Hans Jack Berliner (January 27, 1929 – January 13, 2017) was a German-born American computer scientist, systems analyst, and chess player of Jewish descent.^[1,12,34] He was born in Berlin, Germany, and died on January 13, 2017, in Riviera Beach, Florida, United States, at the age of 87.^[1,12,34,27] Berliner held a doctorate in mathematics and served as a Professor of Computer Science (and later professor emeritus) at Carnegie Mellon University.^[35,34]

In correspondence chess, he attained the title of ICCF Grandmaster in 1968 and became the 5th World Correspondence Chess Champion, holding the title from 1965 to 1968 according to most sources, or from 1968 to 1971 according to Russian Wikipedia.^[12,34,6] Berliner was particularly renowned for his performance in the 5th World Correspondence Chess Championship, where he won with a score of 14/16 (twelve wins and four draws)—a victory margin of three points that was three times greater than any other champion and an achievement never equaled since.^[6] In over-the-board chess, he held the title of International Master, won the Eastern States Championship in 1955, and represented the United States as a team member at the 10th Chess Olympiad in 1952.^[35]

Beginning in 1972, Berliner engaged in the scientific development of computer chess programs, notably leading the team that directed the construction of the HiTech chess computer.^[35] He was also a published author of works on chess topics, and served as an administrator and board member of the International Chess Players Association.^[27]

Hans Berliner was born on January 27, 1929, in Berlin to a Jewish family, and died on January 13, 2017.^[16] One of his school classmates in Berlin was future Estonian President Lennart Meri, whose father was serving as the Estonian ambassador to Germany.^[2] In 1937, at the age of eight, his family fled Nazi persecution in Germany and emigrated to the United States, settling in Washington, D.C.^[6] He began learning chess at the age of 13, demonstrating extraordinary abilities and rapid progress as the game quickly became his main preoccupation.^[6,1] Berliner was mentioned by Mexican writer Carlos Fuentes in his essay "How I Started To Write", where he was described as "an extremely brilliant boy" with "a brilliant mathematical mind". Fuentes recalled him with the words: "I will always remember his face, dark and trembling, his aquiline nose, and his bright, sunken eyes, with their great sadness, the sensitivity of his hands...".^[6]

In 1949, Berliner earned the title of master, won the District of Columbia Championship (the first of five times he won it), captured the Southern States Championship, and tied with Larry Evans for second place at the New York State Championship. In 1951, he returned to Bad Kreuznach as a soldier and played on the top board of the "Kreuznacher Schachverein 1921" for two years, winning all of his games. At the 1952 Chess Olympiad in Helsinki, he was a member of the United States team on the second reserve board, drawing the only game he played against František Zíta.^[6,7,13] In 1953, he won the New York State Championship, becoming the first non-New Yorker to win the tournament.^[5,6] Sources differ on the year he won the Eastern States Open Championship, placing it in either 1955 or 1956; in the 1956 tournament directed by Norman Tweed Whitaker in Washington, D.C., he finished ahead of William Lombardy, Nicolas Rossolimo, a 13-year-old Bobby Fischer, and Arthur Feuerstein.^[5,6] He also won the 1957 Championship of Champions tournament and became an International Master in 1959.^[5,6] Berliner competed four times in the United States Chess Championship, generally finishing in middle-of-the-table positions: in 1954 in New York, he scored 6½/13 to tie for 8th–9th place behind champion Arthur Bisguier; in 1957–58 in New York, he achieved his best result with a 5th-place finish scoring 7/13; in 1960–61 in New York, he tied for 8th–10th place with 4½/11; and in 1962–63 in New York, he scored 5/11 to share 7th–8th place with Edmar Mednis, with Bobby Fischer winning the other three championships.^[6,40] Demonstrating his talent across various formats of the game, he once gave a six-board blindfold simultaneous exhibition at the Washington Chess Divan, winning all six games against strong local players.

In the 1950s, Berliner took up correspondence chess, a discipline in which he became one of the strongest players in the United States, earned the title of Grandmaster, and was regarded as a perfectionist who constantly sought the best move. He won the United States Correspondence Chess Championship in 1955, 1956, and 1959, achieving a perfect score of 18 wins and zero losses or draws each time. In the 5th World Correspondence Chess Championship, he narrowly won Preliminary Group 1 in 1962–1963 with 11.5 out of 13 points, finishing ahead of Manfred Mädler whom he defeated in a complex bishop endgame.^[14] Berliner went on to win the final round of the 5th World Correspondence Chess Championship (held from 1965 to 1968) with a commanding 3-point margin, scoring 14 out of 16 points with twelve wins and four draws.^[41] His victory as Black against Yakov Borisovich Estrin in this championship—featuring a knight sacrifice in the Fritz Variation of the Two Knights Defense that led to a winning rook endgame—is celebrated as one of the finest games in correspondence chess history. He chose not to defend his world title, but was later persuaded to play in the ICCF 50 Years World Champions Jubilee Tournament from 2001 to 2004 alongside eight other correspondence world champions, where he placed 6th with 3.5 points.^[15] Even in 2005, he retained a correspondence chess rating of 2726, the highest among American players.

In the early 1960s, Berliner began working on chess software while employed at IBM. He resumed his academic studies in 1969 and completed a PhD in computer science at Carnegie Mellon University in 1974 with the dissertation "Chess as Problem Solving: The Development of a Tactics Analyser" under the supervision of Allen Newell. He became a doctor of mathematics, a professor of Artificial Intelligence and computer science, and later professor emeritus of computer systems at Carnegie Mellon University in Pittsburgh. His research in artificial intelligence focused in particular on pattern recognition and the development of the B* best-first search algorithm.^[36] Berliner contributed to the strategy of the early chess program Tech, created programs such as J. Biit, CAPS, and Patsoc, and led the team consisting of Carl Ebeling, Murray Campbell, Gordon Goetsch, and Chris McConnell that developed the HiTech chess computer. In 1988, HiTech made history by defeating Grandmaster Arnold Denker; Berliner was also involved with teams creating supercomputers including Deep Blue, which defeated World Champion Garry Kasparov in 1997, and he continued collaborating on chess computer development in his later years.^[42] In 1979, Berliner developed the backgammon program BKG 9.8, which became the first gaming program to defeat a reigning world champion, Luigi Villa, though Berliner noted that the victory was largely due to random factors from favorable dice rolls.

In 1999, Berliner published a controversial book titled The System, in which he argued that the opening move 1. d4 gives White a clear and decisive advantage in all variations. Although unable to prove this in full detail, he maintained that he had identified a system whose principles could provide proof in every case, citing the Grünfeld Defence variation 1. d4 Nf6 2. c4 g6 3. Nc3 d5 4. cxd5 Nxd5 5. e4 Nxc3 6. bxc3 c5 7. Bc4 Bg7 8. Ne2 Nc6 9. Be3 0–0 10. Rc1 Qa5 11. Kf1 cxd4 12. cxd4 as potentially refuted. The book was met with heavy skepticism and criticism from chess masters, including Mark Dvoretsky, Jeremy Silman, and German Grandmaster Robert Hübner, who reviewed it in ChessBaseMagazin and concluded that it was a belief system rather than one grounded in intellect.^[37]

When he was eight years old, the Jewish Berliner family emigrated from Nazi Germany to the United States. In 1949, he became a master, won the District of Columbia Championship (the first of five victories in that tournament) and the Southern States Championship, and tied for second place with future grandmaster Larry Evans at the New York State Championship. He also won the 1953 New York State Championship (the first victory by a non-New Yorker), the 1956 Eastern States Open directed by Norman Tweed Whitaker in Washington, D.C., finishing ahead of William Lombardy, Nicolas Rossolimo, Bobby Fischer (at age 13), and Arthur Feuerstein, as well as the 1957 Champion of Champions tournament.^[6]

Berliner played for his country's national team at the 10th Chess Olympiad in Helsinki in 1952, drawing his only game on the second reserve board.^[7] Berliner played four times in the U.S. Chess Championship.^[7] In 1954 in New York, he scored 6½/13 to tie for 8th–9th place, in a tournament won by Arthur Bisguier. The last three times Berliner played in the U.S. Championship, the tournament was won by Bobby Fischer. In 1957–58 in New York, Berliner achieved his best result, taking 5th place with a score of 7/13. In 1960–61 in New York, he scored 4½/11, tying for 8th–10th place. Finally, in 1962–63 in New York, he scored 5/11 to tie for 7th–8th place.^[6]

In 1968, Berliner became an ICCF grandmaster, and from 1965 to 1968 he competed in the World Correspondence Chess Championship, which he won. After this, Berliner played no more correspondence games until he entered the "Champion of World Champions" tournament in 2001. Berliner was an emeritus professor of computer science and died in 2017 at the age of 87.^[34]

Berliner is best remembered for his achievements in correspondence play, in which games played by mail can take months or even years to complete. He won the 5th World Correspondence Chess Championship, beginning the final on April 1, 1965, and finishing three years later.^[17] He won with the extraordinary result of 14/16 (twelve wins and four draws), achieving a victory margin of three points, triple that of any other winner in these championships.^[8,1,6] Berliner's game in which he played the Two Knights Defense to defeat Yakov Estrin in that tournament is one of the most famous and important games in correspondence chess, and the opening novelty he introduced in that variation is still considered critically important.^[4,6]

As of March 31, 2005, Berliner still had by far the highest International Correspondence Chess Federation (ICCF) rating of all players in the United States, at 2726 points, which was 84 points above the second-highest rated player.^[9,18] His 2726 rating placed him in third place worldwide on the ICCF list, behind Joop van Oosterom (rated 2741 according to Catalan Wikipedia, or 2777 according to English and Ukrainian Wikipedia) and Ulf Andersson (rated 2736 according to Catalan Wikipedia, or 2737 according to English and Ukrainian Wikipedia).^[10,19] In his 1999 book 'The System', Berliner proposed that the move 1.d4 gives White a large, and probably decisive, advantage.

In 1969, Berliner started a new career by enrolling in the doctoral program at Carnegie Mellon University to study computer science under the supervision of Allen Newell. While a graduate student, Berliner was the subject of a detailed study of chess perception and short-term-memory recall in experiments inspired by the earlier work of de Groot and conducted by Chase and Simon, whose analysis comparing Berliner with a Class A player and a novice formed a basis for their contribution to the theory of chunking in psychology.^[20] Berliner's 1974 PhD dissertation was titled "Chess as Problem Solving: The Development of a Tactics Analyzer".^[21]

His subsequent research at Carnegie Mellon eventually led to the creation of the HiTech chess computer. While programming HiTech, Berliner encountered problems implementing board position evaluation; initially it performed well, but only until it encountered transitions when the balance between the players changed, leading Berliner to conclude that it was weak in board evaluation. He decided to explore the problem by writing an evaluation function for backgammon, resulting in the BKG program (later BKG 9.8), written in the late 1970s on a DEC PDP-10. Early versions of BKG played poorly even against weak players, but Berliner noticed that its critical errors always occurred in transitions. He applied principles of fuzzy logic to smooth the transition between phases, and by July 1979, BKG 9.8 was strong enough to play against reigning world champion Luigi Villa. The program won the match 7–1, becoming the first computer program to defeat a world champion in any game, though Berliner stated that the victory was largely a matter of luck because the computer received more favorable dice rolls.^[11,22,23]

Berliner also developed the B* search algorithm, a best-first graph search algorithm that finds the lowest-cost path from a given starting node to any goal node for use in game tree searching. HiTech was the first computer chess system to reach a 2400 USCF rating level, which English Wikipedia identifies as senior master, while Ukrainian Wikipedia describes it as International Master.^[24] It won the Pennsylvania State Chess Championship several times. Students who worked with Berliner on the project included Carl Ebeling and Murray Campbell. In 1990, Berliner was elected a Founding Fellow of the Association for the Advancement of Artificial Intelligence.^[25] In his later years, Berliner lived in Florida and worked to help develop chess programs.

Berliner retired from Carnegie Mellon University in 1998. In 1998, he self-published a booklet, From the Deathbed of 4. Ng5 in the Two Knights Defense, analyzing the opening of his game with Estrin, as well as attempted improvements upon it by subsequent commentators. In 1999, he published a book explaining his opening repertoire, The System. He claimed that the move 1.d4 gives White a large, and possibly decisive, advantage. He died on January 13, 2017, in Riviera Beach, Florida, fourteen days before his 88th birthday.^[26,27]

In the final of the 5th World Correspondence Chess Championship in 1965, Hans Berliner played as Black against Yakov Estrin in the Two Knights Defense (ECO C57), specifically the Ulvestad Variation. The game concluded with a 0–1 victory for Berliner after the moves 1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. Ng5 d5 5. exd5 b5 6. Bf1 Nd4 7. c3 Nxd5 8. Ne4 Qh4 9. Ng3 Bg4 10. f3 e4 11. cxd4 Bd6 12. Bxb5+ Kd8 13. 0-0 exf3 14. Rxf3 Rb8 15. Be2 Bxf3 16. Bxf3 Qxd4+ 17. Kh1 Bxg3 18. hxg3 Rb6 19. d3 Ne3 20. Bxe3 Qxe3 21. Bg4 h5 22. Bh3 g5 23. Nd2 g4 24. Nc4 Qxg3 25. Nxb6 gxh3 26. Qf3 hxg2+ 27. Qxg2 Qxg2+ 28. Kxg2 cxb6 29. Rf1 Ke7 30. Re1+ Kd6 31. Rf1 Rc8 32. Rxf7 Rc7 33. Rf2 Ke5 34. a4 Kd4 35. a5 Kxd3 36. Rf3+ Kc2 37. b4 b5 38. a6 Rc4 39. Rf7 Rxb4 40. Rb7 Rg4+ 41. Kf3 b4 42. Rxa7 b3.

In a game played in New York on December 23, 1960, between Bobby Fischer as White and Hans Berliner as Black, Fischer brilliantly demonstrated the power of the passed pawn, illustrating Capablanca's principle that a passed pawn increases in strength as the number of pieces on the board decreases. Fischer eliminated the pieces blocking the pawn and subsequently disposed of those hindering its advance, while his constant threats against unprotected pieces and pawns occupied his opponent, gained valuable time, and exhibited an attacking energy reminiscent of Paul Morphy. On move 15, Bd2 threatened 16. g4 and drove away the knight defending the d6 queen's pawn, converting the d5 pawn into a passed pawn after an immediate exchange of pieces. The move 22. Bf4 then drove away the black queen to remove another obstacle in the pawn's path. This December 23, 1960 encounter between Bobby Fischer and Hans Berliner is also documented on YouTube.

Hans Berliner authored The System: A World Champion's Approach to Chess, published by Gambit Publications in 1999. Together with Ken Messere, he also wrote The Fifth Correspondence World Championship, published in 1971 as British Chess Magazine Quarterly No. 14 without an ISBN.

The bibliography includes Hans Berliner's 1979 paper "The B* Tree Search Algorithm. A Best-First Proof Procedure." published in Artificial Intelligence, as well as his 1999 book "The System: A World Champion's Approach to Chess" published by Gambit Publications. Other referenced works include Frank Brady's 1973 publication "Profile of a Prodigy" from David McKay, and Graham Burgess, John Nunn, and John Emms's 2004 book "The Mammoth Book of the World's Greatest Chess Games" from Carroll & Graf. Additionally, the references feature Larry Evans's 1970 work "Modern Chess Brilliancies" published by Fireside, and Árpád Főldeák's 1979 book "Chess Olympiads 1927–1968" from Dover Publications.

External links and identifiers for Hans Jack Berliner include entries under 510006 and 24290. An oral history of Hans Berliner is maintained by ComputerHistory.org. Further coverage includes an obituary noting that chess master and programmer Hans Berliner died at the age of 87.