Ethereal, an UCI compliant open source chess engine written by Andrew Grant in C, licensed under the GNU GPL and first officially released in June 2016 [1]. Ethereal is greatly influenced from Crafty, Stockfish, TSCP, MadChess, and Fruit [2].
Ethereal night sky [3]

Features

Board Representation

• Bitboards
• Fancy Magic Bitboards
• 8x8 Board

Search

• Lazy SMP since 8.60 SMP ^[5]
• Iterative Deepening
• Aspiration Windows
• PVS Alpha-Beta
• Transposition Table
• Selectivity
  • Check Extensions
  • Delta Pruning
  • Futility Pruning
  • Late Move Reductions
  • Null Move Pruning
  • Razoring
  • Reverse Futility Pruning (Static Null Move Pruning)
• Move Ordering
  • Internal Iterative Deepening
  • MVV/LVA
  • Killer Heuristic
  • History Heuristic
  • Piece-Square Tables

Evaluation

• Tapered Eval
• Material
• Piece-Square Tables
• Mobility
• Outposts
• Rook on (Half) Open File
• Rook on 7th Rank
• Castling Ability
• Pawn Hash Table
• Pawn Structure

See also

• Astronomy

Forum Posts

2016

• Re: How to speed up my engine by Günther Simon, CCC, May 03, 2016
  Re: How to speed up my engine by Andrew Grant, CCC, May 03, 2016
• Ethereal Bitboard 6.26 Chess Engine...a star is born! by AA Ross, CCC, May 14, 2016
• Ethereal - Official Release by Andrew Grant, CCC, June 25, 2016
• Ethereal - Official Release by Andrew Grant, CCRL Discussion Board, June 25, 2016
• Release of Ethereal7.78 by Andrew Grant, CCC, September 04, 2016

2017

• Official release of Ethereal8.16 by Andrew Grant, CCC, June 03, 2017
• Ethereal8.28 Release by Andrew Grant, CCC, September 13, 2017
• Ethereal8.37 Release by Andrew Grant, CCC, November 10, 2017
• Release of Ethereal 8.60 SMP by Andrew Grant, CCC, December 10, 2017
• Ethereal 8.61 -- Small bugfix to 8.60 by Andrew Grant, CCC, December 12, 2017
• Time Managment translating to SMP by Andrew Grant, CCC, December 23, 2017 » Parallel Search, Time Management

2018

• Official Release of Ethereal9.00 by Andrew Grant, CCC, February 15, 2018
• Official Release of Ethereal9.30 by Andrew Grant, CCC, March 20, 2018

External Links

Chess Engine

• GitHub - AndyGrant/Ethereal: Ethereal UCI Chess Engine
• Ethereal in CCRL 40/4

Misc

• ethereal - Wiktionary
• Ethereal from Wikipedia
• Ether from Wikipedia
• Ethereal wave from Wikipedia
• Ethereal cardinal from Wikipedia
• The Ethereal from Truth is Beauty, July 07, 2015
• Jean luc Ponty - Ethereal Mood (1978), YouTube Video
  

References

1. ^ Ethereal - Official Release by Andrew Grant, CCRL Discussion Board, June 25, 2016
2. ^ Ethereal/README.md at master · AndyGrant/Ethereal · GitHub
3. ^ A total eclipse of the Moon is an impressive spectacle. But it also provides another viewing opportunity: a dark, moonlight-free starry sky. At Cerro Paranal in the Chilean Atacama Desert, one of the most remote places in the world, the distance from sources of light pollution makes the night sky all the more remarkable during a total lunar eclipse. This panoramic photo, taken by ESO Photo Ambassador Yuri Beletsky, shows the view of the starry sky from the site of ESO’s Very Large Telescope (VLT) at Cerro Paranal during the total lunar eclipse of December 21, 2010. The reddish disc of the Moon is seen on the right of the image, while the Milky Way arches across the heavens in all its beauty. Another faint glow of light is also visible, surrounding the brilliant planet Venus in the bottom left corner of the picture. This phenomenon, known as zodiacal light, is produced by sunlight reflecting off dust in the plane of the planets. It is so faint that it’s normally obscured by moonlight or light pollution. Image by ESO, Yuri Beletsky, CC BY 4.0, Wikimedia Commons, Beauty from Wikipedia
4. ^ Features based on GitHub - AndyGrant/Ethereal: Ethereal UCI Chess Engine
5. ^ Ethereal's 8.60 Lazy SMP inspired by Demolito by Lucas Braesch, see Release of Ethereal 8.60 SMP by Andrew Grant, CCC, December 10, 2017

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