!!
                2     0.01   0.00   1. Ne6 b1=B
                2->   0.02   0.00   1. Ne6 b1=B
                3     0.02   0.00   1. Ne6 b1=B
                3->   0.03   0.00   1. Ne6 b1=B
                4     0.03   0.00   1. Ne6 b1=B
                4->   0.03   0.00   1. Ne6 b1=B
                5     0.04   0.00   1. Ne6 b1=B
                5->   0.04   0.00   1. Ne6 b1=B
               10->   0.07   0.00   1. Ne6 b1=B
               30->   0.19   0.00   1. Ne6 b1=B
               35->   0.22   0.00   1. Ne6 b1=B
               40->   0.24   0.00   1. Ne6 b1=B
               45->   0.26   0.00   1. Ne6 b1=B
               50->   0.28   0.00   1. Ne6 b1=B
               55->   0.31   0.00   1. Ne6 b1=B
               60->   0.33   0.00   1. Ne6 b1=B
              time:  0.35  cpu:9%  mat:6  n:588  nps:10000
              ext-> checks:134 recaps:0 pawns:240 1rep:3
              predicted:0  nodes:588  evals:8
              endgame tablebase-> probes done: 0  successful: 0
              hashing-> trans/ref:102%  pawn:50%  used:w0% b0%

White(1): Ne6
              time used:   0.35

execution complete.
---------------------------------------------------------------------




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