I was looking for some more difficult checkers positions to test my checker program milhouse against. Jim Loy’s excellent page has a list of difficult ones. Unlike the typical puzzles I have in my Encylopedia of Checkers Puzzles by Pike, these aren’t the kind of puzzles you typically find in 10 ply. In particular, his puzzle #2 was marked as “difficult”, and was a “cook” of a position thought to be a draw. Interestingly enough, my checkers program, as feeble as its evaluation function is, seems to find the winning line for Red with a 15 ply search.

Loy’s Checkers Problems

Puzzle Jim Loy, Puzzle #2 loaded.
Color is set to red.
	   White  
	+--------+
	| - w - -|
	|w - - w |
	| w r - w|
	|w w - w |
	| w r - w|
	|r - r - |
	| - r - r|
	|- r r r |
	+--------+
	   Red    

milhouse: depth 15
search depth is now 15
milhouse: annotate
	1-6 : -359
	2-6 : -61
	3-8 : -425
	5-9 : -111
	7-11 : -180
	10-14 : -239
	15-18 : -119
	23-26 : 124
	23-27 : -40
milhouse: playout
     1. 23-26 [  124] 31x22 [ -119]
     2.   2-6 [  182] 16-11 [ -181]
     3.  7x23 [  188] 24-19 [ -187]
     4. 15x24 [  238] 28x19 [ -237]
     5. 10-14 [  239] 17x10 [ -239]
     6.  6x24 [  242] 22-18 [ -241]
     7. 24-27 [  244]  13-9 [ -235]
     8.  5x14 [  261]  18x9 [ -233]
     9. 27-31 [  237] 25-22 [ -202]
    10. 31-26 [  251] 22-18 [ -251]
	   White  
	+--------+
	| - - - -|
	|- - R - |
	| - r - w|
	|w - w - |
	| - - - -|
	|r - - w |
	| - - - -|
	|- r - r |
	+--------+
	   Red    

milhouse: playout
     1. 26-22 [  251] 18-15 [ -249]
     2. 23-27 [  271] 15-11 [ -312]
     3. 22-18 [  313] 21-17 [ -264]
     4. 18-15 [  267]  11-8 [ -267]
     5. 27-31 [  312]   8-4 [ -269]
     6. 15-11 [  335] 17-13 [ -341]
     7. 31-27 [  342]   9-6 [ -342]
     8.  1x10 [  346]  13-9 [ -346]
     9. 12-16 [  346]   9-6 [ -346]
    10. 27-24 [  352]   6-1 [ -352]
	   White  
	+--------+
	| - - - -|
	|- - - - |
	| R - - -|
	|w - - - |
	| r - - -|
	|- R r - |
	| - - - -|
	|W r - W |
	+--------+
	   Red    

milhouse: playout
     1. 16-19 [  352]   1-5 [ -354]
     2. 19-23 [  377]   5-1 [ -375]
     3. 23-26 [  393]   1-5 [ -400]
     4. 26-30 [  401]   5-9 [ -450]
     5. 24-19 [  401]   9-5 [ -451]
     6. 30-25 [  521]   5-1 [ -656]
     7. 10-14 [  656] 20-16 [-9986]
     8. 11x20 [ 9987]   4-8 [-9988]
     9.  3x12 [ 9989]   1-6 [-9990]
    10. 19-15 [ 9991]   6-9 [-9992]
	   White  
	+--------+
	| - - - -|
	|- - - R |
	| - - - -|
	|R - - - |
	| - R r -|
	|r - - W |
	| - - - -|
	|- - - - |
	+--------+
	   Red    

milhouse: playout
     1. 15-10 [ 9993]  9x18 [-9994]
     2. 20-24 [ 9995] 18-23 [-9996]
     3. 24-19 [ 9997] 23x16 [-9998]
     4. 12x19 [ 9999]	   White  
	+--------+
	| - - - -|
	|- - - R |
	| - - - -|
	|- r - - |
	| - - - -|
	|- - R - |
	| - - - -|
	|- - - - |
	+--------+
	   Red    

milhouse: