Pepito
Pepito,
a Chess Engine Communication Protocol and UCI compliant open source chess engine written by Carlos del Cacho in C, first released in September 2000 [1]. The recent version comes with an own GUI written in C++ using wxWidgets and can create opening book databases from a pile of thousands of chess games, applying advanced data structures such as B-trees and skip lists [2]. As bitboard engine, Pepito applies rotated bitboards with 1/2 MiB lookup tables, indexed by the full 8-bit line occupancy, to determine sliding piece attacks. Pepito played the CCT4, CCT5 and CCT6 tournaments.
Screenshot
Features
- NegaScout search algorithm
- Extensions to avoid horizon effect (i.e. check, recapture, pawn push, ...)
- Transposition tables, pawn hash tables and evaluation cache
- AEL-pruning à la Heinz
- Static exchange evaluator, used for move ordering and also to cull losing captures in the quiescence search
- Lazy evaluation
- Nalimov Tablebases
- Pondering
- Book learning
Acknowledgments
Pepito wouldn't have come to life without the help from these guys, acknowledged by Carlos del Cacho in thanx.txt, shipped with the source files [4]:
- Bob Hyatt (Crafty)
- Dušan Dobeš (Phalanx)
- Daniel Homan (EXchess)
- Adrien Regimbald (Faile)
- Jon Dart (Arasan)
- Andrew Tridgell & Jonathan Baxter (KnightCap)
- Stuart Cracraft & Chua Kong Sian (GNU Chess 5)
- John Stanback (GNU Chess 4)
... further ...
- Eugene Nalimov for his Endgame Tablebases
... and
for their papers, and
and many others at CCC for their help...
Selected Games
CCT4, round 2, Pepito - Yace [5]
[Event "CCT4"] [Site "Internet Chess Club"] [Date "2002.01.19"] [Round "2"] [White "Pepito"] [Black "Yace"] [Result "1/2-1/2"] 1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 a6 6.Be3 e6 7.f3 b5 8.g4 h6 9.Qd2 Nbd7 10.O-O-O Bb7 11.h4 b4 12.Na4 Qa5 13.b3 Nc5 14.a3 Rc8 15.Qxb4 Qc7 16.Nxc5 dxc5 17.Qa4+ Nd7 18.Ne2 c4 19.b4 Bc6 20.Qxa6 Ra8 21.Qxc4 Rxa3 22.Bf4 Qb7 23.c3 Bb5 24.Qd4 Ra2 25.Kb1 Rxe2 26.Rh3 e5 27.Bxe5 Bc5 28.Qd5 Bc6 29.Qc4 Bb5 30.Qd5 Bc6 31.Qc4 Bb5 32.Qd5 1/2-1/2
Clones
The program Siboney by Francisco Rivera published in 2002 was based on Pepito with a changed evaluation [6] [7] [8]. In 2003, Deep<9> by pretended author Denis Grafen was proven a blatant clone of Pepito [9] [10] [11].
Forum Posts
2000
- New winboard engine released! by Carlos del Cacho, CCC, September 18, 2000
- Pepito 1.01 uploaded! Bugfix + adjustable hash size by Carlos del Cacho, CCC, September 20, 2000
- About Pepito and Amyan by José Carlos, CCC, September 24, 2000 » Amyan
- Pepito 1.03 available (Move now support & José C. bug fixed) by Carlos del Cacho, CCC, September 25, 2000
- Pepito v1.10 available w source by Carlos del Cacho, CCC, December 22, 2000
2001
- Pepito 1.40 MMX LCT2 test by Gabor Szots, Winboard Forum, October 02, 2001 » LCT II
- Pepito 1.42 MMX build by Dann Corbit, Winboard Forum, October 04, 2001
2002
- The New Pepito... by Dann Corbit, Winboard Forum, June 24, 2002
- new Pepito version available for download by Carlos del Cacho, Winboard Forum, July 27, 2002
- Config.dat for Pepito by Carlos Pesce, Winboard Forum, July 30, 2002
- New format of Config.dat for Pepito (built from the readme!) by Günther Simon, Winboard Forum, July 30, 2002
- Pepito 1.55 ( Read for fixes) by Nolan Denson, CCC, July 31, 2002
- Siboney = a Pepito clone ?? by Brice Boissel, Winboard Forum, August 06, 2002 [12]
- Pepito 1.54 and learning by Igor Korshunov, Winboard Forum, November 12, 2002
2003
- Deep<9> Is a Clone based of Pepito? Really? by Volker Richey, CCC, March 13, 2003
- Deep9, Pepito and Leo's Qualify by Matthias Gemuh, Winboard Forum, March 13, 2003
2004 ...
- Pepito @ CCT6 After thoughts by Nolan Denson, CCC, February 01, 2004
- Pepito problem by Tord Romstad, Winboard Forum, March 10, 2004
- Pepito 1.59 Windows 64-bit build available by Jim Ablett, CCC, December 20, 2007
External Links
Chess Engine
- Pepito Chess engine on Behance
- Pepito... that other xboard chess engine hosted by Thomas Mayer
- Index of /chess/engines/Norbert's collection/Pepito (Compilation) by Norbert Raimund Leisner, hosted by Kirill Kryukov
- Pepito 1.59 64-bit in CCRL 40/40
Misc
References
- ↑ New winboard engine released! by Carlos del Cacho, CCC, September 18, 2000
- ↑ Pepito Chess engine on Behance
- ↑ Pepito Chess engine on Behance
- ↑ thanx.txt
- ↑ CCT4 - PGN-Download hosted by Volker Richey
- ↑ Siboney is at the moment not available! by Frank Quisinsky, Winboard Forum, May 24, 2002
- ↑ What is the state of Siboney now? by Günther Simon, Winboard Forum, June 26, 2002
- ↑ Siboney = a Pepito clone ?? by Brice Boissel, Winboard Forum, August 06, 2002
- ↑ Re: A Deep question by Carlos del Cacho, Winboard Forum, March 05, 2003
- ↑ The truth about Deep <9> by Thomas Mayer, CCC, March 14, 2003
- ↑ Information by Denis Grafen, CCC, March 15, 2003
- ↑ What is the state of Siboney now? by Günther Simon, Winboard Forum, June 26, 2002