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'''Zugzwang''' was a massive parallel chess program by [[Rainer Feldmann]] and [[Peter Mysliwietz]] from the [[Paderborn University]], Germany. It won the bronze medal at the [[2nd Computer Olympiad#Chess|2nd Computer Chess Olympiad, London 1990]], and was runner up with three wins and two draws at the [[WCCC 1992]], and won three times the International Paderborn Computer Chess Championships [[IPCCC]]. The Zugzwang team was completed by chess player and [[:Category:Opening Book Author|opening book author]] [[Heiner Matthias]]. Zugzwang was first based on [[^Transputer]] technology with a grid of up to 1024 [https://en.wikipedia.org/wiki/Inmos Inmos] T800 and later T805 processors. Software was developed in the [https://en.wikipedia.org/wiki/Occam_%28programming_language%29 Occam] programming language. Later it was also ported to the [[C|C-programming language]], to run on other hardware architectures such as the [[Cray T3E]] supercomputer in 1999. The [[Young Brothers Wait Concept]] was elaborated exhaustingly by Feldmann et al. <ref>[[Rainer Feldmann]], [[Peter Mysliwietz]], [[Burkhard Monien]] ('''1991'''). ''A Fully Distributed Chess Program''. [[Advances in Computer Chess 6]], [http://www.top-5000.nl/ps/A%20fully%20distribuited%20chess%20program.pdf pdf]</ref><ref>[[Rainer Feldmann]] ('''1993'''). ''Game Tree Search on Massively Parallel Systems'' Phd-Thesis, [http://wwwcs.uni-paderborn.de/fachbereich/AG/monien/PUBLICATIONS/POSTSCRIPTS/feldmann_phd.pdf pdf]</ref>. Zugzwang didn't use [[Null Move Pruning]], but Feldmann's [[Fail-High Reductions]] as well based on the [[Null Move Observation]] <ref>[[Rainer Feldmann]] ('''1997'''). ''Fail-High Reductions.'' [[Advances in Computer Chess 8]], [http://citeseerx.ist.psu.edu/viewdoc/download;jsessionid=4399933A9FAE32A9C855DED714120C66?doi=10.1.1.51.4897&rep=rep1&type=pdf pdf] from [http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.51.4897 CiteSeerX]</ref>. Zugzwang's [[Evaluation|evaluation]] was [[Automated Tuning|tuned]] by [[Simulated Annealing|simulated annealing]] as described in Mysliwietz' Ph.D. thesis <ref> [[Peter Mysliwietz]] ('''1994'''). ''Konstruktion und Optimierung von Bewertungsfunktionen beim Schach.'' Ph.D. thesis (German) </ref>.

* [[Rainer Feldmann]], [[Burkhard Monien]], [[Peter Mysliwietz]], [[Oliver Vornberger]] ('''1989'''). ''Distributed Game-Tree Search''. [[ICGA Journal#12_2|ICCA Journal, Vol. 12, No. 2]] <ref>[[Jonathan Schaeffer]] ('''1989'''). ''Comment on 'Distributed Game-Tree Search'''. [[ICGA Journal#12_4|ICCA Journal, Vol. 12, No. 4]]</ref>