Nimzo

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|| [[image:Aron_Nimzowitsch.jpg link="http://en.wikipedia.org/wiki/File:Aron_Nimzowitsch.jpg"]] ||~ || **Nimzo**,
a chess program by primary developer [[Chrilly Donninger]], subsequently supported by members of the [[First Vienna Computer Chess Club]] (Nimzo Werkstatt) concerning [[Engine Testing|testing]], [[Knowledge|chess knowledge]], [[Opening Book|opening book]] and hardware. The program was first dubbed //Nimzo-Guernica// in remembrance to [[http://en.wikipedia.org/wiki/Aron_Nimzowitsch|Aron Nimzowitsch]] and as manifest of Chrilly's [[http://en.wikipedia.org/wiki/Anti-war|Anti-war]] engagement <ref>[[http://en.wikipedia.org/wiki/Bombing_of_Guernica|Bombing of Guernica from Wikiepedia]]</ref>. It had its tournament debut at the [[3rd Computer Olympiad#Chess|3rd Computer Olympiad 1991]] and further played the [[DOCCC 1991]] and [[IPCCC 1991]]. At the [[WMCCC 1993]], Nimzo-Guernica aka Nimzo-2 upset [[Gideon|Mephisto Gideon]] <ref>With the help of a sign bug in [[Passed Pawn|passed pawn]] evaluation, see [[Chrilly Donninger]] (**1999**). //Computer machen keine Fehler//. [[Computerschach und Spiele|CSS]] 2/99,  [[http://www.mustrum.de/chrilly/keine_fehler.pdf|pdf]] (German)</ref> and later winner [[Hiarcs]] to lead the pack after five rounds, and finished strong fourth despite 1.5 points out of the last four rounds. ||
|| Aron Nimzowitsch <ref>[[http://en.wikipedia.org/wiki/Aron_Nimzowitsch|Aron Nimzowitsch from Wikipedia]]</ref> ||~ ||^ ||
[[toc]]
=Photos= 
|| [[image:bronsteinchrillyjohan.gif width="638" height="470" link="http://www.thorstenczub.de/aegon.html"]] ||
|| [[David Bronstein]] playing Nimzo by [[Chrilly Donninger]], [[Johan de Koning]] kibitzing, [[Aegon 1997]] <ref>[[David Bronstein]] vs. [[Nimzo]], Photo by [[Thorsten Czub]] from [[http://www.thorstenczub.de/aegon.html|Aegon 1996-97]]</ref> ||

=Nimzo-3=
Guernica and Nimzo-2 were leaf evaluators to spent 60 to 70 percent of its time in [[Evaluation|evaluation]]. The main design criterion for Nimzo-3 was combining the positional play of Nimzo-2 with the [[Tactics|tactical]] strength of a program like [[Fritz]]. Nimzo-3 therefor became a [[Chess Genius|Genius]]/Fritz like program with a complex root evaluation <ref>[[Chrilly Donninger]] (**1996**). //CHE: A Graphical Language for Expressing Chess Knowledge//. [[ICGA Journal#19_4|ICCA Journal, Vol. 19, No. 4]]</ref>, called [[Oracle]] as proposed by [[Hans Berliner]] <ref>[[Hans Berliner]] (**1987**). //Some Innovations Introduced by Hitech//. [[ICGA Journal#10_3|ICCA Journal, Vol. 10, No. 3]]</ref> <ref>[[Hans Berliner]] (**1989**). //Some Innovations Introduced by Hitech//. [[Advances in Computer Chess 5]]</ref>, and which seems to have been first used by [[Kaare Danielsen]]. The oracle approach with very simple, mainly first-order evaluation terms at the leaves, made Nimzo-3 to spent about only 10 to 20 percent on leaf evaluation, yielding in an increased node rate of 400%. 

=CHE=
The [[CHE]] and CHE++ declarative language for expressing chess knowledge using a [[GUI]] was used to incorporate [[Planning |planning]] features within the oracle used <ref>[[http://www.stmintz.com/ccc/index.php?id=198528|CHE docs in English / Nimzo 3 version]] by Mike S., [[CCC]], November 22, 2001</ref>. 

=Commerce=
During the [[WMCCC 1996]], Nimzo was still amateur, but soon went commercial as [[MS-DOS]] program Nimzo 3.5 and the [[Windows]] program Nimzo 2000 distributed by [[Ossi Weiner|Weiner's]] [[Millennium 2000 GmbH]], later released as [[Chess Engine Communication Protocol]] compliant engine WBNimzo. Nimzo98, Nimzo99 were native  [[ChessBase]] engines, followed by Nimzo 7.32 and Nimzo 8 and its derivation [[Schweinehund]] <ref>[[http://www.stmintz.com/ccc/index.php?id=144598|Re: Versions of Nimzo]] by Shep, [[CCC]], December 12, 2000</ref> <ref>[[http://www.stmintz.com/ccc/index.php?id=265975|Re: Nimzo 4]] by [[Manfred Meiler]], [[CCC]], November 19, 2002</ref>. 

=Description=
given in 1999 from the [[ICGA]] tournament site <ref>[[http://www.game-ai-forum.org/icga-tournaments/program.php?id=93|Nimzo's ICGA Tournaments]]</ref>:
|| {{Nimzo is one of the leading professional chess programs. It combines sound positional play with extremely strong tactics. Nimzo-Paderborn is a considerable improved version of the currently commercially available programs Nimzo98, Nimzo99 and Nimzo2000.

Nimzo-Paderborn [[Learning|learns]] automatically from human grandmaster games. It is also equipped with an own Chess-Advice-Language (Che++) which allows strong human players to formulate chess-knowledge. The program can also access in its search [[Endgame Tablebases|endgame databases]]. It therefore searches regularly from the middlegame into won endgames.}} ||
[[#Pruning]]
=Forward Pruning in Nimzo 2.2.1=
Following [[Pruning|forward pruning]] code appears in Nimzo's 2.2.1 search routine <ref>[[http://home.arcor.de/roger.thormann/yacdb.com/nimzo/sr_c.html|Nimzo: sr.c: search-tree handling]] hosted by Roger Thormann</ref> applied at [[Frontier Nodes|frontier nodes]], notably the aggressive [[Richard Lang|Lang]] mode at pre-pre-frontier nodes or below. The source was published along with a foreword by Donninger in 2002 <ref>[[http://home.arcor.de/roger.thormann/yacdb.com/nimzo/vorwort.html|Vorwort von Chrilly Donninger]] (German) hosted by Roger Thormann</ref> :
[[code format="cpp"]]
  if((depth <= 1) && (!extflg) && (score > beta) && (GPtr->hung.w <= KNIGHTHUNG)) {
    return score;
  }

  if(LangModus) {
    if((depth <= 3) && (!extflg) && (score > beta) && (GPtr->hung.w == 0)) {
      return score;
    }
  }
[[code]]
=See also=
* [[Brutus]]
* [[Various Classifications#ChessLegend|Chess legends]]
* [[Hydra]]
* [[Hydra 97]]
* [[WMCCC 1993#NimzoBug|Nimzo's winning white-black bug]], [[WMCCC 1993]]
* [[Schweinehund]]

=Publications=
* [[Chrilly Donninger]] (**1992**). //The Relation of Mobility, Strategy and the Mean Dead Rabbit in Chess//. Heuristic Programming in Artificial Intelligence 3: the third computer olympiad (eds. [[Jaap van den Herik]] and [[Victor Allis]]), pp. 102-111. Ellis Horwood Ltd., Chichester, UK. ISBN 0-13-388265-9
* [[Chrilly Donninger]] (**1993**). //Null Move and Deep Search: Selective-Search Heuristics for Obtuse Chess Programs//. [[ICGA Journal#16_3|ICCA Journal, Vol. 16, No. 3]]
* [[Thomas Mally]] (**1993**). //PC Power in Braille - Nimzo Guernica: Ein PC-Schachprogramm für Blinde//. [[PC Schach]] 3/93 (German) <ref>[[https://en.wikipedia.org/wiki/Braille|Braille from Wikipedia]]</ref>
* [[Chrilly Donninger]] (**1996**). //CHE: A Graphical Language for Expressing Chess Knowledge//. [[ICGA Journal#19_4|ICCA Journal, Vol. 19, No. 4]]

=Forum Posts=
* [[https://groups.google.com/d/msg/rec.games.chess.computer/fON9kA5LPYo/Jpfn6nqs3yYJ|NIMZO 3 ist out now!]] by [[Tom Kerrigan]], [[Computer Chess Forums|rgcc]], July 15, 1996
> [[https://groups.google.com/d/msg/rec.games.chess.computer/fON9kA5LPYo/_utfvtP6RzsJ|Re: NIMZO 3 ist out now!]] by [[Peter Schreiner]], [[Computer Chess Forums|rgcc]], July 19, 1996
* [[https://groups.google.com/d/msg/rec.games.chess.computer/lZshGHUeuxY/Kfef3R7vIkQJ|Re: Nimzo3 - playing strength?]] by [[Helmut Weigel]], [[Computer Chess Forums|rgcc]], August 04, 1996
* [[https://groups.google.com/d/msg/rec.games.chess.computer/o57y2Ldf-ks/rlfhb1TeyYMJ|NIMZO 3 !]] by Komputer Korner, [[Computer Chess Forums|rgcc]], December 01, 1996
* [[http://groups.google.com/group/rec.games.chess.computer/msg/f9c5ab9792a46513|Re: computer chess "oracle" ideas...]] by [[Andreas Mader]], reply to [[Ronald de Man]], [[Computer Chess Forums|rgcc]], April 7, 1997
* [[http://groups.google.com/group/rec.games.chess.computer/msg/2a9279e002cfec4b|Re: Any word on future Nimzo plans]]  by [[Andreas Mader]], [[Computer Chess Forums|rgcc]], March 22, 1998
* [[http://www.stmintz.com/ccc/index.php?id=148289|Nimzo 8 and piece values]] by Matthew Barnett, [[CCC]], January 05, 2001
* [[http://www.talkchess.com/forum/viewtopic.php?t=60404|Nimzo Engines of Millenium Chess System]] by [[Norbert Raimund Leisner]], [[CCC]], June 08, 2016

=External Links=
* [[http://www.game-ai-forum.org/icga-tournaments/program.php?id=93|Nimzo's ICGA Tournaments]]
* [[http://correspondencechess.com/campbell/ham/ham.htm|The Campbell Report - Computer CC Challenge Match]]
* [[http://home.arcor.de/roger.thormann/yacdb.com/nimzo/nimzo_index.html|Nimzo 2.2.1 Source Code]] hosted by Roger Thormann 
* [[http://en.wikipedia.org/wiki/Aron_Nimzowitsch|Aron Nimzowitsch from Wikipedia]]
* [[http://en.wikipedia.org/wiki/Guernica_%28town%29|Guernica (town) from Wikipedia]]
* [[http://en.wikipedia.org/wiki/Bombing_of_Guernica|Bombing of Guernica from Wikiepedia]]
* [[http://en.wikipedia.org/wiki/Guernica_%28painting%29|Guernica (painting) from Wikipedia]]

=References= 
<references />
=What links here?= 
[[include page="Nimzo" component="backlinks" limit="60" ]]
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