This includes personal conversations with programmers, and the exchange of source codes as well as discussions via email. Many a reference used in this thesis is not available in a scientifically elaborate form. This thesis also does not aim at the explicit consideration of known computer-chess architectures, such as Rotated Bitboards or the 0x88 representation. In Preliminary Considerations he mentioned discussions with Chrilly Donninger, Fabien Letouzey and Tord Romstad, and the exchange of source codes :
An essential reason for the success of this 64-bit computer-chess engine was the use of highly sophisticated perfect hash functions and magic multipliers for the computation of compound bit-patterns (bitboards) via perfect hashing.Įvaluation was only marginally covered in Reul's thesis. This engine was able to reach the 3rd place at the 15th World Computer-Chess Championship, Amsterdam (NL) 2007. įritz Reul on an essential reason of Loop's success in Amsterdam in his thesis :Ī complete computer-chess architecture based on hash functions and magic multiplications for the examination of bitboards is implemented in the computerchess engine Loop Amsterdam. Further, iterative alpha-beta bounded static exchange evaluation was applied to Loop Amsterdam, also performing a parallel search for a quad-core processor, which played a strong WCCC 2007 in Amsterdam, and became Third, behind the later disqualified Rybka, and Zappa. The bitboard based Loop applies Magic Bitboards for sliding piece attack generation. The high performance was just as important for these projects as the simplicity and ease of implementation in the following two environments: (1) the environment of a sophisticated computer-chess machine (Hydra) and (2) the environment of a commercial games console with the highest quality and security standards. The computerchess architecture was later implemented partially in Hydra and completely in Wii Chess by Nintendo (see Section 2.1). This computerchess architecture was first implemented in the quite successful computerchess engine Loop Leiden 2006. The non-bitboard data-structure of Loop was also applied in Chrilly Donninger's chess machine Hydra.
A specially adapted version called Loop Express became the engine of Wii Chess for the Nintendo Wii console in 2008. It participated as Loop Leiden at the DOCCC 2006, becoming strong runner up behind Rybka. The 32-bit program, based on Reul's former program List, relies on a 15x12 board representation in conjunction with disjoint piece-lists with adequate move generation of blocker loops.
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