chess22k

toc
 * Home * Engines * chess22k**

an UCI compliant open source chess engine by Sander Maassen vd Brink, written in Java first released in January 2017. While already in the 2400 Elo range using a 64-bit [|Java Runtime Environment (JRE)], it has not initially implemented a tapered evaluation, but abrupt transition based on piece counts per side to distinguish between middlegame and endgame terms. However, tapered evaluation was implemented in chess22k **1.5** along with new evaluation terms adjusted by Texel's tuning method. In November 2017, chess22k had its over the board tournament debut, version **1.6** played the CSVN PT 52 in Leiden, quite successful - shared 4th place with 6/9. Soon released afterwards, chess22k **1.6** requires Java 9.
 * chess22k**,

=Features=

Board Representation

 * Bitboards
 * Magic Bitboards

Search

 * Iterative Deepening
 * Aspiration Windows
 * Principal Variation Search
 * Transposition Table
 * Move Ordering
 * History Heuristic
 * Internal Iterative Deepening
 * Killer Heuristic
 * Selectivity
 * Null Move Pruning
 * Late Move Reductions
 * SEE Pruning

Evaluation

 * Evaluation Hash Table
 * Tapered Eval 1.5
 * Material
 * Bishop Pair
 * Piece-Square Tables
 * Mobility
 * Trapped Pieces
 * Rooks on (Semi) Open Files
 * Outposts
 * Pawn Hash Table
 * Pawn Structure
 * Doubled Pawn
 * Isolated Pawn
 * Passed Pawn
 * King Safety
 * Pawn Shelter
 * Tactical Penalties
 * In Check
 * Hanging Pieces
 * Pinnned Pieces
 * Texel's Tuning Method

=Forum Posts=

2017

 * [|chess22k v1.0] by sandermvdb, OpenChess Forum, January 13, 2017
 * [|New release: chess22k v1.1] by Sander Maassen vd Brink, CCC, February 09, 2017
 * [|chess22k 1.2 released] by Sander Maassen vd Brink, CCC, March 19, 2017
 * [|chess22k 1.3 released] by Sander Maassen vd Brink, CCC, April 26, 2017
 * [|Texel tuning method question] by Sander Maassen vd Brink, CCC, June 05, 2017 » Texel's Tuning Method
 * [|Impressive Texel-tuning results] by Sander Maassen vd Brink, CCC, June 16, 2017
 * [|chess22k 1.4 released] by Sander Maassen vd Brink, CCC, June 18, 2017
 * [|chess22k 1.5 released] by Sander Maassen vd Brink, CCC, August 12, 2017
 * [|chess22k 1.6 released] by Sander Maassen vd Brink, CCC, November 13, 2017
 * [|chess22k 1.7 released] by Sander Maassen vd Brink, December 28, 2017

2018

 * [|chess22k progress overview] by Sander Maassen vd Brink, January 09, 2018
 * [|chess22k 1.8 released] by Sander Maassen vd Brink, CCC, March 04, 2018
 * [|chess22k 1.9 released] by Sander Maassen vd Brink, CCC, April 23, 2018

=External Links=
 * [|GitHub - sandermvdb/chess22k]
 * [|chess22k 1.4 64-bit] in CCRL 40/4

=References= =What links here?= include page="chess22k" component="backlinks" limit="40"
 * Up one Level**