|Rainer Feldmann||engine programmer|
|Peter Mysliwietz||engine programmer|
|Heiner Matthias||book author|
|Schach, 1999, Paderborn||30||3.5||7|
|Schach, 1995, Shatin||24||3.0||5|
|Schach, 1992, Madrid||22||4.0||5|
|Schach, 1990, London||Bronze medal||11||5.0||7|
- Description given in 1999:
Zugzwang has been written by Rainer Feldmann and Peter Mysliwietz (until 1996). Rainer Feldmann is a member, Peter Mysliwietz a former member of the research group of Prof. Dr. Burkhard Monien at the University of Paderborn. Zugzwang is a product of an ongoing research in the field of efficient parallel algorithms for optimization problems. In the couse of this research we developed a parallel game tree search algorithm which runs efficiently even on massively parallel systems without any shared memory.
The program started as an OCCAM program for Transputers. In 1992 it played the WCCC in Madrid running on a system with 1024 processors. From 1995 the program was rewritten to C. It now runs efficiently on various hardware platforms as e.g. Power PC based parallel computers or the Cray T3E.
The opening book of Zugzwang is handwritten. No automatic opening book compilation is used. The search algorithm used is the Fail High Reductions algorithm. The program has access to the endgame databases of Ken Thomson.
The most recent tournament played was the Lippstadt Grandmaster Tournament in August 1998, where the program finished second and played at a rate of about 2600 ELO points. The program ran on a Cray T3E with 512 processors (300 MHz) at the John von Neumann Institute for Computing in Juelich, Germany.
- Description given in 1995:
Zugzwang made its first moves in 1989. It won the bronze medal in the 1990 Computer Olympiad, and won the Paderborn (human) Championships in 1991. In the last Computer World Championships in Madrid 1992, Zugzwang, running on a system consisting of 1023 T800 transputers, finished second and was undefeated without playing the eventual Champion, Chess Machine Schroeder. In 1993 Zugzwang had its first victory over a grandmaster. In 1994 Zugzwang was completely rewritten from OCCAM to C (about 20,000 lines of code) and is now portable to a large spectrum of machines including SPARC, SGI, DEC Alpha, I860, 486 and PowerPC. In this year's Championships, Zugzwang will run on a GC-Powerplus distributed system (based on the PowerPC) with at least 96 processors. The opening book contains about 130,000 moves and 1MB transpositional tables are used per processor. Zugzwang uses brute-force alpha-beta search with history tables and killer heuristics. The program searches about 3000 nodes per second per processor on a PowerPC. The search is performed by distributed processors using a distributed algorithm based on the Young Brothers Wait Concept, which gives good results even if as many as 1000 processors are used. In this case the system calculates moves more than 400 times faster than a sequential system.