BBChess (SI)

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a free open source engine licensed under the GNU General Public License, written in ANSI C by Borko Bošković starting in 2005. BBChess is Chess Engine Communication Protocol compatible and can be compiled for Linux and Windows. It performs a parallel search using threads, PVS, and determines sliding piece attacks with magic bitboards.

Differential Evolution

BBChess' was further object of research in genetic programming at Computer Architecture and Languages Laboratory [1], Institute of Computer Science at University of Maribor, its evaluation was tuned by differential evolution (DE), which was also topic of Bošković's Ph.D. thesis [2] [3]:

The DE algorithm employs mutation and cross-over operations to generate new individuals and selection operation to select individuals that will survive into next generation. Before selection operation is employed, individuals have to be evaluated. In our case individuals are evaluated according to the games they have played. Therefore individuals play a specific number of games in each generation and individuals with greater efficiency survive into the next generation... 
With the proposed tuning approach, we tuned the chess evaluation function of BBChess chess program. Tuning was done with and without expert knowledge. When we tuned the parameters without expert knowledge, because the search space was huge, we tuned only a few parameters. After 500 generations of the evolutionary process, the value of parameters convergence to the values that relationship were approximately equal as known from the chess theory. When we tuned the parameter values with expert knowledge, the tuning intervals of parameter values were set around the approximate values and the number of tuned parameters was 190. The obtained results show that, our approach was successful. 


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Jean-Paul Bourelly, Darryl Jones, Will Calhoun


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