Contributions to https://chessprogramming.wikispaces.com/ are licensed under a Creative Commons Attribution Share-Alike 3.0 License. 
Portions not contributed by visitors are Copyright 2018 Tangient LLC
TES: The largest network of teachers in the world
Portions not contributed by visitors are Copyright 2018 Tangient LLC
TES: The largest network of teachers in the world
Table of Contents
Ronald de Man, alias Syzygy,
a Dutch mathematician, computer scientist and IP lawyer, in the 90s researcher at Eindhoven University of Technology, competitor at the International Mathematical Olympiad 1990, winning the Silver medal [1] , and the ACM International Collegiate Programming Contest 1995, to win Bronze within the ARoMA team from Delft University of Technology [2] [3] . He is co-developer of the Linux desktop environment and graphical user interface GNOME [4] , and as chess programmer author of the chess and Antichess [5] playing program Sjaak, which plays at FICS under the handle TrojanKnight [6] [7] [8]. He further ported Stockfish to plain C, dubbed CFish.
Scoring Root Moves
Ronald de Man proposed a method to apply randomness [9] and/or bonuses, i.e. developing bonus, or penalties suggested by an oracle, in scoring moves at the root without any changes in alpha-beta search or leaf evaluation, and without any problems with the transposition table [10]:- If v <= alpha, then x <= alpha,
- If v >= beta, then x >= beta,
- If alpha < v < beta, then x = v.
If you search a move, you want to know if its real value + bonus[n] is bigger than alpha. So you want to know if its real value is bigger than alpha-bonus[n]. So you give Search() the bounds alpha-bonus[n] and beta-bonus[n], and add bonus[n] to the result. And you do this in SearchRoot().So no fudging with hash table scores whatsoever!
Of course this trick gives all kinds of possibilities. Not only can you stimulate development, or add in some randomization. It is also easy to solve the 'underpromotion' problem: to prevent the program from under-promoting to a rook (in situations where the piece will probably be captured the next move anyway), you give underpromotion moves a penalty. Or in trivially drawn endgames like KRKR you give captures a bonus. Or in not-so-trivially drawn endgames for which tablebases give draw values you give moves that give away a piece (but do not change the outcome) a penalty, hoping that the opponent will make a fatal mistake further on in the game :-)
Ronald de Man
Bloom Filter
Ronald de Man revealed the trick to speed up repetition detection with a Bloom filter, implemented as a small hash table indexed by some lower bits of the hash-key, to increment a counter while entering and decrement the counter while leaving a node [11] [12] .Syzygy Bases
In April 2013, Ronald de Man published his Syzygy Bases [13] , a compact endgame tablebase of up to six pieces. It consist of two sets of files, WDL files storing win/draw/loss information considering the fifty-move rule, for access during search, and DTZ files with distance-to-zero information for access at the root [14] [15] .Selected Publications
[16]Forum Posts
External Links
Syzygy (mathematics) from Wikipedia
References
What links here?
Up one level