Author: Ryan B.
Date: 16:27:01 12/23/05
Go up one level in this thread
On December 23, 2005 at 18:09:30, Eric Oldre wrote: >(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! Gambit Fruit 4bx also uses the Scorpio bitbases. I am very happy that another engine is using them and I hope the list keeps on growing. Ryan
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