Author: Eric Oldre
Date: 15:09:30 12/23/05
(Ha ha, just kidding about Rybka, but I thought I'd try to get your attention) :) Hi everyone, I've released Latista 1.4 and it is now available on my website. http://www.oldre.com/chess/latista/ A few interesting things about Latista 1.4. 1) It's the first engine besides scorpio to use Daniel Shawul's Endgame bitbase dll. (that I am aware of) 2) I'm trying a new extension called the horizon threat extension. I'm sure others have done similar things but I'm not sure who. Do to latista's internal board structure and detecting hanging pieces it is pretty cheap. Details in the readme. (copied below) I don't think that 1.4 is significantly stronger than 1.3. But here are the results from the final test I did yesterday and today. (starting from nunn2 positions) Engine Score La 1: Latista [latest] 85.5/160 ········································ 2: Natwarlal 22.0/40 0=11100101100=0=01=1=11101=1010=1==0=101 2: Zeus 22.0/40 111==101=10=1011010000=1===1=10=11001001 4: NagaSkaki 18.5/40 =01=00=0==0=01=1=0=1011000==11===1=1==00 5: NanoSzachy 12.0/40 00=000=10=10000101==0=010=01010==0=00000 160 games played / Tournament finished Site/ Country: ALILAR, United States Level: Blitz 5/1 Hardware: AMD Athlon(tm) 64 Processor 3200+ 2002 MHz with 1,023 MB Memory Operating system: Microsoft Windows XP Professional Service Pack 2 (Build 2600) Here are the contents of the readme file: Latista 1.4 Release Date Dec 23rd, 2005 Homepage http://www.oldre.com/chess/latista/ A chess program written by Eric Oldre. *********** LICENSE **************************** Latista is free for personal use. *********** HOW DO I PLAY? ********************* Latista supports the xboard chess engine protocol. This means that you need a graphical user interface (GUI) in order to be able to play against it. Examples of some interfaces that you can use to play Latista are: -Winboard http://www.tim-mann.org/xboard.html -Arena http://www.playwitharena.com/ *********** HOW STRONG IS LATISTA 1.4 ************* Latista plays on the Free Internet Chess Server (FICS) whenever my computer is free. It plays under the handle "Murderhole". It has a rating of about 2100. If you'd like to play it go to http://www.freechess.org. *********** HOW DOES LATISTA WORK? ************* board representation: Latista is a chess engine built on the concept of rotated bitboards, a concept developed by Robert Hyatt. Information about them can be found at: http://www.cis.uab.edu/info/faculty/hyatt/pubs.html search features: Latista uses a Alpha-Beta search algorithim with several enhancements which include: -Iterative deepening. -Aspiration window. -Null move cutoffs -Quiesent search (captures and promotions only) -Move ordering by: -Hash table entries -Internal Iterative deepening -Static exchange evaluation -Killer moves -Fractional extensions for: -Checks -Pawn to 7th rank. -futility pruning -reductions based on several factors. Evaluation features: -Material -Pawn hash table -Piece square table -Pawn shelter for king -King safety -Pawn Races -Development -Piece Activity *********** WHAT HAS CHANGED SINCE 1.3.0 ************* 1) A new experimental extension has been added, the Horizon threat extension, see below. 2) Mobility evaluation has been tweaked. 3) The tranposition table uses a two layered deep/recent approach. 4) A bug with time management has been fixed which caused losses in some short time controls. 5) Various minor bugs in the search have been fixed, and I'm sure some new ones introduced. 6) Latista can now use in-memory endgame bitbases created by Daniel Shawul, see below. *********** WHAT IS THE HORIZON THREAT EXTENSION ************* The horizon threat extension is an new extension I'm trying. I'm sure other have tried similar ideas, but I'm not sure who. The extension only is evaluated on the last ply before the QSearch. If I make a move that is threatening the oppenents piece, but the static evaluation is below alpha. The oppenent will simply be able to "stand pat" on his turn in the QSearch. Extending by one ply here forces the oppenent to move to see if it can escape the new threat. Here are some examples of moves and positions where the horizon threat extension would be used. Rc5c8 4b1k1/R4pp1/4p2p/1prr4/1P1q1P2/3N4/2PQ1RPP/6K1 b - - 0 3 Pb2b4 6k1/p1qb1p1p/1p4p1/2bB4/5p2/2P5/PP2QnPP/4N1K1 w - - 0 2 Pg6g5 3q4/pp3pkp/5npN/2bpr3/7B/2P2Q2/PP3PP1/R4RK1 b - - 0 1 Nh6g4 8/pp3pkp/1q1b1npN/3pr3/7r/1PP2Q2/P4PP1/R4RK1 w - - 0 4 Ra8b8 r1b2bk1/p1p3pp/2p2n2/3p4/5P2/3BN1P1/PPPK2QP/R6R b - - 0 3 Pc2c4 r1b1r1k1/p1p3p1/2p3p1/2bn4/5P2/4p1Pq/PPP4P/R1K2N1R w - - 0 3 Qc6b5 r3r1k1/p1p3pp/2Q2n2/8/1b3Pb1/3Bp1Pq/P1P4P/R1K2N1R w - - 0 3 I haven't seen a measurable gain yet from this extension. But I like the idea, and it doesn't seem to hurt. And I believe it's not very commonly used. So for now it is part of Latista's search. *********** HOW DO I USE THE ENDGAME BITBASES **************** 1) Download the endgame bitbase dll and data files (available at oldre.com) 2) Put the file in some directory on your PC. Put both the dll and data files in the same directory. 3) Edit the latista.ini file, enter the location of the files in the [egbb] section under "path". *********** SPECIAL THANKS TO **************** The members of the computer chess club. (http://www.talkchess.com/) All the directors of winboard engine tournaments. Jim Ablett for creating the Latista logo image. Daniel Shawul for developing the shared endgame bitbase library. PS. Merry Christmas or Happy Holidays to all my fellow chess programmers!
This page took 0.01 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.