Stobor

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Stobor, a private chess engine by Tom Kerrigan, reportedly commercially available under a different name(s). It is named after the bogeyman character in Robert Heinlein's book, Tunnel in the Sky. Stobor is also "Robots" spelled backwards.

=Tournament Play= Stobor played two World Microcomputer Chess Championship, the WMCCC 1995 in Paderborn and the WMCCC 1997 in Paris, and further the IPCCC 1997.

=Design=
 * Board Representation: 0x88
 * Parallel Search: ABDADA
 * Selectivity
 * Check Extensions
 * Null Move Pruning: R=2
 * Quiescence Search: Captures
 * Transposition Table: Thompson (not used in quiescence search)
 * Move Ordering
 * Hash Move
 * MVV/LVA
 * Killer Heuristic
 * History Heuristic

Stobor generates attack information (including X-ray) at the beginning of its evaluation function, utilized for positional considerations.

=History=

The first version of Stobor in 1993 was mainly influenced by the 1978 articles by Peter W. Frey and Larry Atkin on Chess 0.5 in BYTE magazine using attack bitboards. After discussions with Bruce Moreland at ICC, the 1995 rewrite introduced Ferret or GNU Chess 3 like precomputed move tables, while the 1999 rewrite stuck with 0x88. A first version of a parallel search was written in 2002 on a dual Pentium II, optimized in 2016 for 16 cores. In 2004, Stobor's evaluation function was redesigned as mentioned.

=Selected Games= WMCCC 1997, round 4 Stobor - Fritz [Event "WMCCC 1997"] [Site "Paris, France"] [Date "1997.10.28"] [Round "4"] [White "Stobor"] [Black "Fritz"] [Result "1-0"]

1.e4 c6 2.d4 d5 3.Nc3 dxe4 4.Nxe4 Bf5 5.Ng3 Bg6 6.h4 h6 7.Nf3 Nd7 8.h5 Bh7 9.Bd3 Bxd3 10.Qxd3 Qc7 11.Bd2 e6 12.Qe2 Ngf6 13.O-O-O O-O-O 14.Ne5 Nb6 15.Ba5 Rd5 16.b4 Rxa5 17.bxa5 Ba3+ 18.Kb1 Na4 19.Qf3 Bb4 20.Ne2 Qxa5 21.Rd3 Nd5 22.Qxf7 Nac3+ 23.Nxc3 Nxc3+ 24.Rxc3 Bxc3 25.Qxe6+ Kc7 26.Qf7+ Kc8 27.Qb3 Rd8 28.Qe6+ Kb8 29.Qb3 Qb4 30.Qxb4 Bxb4 31.Rd1 Bc3 32.Nf3 Rd5 33.Rd3 Rb5+ 34.Kc1 Bb2+ 35.Kd2 Rxh5 36.Rb3 Rb5 37.Rxb5 cxb5 38.Kd3 Kc7 39.Nh4 h5 40.f4 Bc1 41.Nf5 g6 42.Ne7 g5 43.f5 a6 44.Ke4 Kd6 45.Ng8 h4 46.Nf6 b4 47.Ng4 Bb2 48.Nh6 Ke7 49.Ke5 b5 50.f6+ Ke8 51.Ng4 Kf7 52.Nh2 Ba1 53.Nf3 g4 54.Nxh4 Bc3 55.Nf5 Ba1 56.Nh6+ Ke8 1-0

=See also=
 * Demonology
 * Fiction

=Forum Posts=
 * Kerrigan & Stobor by Kerrigan42, rgcc, January 04, 1996
 * Stobor's BT results... compare? by Tom Kerrigan, rgcc, May 10, 1996
 * Stobor vs. Crafty by Tom C. Kerrigan, rgcc, January 01, 1997
 * Going commercial, maybe by Tom C. Kerrigan, rgcc, March 04, 1997
 * "How To" guide to parallel-izing an engine by Tom Kerrigan, CCC, August 27, 2017

=External Links=
 * Stobor's ICGA Tournaments
 * Stobor from Tom Kerrigan's Home Page

=References=

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