Nimzo

a chess program by primary developer Chrilly Donninger, subsequently supported by members of the First Vienna Computer Chess Club (Nimzo Werkstatt) concerning testing, chess knowledge, opening book and hardware. The program was first dubbed //Nimzo-Guernica// in remembrance to [|Aron Nimzowitsch] and as manifest of Chrilly's [|Anti-war] engagement. It had its tournament debut at the 3rd Computer Olympiad 1991 and further played the DOCCC 1991 and IPCCC 1991. At the WMCCC 1993, Nimzo-Guernica aka Nimzo-2 upset Mephisto Gideon 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. || toc =Photos=
 * Home * Engines * Nimzo**
 * [[image:Aron_Nimzowitsch.jpg link="http://en.wikipedia.org/wiki/File:Aron_Nimzowitsch.jpg"]] ||~ || **Nimzo**,
 * Aron Nimzowitsch ||~ ||^ ||
 * [[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 ||

=Nimzo-3= Guernica and Nimzo-2 were leaf evaluators to spent 60 to 70 percent of its time in evaluation. The main design criterion for Nimzo-3 was combining the positional play of Nimzo-2 with the tactical strength of a program like Fritz. Nimzo-3 therefor became a Genius/Fritz like program with a complex root evaluation, called Oracle as proposed by Hans Berliner , 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 features within the oracle used.

=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 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.

=Description= given in 1999 from the ICGA tournament site :  =Forward Pruning in Nimzo 2.2.1= Following forward pruning code appears in Nimzo's 2.2.1 search routine applied at frontier nodes, notably the aggressive Lang mode at pre-pre-frontier nodes or below. The source was published along with a foreword by Donninger in 2002 : 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
 * Chess legends
 * Hydra
 * Hydra 97
 * 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//. 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)
 * Chrilly Donninger (**1996**). //CHE: A Graphical Language for Expressing Chess Knowledge//. ICCA Journal, Vol. 19, No. 4

=Forum Posts= > [|Re: NIMZO 3 ist out now!] by Peter Schreiner, rgcc, July 19, 1996
 * [|NIMZO 3 ist out now!] by Tom Kerrigan, rgcc, July 15, 1996
 * [|Re: Nimzo3 - playing strength?] by Helmut Weigel, rgcc, August 04, 1996
 * [|NIMZO 3 !] by Komputer Korner, rgcc, December 01, 1996
 * [|Re: computer chess "oracle" ideas...] by Andreas Mader, reply to Ronald de Man, rgcc, April 7, 1997
 * [|Re: Any word on future Nimzo plans] by Andreas Mader, rgcc, March 22, 1998
 * [|Nimzo 8 and piece values] by Matthew Barnett, CCC, January 05, 2001
 * [|Nimzo Engines of Millenium Chess System] by Norbert Raimund Leisner, CCC, June 08, 2016

=External Links=
 * [|Nimzo's ICGA Tournaments]
 * [|The Campbell Report - Computer CC Challenge Match]
 * [|Nimzo 2.2.1 Source Code] hosted by Roger Thormann
 * [|Aron Nimzowitsch from Wikipedia]
 * [|Guernica (town) from Wikipedia]
 * [|Bombing of Guernica from Wikiepedia]
 * [|Guernica (painting) from Wikipedia]

=References= =What links here?= include page="Nimzo" component="backlinks" limit="60"
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