Aart's Computer Checkers Page

Discussions related to checkers can be found at the World Draughts Forum. For more resources and a proof that checkers has been solved see the Chinook project. Ongoing thoughts related to checkers programming can often be found at Aart's blog.

Checkers Engine: BikMove

Aart Bik implemented an 8x8 checkers engine called BikMove that can be plugged into Martin Fierz' excellent CheckerBoard application. To install BikMove v1.2.1, download the following zip file, unzip it in the checkboard engines directory, and then import the engine through the Engine=>Select menu: All C++ source code of BikMove has been written by Aart (except the endgame databases probing code, which is used with kind permission of Martin Fierz).

Perft for Checkers

The perft method originated in the chess programming community as a way to verify the move generator of an engine. The method traverses the game tree up to various, increasing depths to count all leaf nodes at each given depth. These results are compared with pre-computed values to isolate bugs and timings can be used to analyze the performance of the move generator. The perft method can be applied to other game engines as well, such as perft for reversi or, as done on here, perft for checkers. Below, checkers perft numbers from the start position are given using the move generator of BikMove on a 2.2 GHz Core 2 Duo (optimized for speed with bulk counting). Please note that the move generator does not eliminate duplicate captures (viz. the situation where a king can capture the same pieces in different directions; a situation that starts to occur at depth 12 and up). 
perft(1)  =                 7  in         0 ms.
perft(2)  =                49  in         0 ms.
perft(3)  =               302  in         0 ms.
perft(4)  =              1469  in         0 ms.
perft(5)  =              7361  in         0 ms.
perft(6)  =             36768  in         1 ms.     36,768.0 KN/s
perft(7)  =            179740  in         5 ms.     35,948.0 KN/s
perft(8)  =            845931  in        23 ms.     36,779.6 KN/s
perft(9)  =           3963680  in        86 ms.     46,089.3 KN/s
perft(10) =          18391564  in       398 ms.     46,210.0 KN/s
perft(11) =          85242128  in      1821 ms.     46,810.6 KN/s
perft(12) =         388623673  in      8395 ms.     46,292.3 KN/s
perft(13) =        1766623630  in     37182 ms.     47,512.9 KN/s
perft(14) =        7978439499  in    174947 ms.     45,604.9 KN/s
perft(15) =       36263167175  in    808155 ms.     44,871.5 KN/s
perft(16) =      165629569428  in   3767118 ms.     43,967.2 KN/s
perft(17) =      758818810990  in  17317695 ms.     43,817.5 KN/s
perft(18) =     3493881706141
perft(19) =    16114043592799
perft(20) =    74545030871553
perft(21) =   345100524480819
perft(22) =  1602372721738102
perft(23) =  7437536860666213
perft(24) = 34651381875296000
Aart implemented a distributed version to compute perft(18) through perft(24) on a cluster of machines (further optimized with a "hard collision"-free transposition table as well as bulk counting). The perft breakdown per move for these depths, an important debugging feature often referred to as "divide", is shown below. 
move      divide(18)     divide(19)     divide(20)      divide(21)       divide(22)       divide(23)        divide(24)
----------------------------------------------------------------------------------------------------------------------
12-16:  550829166472  2517202147314 11531470109861  52945190026737  243598269855110 1123463594881857  5192042148594780
11-16:  566149929068  2564849953998 11736729175821  53527954221225  246743868125768 1131373985922218  5248615918291379
11-15:  435063007630  2041959240377  9515983205474  44775005468548  209016678583301  984253557821317  4602138522979438
10-15:  472279451484  2180656975018 10055597639275  46574865098865  215412869777867 1000606302770349  4643700995955222
10-14:  402570639569  1859042884028  8600202424158  39822944739732  184865466345796  856779998157523  3988937724259353
 9-14:  441590753001  2068865301476  9698986164172  45530585259776  213736468971938 1003310451936358  4712325943133747
 9-13:  625398758917  2881467090588 13406062152792  61923979665936  288999100078322 1337748969176591  6263620622082081
----------------------------------------------------------------------------------------------------------------------
       3493881706141 16114043592799 74545030871553 345100524480819 1602372721738102 7437536860666213 34651381875296000
Thanks to Murray Cash, Martin Fierz, Ed Gilbert, Rein Halbersma (first to report perft(22)), Jonathan Schaeffer, and Ed Trice for verifying various perft numbers with their own move generators.

Checkers for Android

[Icon] Checkers for Android is a standalone application that consists of a 8x8 checkers engine (a Java version that evolved into the C++ engine BikMove) together with a GUI.
Please note that this page is privately maintained by Aart Bik. LinkedIn