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Article #5184

Checkmate eval problem

#5184
From: Dr Michael J. White
Date: Sun, 10 Apr 1994 23:36
109 lines
4775 bytes
Hello!

This position shows that counting behavior I mentioned in an earlier
post.  It's not the same position that I mentioned, but this one is weird
enough.  The fix from Kong Sian gets rid of the funny evaluation sequence.

Now, no mating lines show at all in the evals (I don't know if that
fact is bad or good).  The same final move is chosen in both cases.
A small detail is that I had HISTORY off in the first run, but HISTORY
was on in the second...

The fix from Kong was in search.c:

Change this line:
     if (flag.hash /* && ply <= Sdepth */ && *rpt==0 ...etc...
to:
     if (flag.hash    && SAVEHT           && *rpt==0 ...etc...

Here's the position, before and after output.

Have fun,
Mike



THE POSITION:
----------------------------------------
1 1 post book force
e2e4 g8f6 e4e5 f6d5 d2d4 d7d6 f1c4 d5b6 c4b3 c8f5 d1f3 d8c8 g1e2 e7e6 b1c3
d6e5 d4e5 b8d7 e2d4 f5g6 h2h4 c7c5 h4h5 c5d4 h5g6 f7g6 c3b5 f8b4 e1d1 d7e5
f3e2 c8c5 c1f4 b6c4
depth 6 bd go quit

 R - - - K - - R
 P P - - - - P P
 - - - - P - P -
 - n Q - N - - -
 - B N P - b - -
 - b - - - - - -
 p p p - q p p -
 r - - k - - - r


BEFORE IMPLEMENTING "&& SAVEHT" :
------------------------------------------------------------
Move# 18    Target= 0    Clock: 1019845
 2.   -108    0     2131   f4e5  c4e5  h1h7 
 3&    -69    1    12622   f4e5  c4e5  b3e6  a7a6  a2a4 
 3+    -11    2    17078   b3c4  c5c4  e2c4  e5g4  c4b4  g4f2  d1c1 
 3&    255    3    25114   b3c4  c5c4  f4e5  c4e2 
 3.    255    4    30676   b3c4  c5c4  f4e5  c4e2 
 4&    297    8    54214   b3c4  c5c4  f4e5  d4d3  e2d3  a8d8  b5d4  c4d3 
                           c2d3 
 4.    297   12    78587   b3c4  c5c4  f4e5  d4d3  e2d3  a8d8  b5d4  c4d3 
                           c2d3 
 5&    298   17   113527   b3c4  c5c4  f4e5  d4d3 
 5.    298   19   125766   b3c4  c5c4  f4e5  d4d3 
 6-    157  403  3007551   b3c4  e5c4  e2e3 
 6-    157  415  3098430   f4e5  c4e5  b5a3 
 6-    161  419  3120227   b5d4 
 6-    162  425  3158645   h1h4 
 6-    162  556  4138759   e2e3 
 6&  -9979 1667 12327536   e2e3  c4e3  d1c1  c5c2  b3c2 
 6&  -9975 1925 14026014   h1h4  c4b2  d1c1 
 6&  -9971 2046 15137962   b5d4  c4b2  d1c1 
 6&  -9967 2371 17312422   f4e5  c4b2  d1c1 
 6&    169 2411 17576384   b3c4  h8g8 
 6.    169 2436 17741788   b3c4  h8g8 
1. ... b3c4
Gen 64221213 Node 17741788 Tree 1056 Eval 756197 Rate 7283 EC 634078/121032 RS hi 1 lo 2 
Hin/Hout/Tcol/Coll/Fin/Fout = 2204454/184832/391/0/0/0
My move is: b3c4


AFTER IMPLEMENTING "&& SAVEHT":
------------------------------------------------------------------------
Your move is? 
Move# 18    Target= 0    Clock: 101847
 2.   -108    0     2095   f4e5  c4e5  h1h7 
 3&    -69    1    12980   f4e5  c4e5  b3e6  a7a6  e2c4 
 3+     -6    2    16598   b3c4  e5d7  h1h7  h8h7  c4e6 
 3&    310    4    28994   b3c4  c5c4  f4e5  c4e2  d1e2  d4d3  e2d3  e8g8 
 3.    310    5    35634   b3c4  c5c4  f4e5  c4e2  d1e2  d4d3  e2d3  e8g8 
 4&    313    7    52090   b3c4  c5c4  f4e5  d4d3  e2d3  c4g4  d3f3  g4f3 
                           g2f3 
 4.    313   11    75691   b3c4  c5c4  f4e5  d4d3  e2d3  c4g4  d3f3  g4f3 
                           g2f3 
 5&    314   16   104920   b3c4  c5c4  f4e5  d4d3 
 5.    314   17   116116   b3c4  c5c4  f4e5  d4d3 
 6-    171  186  1362647   b3c4  e5c4  e2e3 
 6-    171  198  1446589   f4e5  c4e5  e2e3 
 6-    174  202  1465677   b5d4 
 6-    175  206  1490860   b5a7 
 6-    176  207  1500850   h1h4 
 6-    176  224  1608229   e2e3 
 6&  -1538 22395 17793175   e2e3  d4e3  a2a4  e3f2  d1e2  c4a3  b2a3  f2f1 
                           a1f1  c5b5  a4b5 
 6&   -412 23174 23041665   h1h4  c5b5  d1c1  b5c5  e2e4  e8c8  f4e5  c4e5 
                           b3e6  c8b8 
 6&    -35 23562 25577787   f4e5  d4d3  c2d3  c4e5  d3d4  a8d8  b3e6  e8f8 
 6&    183 23581 25701602   b3c4  c5b6 
 6.    183 23622 25964357   b3c4  c5b6 
1. ... b3c4
Gen 92572985 Node 25964357 Tree 1041 Eval 1272710 Rate 1099 EC 1003330/268330 RS hi 1 lo 2 
Hin/Hout/Tcol/Coll/Fin/Fout = 3423531/327298/2347/0/0/0
My move is: b3c4
------------------------------------
THE END
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From: mwhite@osiris.cso.uiuc.edu (Dr Michael J. White)
Newsgroups: gnu.chess
Subject: Checkmate eval problem
Date: 10 Apr 1994 23:36:42 GMT
Organization: University of Illinois at Urbana
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