Pepito... that other xboard chess engine

(This site is best viewed with both eyes open)

15-04-03 -> Andy Möller has set up a new web site where you can get old versions of a somewhat interesting chess engine (IMHO) See the download section at the bottom of this page.

Not much done recently. College keeps me away from computer chess when it used to be the other way round :-). Anyway here it is, a post-CCT5 version but very closely related to the thingy that got smashed there. More details in changes.txt (yeah, another dirty trick to get you grab the new file)

Big thanks to Thomas Lagershausen, Dann Corbit, Nolan Denson & Denis Grafen for putting pressure on me to release this version (I'm lazy).

Current features:

Bitboard infrastructure
Negascout search algorithm
Usual depth extensions to avoid horizon effect (i.e. check, recapture, pawn push...)
Transposition tables, pawn hash tables & evaluation cache
Futility pruning at frontier and prefrontier nodes, razoring
Recursive null move pruning with adaptative R scheme (2/3)
Static exchange evaluator, used for move ordering and also to cull losing captures
Insufficient material draws claiming, as well as 3-rep and 50 move rule.
Early exit in the evaluation if score seems to be out of the a-b window (lazy eval).
Nalimov EGTB format support. Thanks Eugene!
Thinking in opponent's time (pondering)
Compatible to Xboard/Winboard protocol.
"Nearly" compatible to UCI protocol :-)
Book learning.
Three predefined personalities: solid (default), normal, aggressive.

To do list:

Passed pawn eval still sucks...
Native GUI. Well, this is actually in an early stage of development.
Positional learning
Improve time management
Q-checks?
First bug free version
SMP support... just kidding! (or maybe not)

Known bugs/Limitations:

Dieter Eberle reported a weird bug where Pepito missed a mate and played for 3rd repetition instead in a won position. I haven't been able to reproduce it, though it may be related to the UCI mode.
I'm using shorts to store the win/draw/loss statistics in opening books so if you use a collection of more than 65535 games it may overflow a counter here and there.
Book learning doesn't work when running as a UCI engine due to a design flaw in the communication protocol, there's no way to tell whether you're analyzing a position or playing a game.
Actually I fear more unknown bugs. If you happen to come across one of these (normal symptoms... compy crash) don't doubt to write me an email about it, unless you plan to sue me.

Download

Okay, So you got here without reading all the junk I wrote above! I wish you get a corrupted file from this section :-)

	Pepito v1.59, Windows binary:. Built with Intel C++ 7. There are two executables packed in the zip file (with and without profile guided optimization). Thanks to Juan Ignacio Barbosa for providing them. Both seem to be a bit faster than this MVC7 one (Denis Grafen), though your mileage may vary...
	Pepito v1.59, Linux binary: Built with gcc2.95.2.
	Source code: I wouldn't put my nose in here if I were you. You can end up like a mad man, i.e. me, but... you're free to do what you like, aren't you? Bug reports are welcome, bug fixes even more, also chess programming topics, and about basic programming questions... well, depends on the mood.
	Opening book Built from 2600u.pgn with maxply=15 and wpct=30. If you already have the file it's probably faster to build it yourself than to download this crap.
	Old versions Andy Möller's Pepito page. Includes even unreleased binaries along with ancient (caveat: buggy) pepitos that some may want to collect for historical reasons.

Test suite results

(AMD K6 400 MHz, 16 MB hash)

Computer chess links

CCC

A moderated discussion forum about computer chess.

Dark Thought's www pages

Site of Ernst Heinz's chess program. Contains lots of useful information on programming computers to play chess.

Jonathan Schaeffer

Active researcher of brute force search methods, this place is definetly a MUST if you're interested in this kind of stuff. Jonathan is the author of Phoenix (chess) and the world class checkers program Chinook.

Dann Corbit's FTP site

Contains tons of PGN games for public consumption, special builds of existing chess engines, CAP data, test suites and lots of other interesting stuff. Dann is with Colin Frayn, coauthor of the chess engine Beowulf.

Thomas Mayer's Newsticker

Mmmm... I'd better speak well from Thomas since he is hosting this site. There you'll find everything related to Winboard engines: updates, reviews, URLs... He is also the author of Quark and a very nice person :-).

Frank Quisinsky's Newsticker

One of our best loved WB dinosaurs :-) The WB community would not have been the same without Frank's work over these past few years. Thanks!

Crafty

Probably the strongest chess engine you can get for free out there. His author, Bob Hyatt, is one of the guys with more experience in this field (remember Cray Blitz?). And the source code is also available!

Phalanx

My favorite chess program. Dusan Dobes is responsible for lots of my headaches. Phalanx will smash Pepito and whoever gets near by. Source distributed, a bit hard to read though.

Faile

Chess engine written by Adrien Regimbald. I recommend the code of this one for beginners. Crystal clear.

Winboard home page

Well, what to say about Tim... he started it all. His cute GUI is the playground of over 100 chess engines now.

Winboard forum

Here you can ask anything about the subtleties of setting up winboard engines to be ready for head crushing (chess playing, I mean). You may also want to take a look at Aaron Tay's excellent Winboard FAQ.

Lancebot - freelance jobs search engine

This is a past time of mine. It searches all major boards around the web and creates a searchable index with their content. If you are a freelancer looking for a gig, here's your web site.

Bipolar symptoms

I was recently diagnosed with bipolar disorder, kind of scary. Those who know me already are aware that I have allways been nuts all along, so it doesn't make a difference at all.

Carlos del Cacho

September 28th, 2001