FrankWalter

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FrankWalter, (Frank Walter, Frank-Walter) a Chess Engine Communication Protocol compliant open source chess engine by Laurens Winkelhagen, written in Java, licensed under the GPL v3.0. After continuing the development on his old engine, Laurens Winkelhagen published FrankWalter 2.2.0 in November 2018 , short before it had its over the board debut at the PT 54 in Leiden.

=Features=

Board Representation
FrankWalter represents the board using a two-dimensional array of piece bitboards, indexed by color and type, and further has an 8x8 board for a square-centric view. These are all members of a board class along with the usual stuff specifying a chess position, such as side to move, castling rights, en passant target, halfmove clock, and an array of Zobrist keys to detect repetitions along the actual game record and variation. Despite sliding piece attacks are determined by a memory friendly approach of Kindergarten bitboards for files and Magic bitboards for ranks and bishops, FrankWalter keeps attack tables in classical Chess 4.5 style, that is two bitboard arrays (ATKFR and ATKTO) indexed by square, While along with keeping bitboards for pinned pieces, this seems an reasonable approach to implement legal move generation, the culprit is the incremental update, in particular using a copy-make stack to copy the 1K attack table not only during make but also back during unmake.

Search

 * Lazy SMP
 * Fractional Ply Iterative Deepening
 * Principal Variation Search
 * Aspiration Windows
 * Transposition Table
 * Selectivity
 * Null Move Pruning
 * Late Move Reductions
 * Check Extensions
 * Quiescence Search
 * Move Ordering
 * PV-Move
 * Killer Heuristic
 * History Heuristic
 * Static Exchange Evaluation

Evaluation

 * Material
 * Piece-Square Tables
 * Mobility
 * Pawn Structure
 * King Safety
 * Tapered Eval
 * Texel's Tuning Method

Misc

 * Syzygy Bases via JNI Fathom Bridge (JSyzygy)
 * Beowulf Opening Book Format

=Forum Posts=
 * Revived Engine - Frank Walter 2.2.0 (Java - WB) by Laurens Winkelhagen, CCC, November 20, 2018
 * Frank Walter by Gabor Szots, CCC, November 26, 2018
 * Frank-Walter & Tablebases by Ted Summers, CCC, September 27, 2019

=External Links=

Chess Engine

 * GitHub - ljgw/frankwalter: a WB2 java chess engine
 * FrankWalter in CCRL 40/40

Misc

 * Frank (given name) from Wikipedia
 * Walter (name) from Wikipedia
 * Frank Walter from Wikipedia
 * Frank Walter (Antiguan Artist)

=References= Up one level