Winboard Forum

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 used the biitbases. I hope more and more engines start using them. Thanks,
Ryan

Hi Eric,

Perfect timing for your release !

Latista 1.40 will be included in the ACCC 1st edition, league Tal, starting today !

see here :

http://aloheac.club.fr/espace_ligue_tal.htm

Best Regards

Arnaud Loh?ac

Hi Eric
Thanks for adding support.
I am almost finished with generating the 5 pieces.
After that i will try to decrease space by using the best available
compression method. Obviously all the 5 pieces can not be loaded into
memory at once, so we have to use it like Nalimov TBs. So in the future
there will be an option to select which bitbases to load in to ram.
I think that using a general cache without loading any tables at startup is not such a bad idea, so i will try this one too.
thanks
daniel

Hello Daniel,

Could you send me the program TSCP that allows to play with your bitbases?

I want to add bitbases to danasah

Thank you and happy noel!

Pedro
e-mail: pedrox@euskalnet.net

_________________
Best wishes,

Pedro Castro

Hi Daniel,

I also want a copy of TSCP that supports your endgame bitbases. It

would be a great help to TwistedLogic if I could support bitbases on it.

Just send it to this e-mail: ed_apostol@yahoo.com.

Thank you very much.

Good luck to Scorpio. I think it would be one of the

program to watch out for this 2006.

Best wishes,

Edsel

hi Daniel

I would like a copy of this too please if possible

could you email it to david.edwards2@NOSPAMblueyonder.co.uk

remove the NOSPAM

Thanks

Geoff

Hi all

Great success for Daniel's bitbases I see

As a tourney organizer, I would request that all engines using Daniel's bitbases would be able to read it exactly in the same format so it would not be needed to have several instances of the bitbases folder on the hard disk.

Olivier

Olivier Deville wrote:Hi all

Great success for Daniel's bitbases I see

As a tourney organizer, I would request that all engines using Daniel's bitbases would be able to read it exactly in the same format so it would not be needed to have several instances of the bitbases folder on the hard disk.

Olivier

Hello Olivier,

I think you mean the same address, much like the Nalimov egtbs.



Later.

Hi

Did anyone get a reply from Daniel ? I got no response

Geoff

Hi

Sorry , i havent checked this page.
I am sending it now.
----------------------------

Please add an option in your engines ini file for the path to the bitbase files(like Nalimov tbs). So that tourney mangers do not have to copy the files for each engine in its own directory. The dll can be shared by many engines at the same time without any problem.

best
daniel

Hi Daniel

Thanks for the reply, not sure what happened but still havent received an email reply, could you try again please ?


email david.edwards2@NOSPAMblueyonder.co.uk

remove the NOSPAM letters


Thanks Geoff

sorry i did not remove NOSPAM before.

here is the download location for anyone.
http://www.geocities.com/dshawul/tscpegbb.zip