Xiphos

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[ Xiphos and Makhaira [1] Xiphos,

an UCI compliant open source chess engine by Milos Tatarevic, written in C, licensed under the GNU General Public License v3.0, first released on February 28, 2018. Xiphos utilizes bitboards with BERLEF mapping (a1=56, a8=63, h1=0, h8=7) [2]. Sliding piece attacks are determined by either magic bitboards, or if compiled for BMI2 capable x86-64 processors, by PEXT bitboards. Xiphos executables are available to run under Linux, Mac OS and Windows. Still work in progress with a relatively simple evaluation function, the first Xiphos release should already be on par with engines rated around 3000 Elo on CCRL 40/4 scale [3].

Selected Features#

Search

[7]

• Parallel Search using Threads
• Iterative Deepening
• Aspiration Windows
• Principal Variation Search
• Transposition Table

Shared Hash Table

• Move Ordering

Countermove Heuristic History Heuristic Internal Iterative Deepening Killer Heuristic MVV/LVA SEE

• Singular Extensions (0.2)
• Pruning

Futility Pruning Late Move Pruning Null Move Pruning ProbCut

• Reductions

Late Move Reductions Razoring

• Quiescence Search

Evaluation

[8]

• Tapered Eval
• Material

Bishop Pair

• Pawn Structure

Pawn Hash Table Doubled Pawn Isolated Pawn Passed Pawn

• Mobility
• Rooks on (Semi) Open Files
• King Safety

Misc#

• Perft
• Magic Bitboards
• PEXT Bitboards

Forum Posts#

2018#

• New engine: Xiphos by Milos Tatarevic, CCC, February 28, 2018
• Xiphos 0.2 by Milos Tatarevic, CCC, April 14, 2018
• Xiphos 0.2.2 by Milos Tatarevic, CCC, April 20, 2018
• Xiphos 0.3 by Milos Tatarevic, CCC, June 25, 2018
• Xiphos 0.4 by Milos Tatarevic, CCC, September 24, 2018
• The Xiphos Material Evaluator by Dennis Sceviour, CCC, November 05, 2018 » Material

2019#

• xiphos 64 bit random number by Pedro Castro, CCC, February 28, 2019 » Pseudorandom Number Generator
• Xiphos 0.5 by Milos Tatarevic, CCC, March 11, 2019

External Links#

Chess Engine#

• GitHub - milostatarevic/xiphos: UCI chess engine
• Xiphos in CCRL 40/40

Misc#

• Xiphos from Wikipedia
• The SWORD Project from Wikipedia

References#

1. ↑ Graphic of Bronze Age swords, Xiphos (fig. 1-3 left) and Makhaira (fig. 4), Image from the 4th edition of Meyers Konversationslexikon (1885–90), Wikimedia Commons
2. ↑ xiphos/game.h at master · milostatarevic/xiphos · GitHub
3. ↑ New engine: Xiphos by Milos Tatarevic, CCC, February 28, 2018
4. ↑ “Deep Thinking” | Kasparov
5. ↑ Garry Kasparov (2017). Deep Thinking: Where Machine Intelligence Ends and Human Creativity Begins. with contributions by Mig Greengard, amazon.com
6. ↑ xiphos/README.md at master · milostatarevic/xiphos · GitHub
7. ↑ xiphos/search.c at master · milostatarevic/xiphos · GitHub
8. ↑ xiphos/eval.c at master · milostatarevic/xiphos · GitHub

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