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who conjectures that HAL was "programmed to operate at less than 100% of his capabilities," ? The Waldrop text does not conjecture that
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{{short description|Fictional chess game from Kubrick's 2001: A Space Odyssey}}
{{chess notation}}
[[File:Roesch vs Schlage, 1910.gif|thumb|right|upright=1.25|Animation of the Roesch–Schlage game]]
In the movie ''[[2001: A Space Odyssey (film)|2001: A Space Odyssey]]'', the astronaut [[Frank Poole]] is seen playing chess with the [[HAL 9000]] supercomputer. As HAL is supposed to be infallible, no one is surprised when HAL soundly defeats Poole (though the novel does mention that HAL is programmed only to win 50% of the time in order for there to be some point in the astronauts ever playing). The director [[Stanley Kubrick]] was a passionate chess player, so unlike many chess scenes shown in other films, the position and analysis actually makes sense. The actual game seems to come from Roesch - Schlage, Hamburg 1910, a tournament game between two lesser-known masters.<ref>[http://www.chessgames.com/perl/chessgame?gid=1254321&kpage=1 Roesch vs Willi Schlage (1910)] in [[chessgames.com]]</ref>


'''Poole vs. HAL 9000''' is a [[chess]] game depicted in the 1968 science fiction film ''[[2001: A Space Odyssey (film)|2001: A Space Odyssey]]''. Astronaut [[Frank Poole]] (White) plays the supercomputer [[HAL 9000]] (Black) using a video screen as a [[chessboard]]. Each player takes turns during a game in progress, making their moves orally using [[descriptive notation]] and [[natural language]]. Poole resigns the game once HAL indicates a certain path to [[checkmate]]; however, the move which HAL suggests Frank might make is not {{chessgloss|forced move|forced}}. [[Stanley Kubrick]], director of ''2001'', was an avid chess player.
==Game score==
{{Chess diagram|=
| tright
|
|=
|ql| | | | |rd|kd| |=
| | |pd| |bd|pd|pd|pd|=
|pd| | | | | | | |=
| |pd| | |nd| | | |=
| | | | | |nd| | |=
| | |pl|qd| | | |bd|=
|pl|pl| |pl| |pl|pl|pl|=
|rl|nl|bl|bl| |rl|kl| |=
|Position before 14. Qa8xa6, where the movie picks up the game.}}


The game is shown continuously and legibly for several seconds in a single [[Shot (filmmaking)|shot]]. The board positions and moves made are identical with the conclusion of a real game: Roesch–[[Willi Schlage|Schlage]], Hamburg 1910, which was reported in a 1955 collection of short games by [[Irving Chernev]].<ref>{{cite book |last=Chernev |first=Irving |title=The 1000 Best Short Games of Chess |year=1955 |publisher=Simon and Schuster |isbn=9710851330 |pages=148–149, game No. 322}}</ref> Chess writers have therefore attributed the fictional game fragment to the real one, equating the two and suggesting that the former derived from the latter.{{AN chess|pos=toc}}
Opening: [[Ruy Lopez#Worrall Attack| Ruy Lopez, Worrall Attack]]


==The game==
'''1.e2-e4 e7-e5 2.Ng1-f3 Nb8-c6 3.Bf1-b5 a7-a6 4.Bb5-a4 Ng8-f6 5.Qd1-e2 b7-b5 6.Ba4-b3 Bf8-e7 7.c2-c3 O-O 8.O-O d7-d5'''


According to chess writers, the game depicted in the film is based on a tournament game played between Roesch and Willi Schlage in Hamburg, 1910.<ref name="Soltis">{{cite book |last=Soltis |first=Andrew |title=365 Chess Master Lessons: Take One a Day to be a Better Chess Player |year=2017 |publisher=Batsford |isbn=9781849944342 |page=170}}</ref><ref name="Evans">{{cite web |last=Evans |first=Larry |title=Smart "2001" Computer Didn't Talk the Talk |url=https://www.sun-sentinel.com/news/fl-xpm-1996-03-24-9603200330-story.html |date=March 24, 1996 |publisher=South Florida Sun-Sentinel}}</ref>
This move is a pawn sacrifice.
After White accepts it, Black's pieces can occupy active positions.


[[White and Black in chess|White]]: A. Roesch {{pad|2}} Black: W. Schlage {{pad|2}} [[Chess opening|Opening]]: [[Ruy Lopez]], [[Ruy Lopez#Wormald Variation|Wormald Variation]] (''[[Encyclopaedia of Chess Openings|ECO]]'' C77)<ref name="game">{{cite web |url=http://www.chessgames.com/perl/chessgame?gid=1254321 |title=Roesch vs. Willi Schlage, Hamburg 1910 |website=[[Chessgames.com]]}}</ref><ref name="C77">{{cite web |url=https://chessopenings.com/eco/C77/ |title=C77 |website=chessopenings.com}}</ref>
'''9.e4xd5 Nf6xd5 10.Nf3xe5 Nd5-f4 11.Qe2-e4 Nc6xe5 12.Qe4xa8?'''


'''1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 Nf6 5. Qe2 b5 6. Bb3 Be7 7. c3 0-0 8. 0-0 d5'''
This move deflects the queen, allowing Black to mount a kingside attack.
:The opening is a variation of the Ruy Lopez, followed by a [[pawn (chess)|pawn]] [[sacrifice (chess)|sacrifice]] by Black.
White is also worse if the queen takes one of the knights, which could be answered by N-d3 or Be7-d6. The correct move is 12.d2-d4, to which Black should reply with 12... Bc8-b7.
'''12... Qd8-d3'''


'''9. exd5 Nxd5 10. Nxe5 Nf4 11. Qe4 Nxe5 12. Qxa8{{chesspunc|?}}'''
Threatening 13... Nf4-e2+ 14. Kg1-h1 Ne2-g3+ with mate to follow.
:At 12.Qxa8?, White commits a [[Blunder (chess)|blunder]] by capturing Black's rook using an undefended queen, simultaneously abandoning the defense of his own king. There is widespread agreement among commentators that White's best move at this point is 12.d4{{chesspunc|!}},<ref name="Soltis" /><ref name="Evans" /><ref name="Campbell">{{cite book |last=Campbell |first=Murray |editor-last=Stork |editor-first=David G. |title=HAL's Legacy: 2001's Computer as Dream and Reality |chapter="An Enjoyable Game": How HAL Plays Chess |date=1996 |publisher=MIT Press |isbn=9780262193788 |url=https://web.stanford.edu/class/sts145/Library/campbell.pdf}}</ref><ref name="Matanović">{{citation |editor-last=Matanović |editor-first=Aleksandar |editor-link=Aleksandar Matanović |title=[[Encyclopaedia of Chess Openings]] |publisher=[[Chess Informant]] |location=Yugoslavia |volume=C |edition=2nd |date=1981 |page=412, n. 81 |quote=12.d4 Bb7 13.Qxf4 (13.Qxb7 Ne2+ 14.Kh1 Nxc1 15.Rxc1 Nd3 16.Rf1 c5 {{chesspunc|{{=}}/∞}}) 13...Nd3 14.Qf5 Nxc1 15.Rxc1 g6 16.Qg4 Bg5 17.Rd1 {{chesspunc|+/{{=}}}} |isbn= }}</ref> a move which, if played, would have solidified control of the {{chessgloss|center}}, attacked both black knights, and opened up the development of White's {{chessgloss|queenside}} {{chessgloss|flank}}. Black responded with 12...Qd3!, however, halting the latter.


{{Chess diagram
'''13.Bb3-d1 Bc8-h3!'''
|tright
|
|ql| | | | |rd|kd|
| | |pd| |bd|pd|pd|pd
|pd| | | | | | |
| |pd| | |nd| | |
| | | | | |nd| |
| | |pl|qd| | | |bd
|pl|pl| |pl| |pl|pl|pl
|rl|nl|bl|bl| |rl|kl|
|Position before 14.Qxa6
}}
'''12... Qd3{{chesspunc|!}} 13. Bd1 Bh3!''' (diagram)
:Black capitalizes on White's mistake on move 12. The film shows the game from the position illustrated, with Poole (White) contemplating his 14th move.


'''14. Qxa6?'''
Black also has 13... Bc8-g4, winning a piece after 14. Qa8-b7 Bg4xd1 15. Rf1xd1 Nf4-e2+ 16. Kg1-h1 Ne5-g4 17. Qb7-f3 Qd3xf3 18. g2xf3 Ng4xf2+, or 13... Nf4-h3+ winning the queen after 14. g2xh3 Bc8xh3 with the dual threat of mate & Rf8xQa8. The movie picks up the game here &mdash; see the diagram.
:Spoken by Poole as "queen takes pawn", White abandons the {{chessgloss|long diagonal}} and slips into a {{chessgloss|forced mate|forced checkmate}}. Even after 14.Qb7 c6 15.Qxe7 Bxg2 16.Re1 Nf3+ 17.Bxf3 Qxf3, mate is not far off.


'''14.Qa8xa6?'''
'''14... Bxg2 15. Re1 Qf3'''
:Threatening 16...Nh3{{chessAN|#}}. After Poole's "rook to king one", HAL says: "I'm sorry Frank, I think you missed it: queen to bishop three, bishop takes queen, knight takes bishop, mate." HAL gave Black's queen move from White's perspective, although in [[Descriptive chess notation|descriptive notation]] it should be given from Black's perspective as "queen to bishop six". While HAL describes a checkmate in two moves, Poole could forestall mate two extra moves; for example: 16.Qc8 Rxc8 17.h3 Nxh3+ 18.Kh2 Ng4#.<ref>{{cite web |last=Wall |first=Bill |title=2001: A Chess Space Odyssey |url=http://www.chess.com/article/view/2001-a-chess-space-odyssey |website=[[Chess.com]] |access-date=14 January 2014 |date=22 June 2007 }}</ref>


'''{{chessAN|0–1}}'''
White abandons the long diagonal and moves into a forced mate. Even after 14.Qa8-b7 c7-c6 15.Qb7xe7 Bh3xg2 16.Rf1-e1 Ne5-f3+ 17.Bd1xf3 Qd3xf3, mate is not far off.
:Poole [[resign (chess)|resigns]] without questioning HAL's analysis: "Yeah, looks like you're right. I resign."
{|
|{{Chess diagram
|tleft
|
| | | | | |rd|kd|
| | |pd| |bd|pd|pd|pd
|ql| | | | | | |
| |pd| | |nd| | |
| | | | | |nd| |
| | |pl| | |qd| |
|pl|pl| |pl| |pl|bd|pl
|rl|nl|bl|bl|rl| |kl|
|Final position after 15...Qf3
}}
|[[File:HAL9000.svg|thumb|left|230px|[[HAL 9000|HAL]], after Poole's [[Rules of chess#Resigning|resignation]]: <br />"Thank you for a very enjoyable game."]]
|}
{{clear left}}


[[Arthur C. Clarke]]'s [[2001: A Space Odyssey (novel)|novelization of ''2001'']] also indicated that the astronauts could pass the time by playing various board games with HAL, though no specific game (whether chess or otherwise) was depicted. Unlike the film, Clarke's treatment stated that HAL won only half of games played.
'''14... Bh3xg2 15.Rf1-e1 Qd3-f3'''


{{quote|text=For relaxation he (Dave Bowman) could always engage Hal in a large number of semimathematical games, including checkers, chess, and [[polyomino]]es. If Hal went all out, he could win any one of them; but that would be bad for morale. So he had been programmed to win only fifty percent of the time, and his human partners pretended not to know this. |title=''2001'', p. 100.<ref name="Clarke">{{cite book |last=Clarke |first=Arthur C. |title=2001: a Space Odyssey |year=1968 |publisher=ROC (Penguin) |isbn=9780451452733 |page=100}}</ref> }}
Here HAL, using the [[descriptive chess notation]], says:
''"I'm sorry Frank, I think you missed it. Queen to bishop three, bishop takes queen, knight takes bishop, mate."'', which is inaccurate in two ways. In the first place, the move Qd3-f3 isn't "queen to bishop three" but "queen to bishop six". Secondly, HAL's variation 15.Qd3-f3 16.Bd1xf3 Ne5xf3# does not mention that White could prolong the resistance for a few moves, for example by playing 16.Qa6-h6.
Some conjecture that these two inaccuracies are a very subtle [[foreshadowing]] of either HAL's breakdown or of his deception of the crew.<ref>Clay Waldrop: [http://www.visual-memory.co.uk/amk/doc/0095.html ''The Case For HAL's Sanity'']
</ref>


Unlike Kubrick, Clarke had no particular interest in chess and said that if he did, ''2001'' would not have been made as the two "would have just played chess".<ref name="Wall">{{cite web |last=Wall |first=Bill |title=Stanley Kubrick and Chess |url=http://billwall.phpwebhosting.com/articles/Kubrick.htm |website=Bill Wall's Chess Page}}</ref> Consonant with Clarke's passing mention of polyominoes, a game involving [[pentomino]]es was shot and considered for use in the film, but ultimately passed over<ref name="Tyler">{{cite web |title=How Kubrick Made 2001: A Space Odyssey - Part 4: Jupiter Mission [A] |url=https://www.youtube.com/watch?v=nxDA_PL-XzA |archive-url=https://ghostarchive.org/varchive/youtube/20211215/nxDA_PL-XzA |archive-date=2021-12-15 |url-status=live|website=youtube| date=12 February 2016 }}{{cbignore}}</ref> in favor of the chess game, which Kubrick felt would be more familiar to audiences.<ref>Campbell, .pdf p. 4.</ref> [[Parker Brothers]] had planned a corresponding board game as a [[tie-in]] to the film, which was released as ''Universe'' in 1967; the cover art on the box included a still from the unused cut.<ref>{{cite web |title=Universe |url=https://boardgamegeek.com/boardgame/6547/universe |website=BoardGameGeek |access-date=16 December 2020}}</ref>
Poole resigns without questioning HAL's analysis.

==Interpretation==

[[Murray Campbell]], a member of the team that developed the chess computer [[Deep Blue (chess computer)|Deep Blue]], contributed an article to a book exploring the scientific and cultural implications of the HAL character.<ref name="Campbell" /> Campbell argued that HAL's style of play was more "human" than that of Deep Blue's, in the sense that HAL (Schlage) chose a "nonoptimal" move at 9...Nxd5, which nevertheless stymied his human opponent. In contrast, the real computer Deep Blue used "inhuman" [[brute-force search]]ing and [[minimax]] optimization to always seek the best available move. The book's publication was concurrent with Deep Blue's [[Deep Blue versus Garry Kasparov|two matches]] against the Russian [[Grandmaster (chess)|grandmaster]] [[Garry Kasparov]] in 1996 and 1997; the human player won the first match, while the computer won the latter.

[[Tim Krabbé]] criticized the choice of Roesch–Schlage by way of its [[Chess aesthetics|aesthetics]], calling it "a plain game"; he likewise suggested that the choice of the game implicated Kubrick's own acumen as a player, as well as that of its fictional characters. According to Krabbé, the aesthetic consideration and the simple endgame variation announced by HAL (but not actually played) might explain the character's misuse of descriptive notation when announcing the queen's movement: "A player who would be impressed by that [[Queen sacrifice|Queen's sacrifice]], might be weak enough to make a mistake in its descriptive notation."<ref name="Krabbé">{{cite web |first= Tim |last= Krabbé |author-link= Tim Krabbé |url= http://www.xs4all.nl/~timkr/chess2/schlage.htm |title= Willi Schlage |quote= The only unknown to become immortal twice. |date= 1999 }}</ref>


==See also==
==See also==

* ''[[Blade Runner]]''
* [[Computer chess]]
* [[Computer chess]]
* [[List of chess games]]
* ''[[The Seventh Seal]]''
* [[The Thing (1982 film)|''The Thing'' (1982 film)]]


==References==
==References==
<references/>


{{Reflist}}
==External links==
*[[Murray Campbell|Murray S. Campbell]]: [http://mitpress.mit.edu/e-books/Hal/chap5/five1.html "An Enjoyable Game:"] How HAL Plays Chess in: e-book ''HAL's Legacy'' (1996)
*[[Tim Krabbé]]: [http://www.xs4all.nl/~timkr/chess2/schlage.htm ''Willi Schlage''] ''The only unknown to become immortal twice.'' (1999)


{{Space Odyssey|state=expanded}}
[[Category:Chess games]]
{{Chess|state=collapsed}}
[[Category:Space Odyssey series]]


[[Category:Chess games]]
[[de:Roesch – Schlage, Hamburg 1910]]
[[Category:Space Odyssey]]
[[Category:1968 in chess]]
[[Category:Film scenes]]

Latest revision as of 01:37, 23 October 2024

Animation of the Roesch–Schlage game

Poole vs. HAL 9000 is a chess game depicted in the 1968 science fiction film 2001: A Space Odyssey. Astronaut Frank Poole (White) plays the supercomputer HAL 9000 (Black) using a video screen as a chessboard. Each player takes turns during a game in progress, making their moves orally using descriptive notation and natural language. Poole resigns the game once HAL indicates a certain path to checkmate; however, the move which HAL suggests Frank might make is not forced. Stanley Kubrick, director of 2001, was an avid chess player.

The game is shown continuously and legibly for several seconds in a single shot. The board positions and moves made are identical with the conclusion of a real game: Roesch–Schlage, Hamburg 1910, which was reported in a 1955 collection of short games by Irving Chernev.[1] Chess writers have therefore attributed the fictional game fragment to the real one, equating the two and suggesting that the former derived from the latter.

The game

[edit]

According to chess writers, the game depicted in the film is based on a tournament game played between Roesch and Willi Schlage in Hamburg, 1910.[2][3]

White: A. Roesch   Black: W. Schlage   Opening: Ruy Lopez, Wormald Variation (ECO C77)[4][5]

1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 Nf6 5. Qe2 b5 6. Bb3 Be7 7. c3 0-0 8. 0-0 d5

The opening is a variation of the Ruy Lopez, followed by a pawn sacrifice by Black.

9. exd5 Nxd5 10. Nxe5 Nf4 11. Qe4 Nxe5 12. Qxa8?

At 12.Qxa8?, White commits a blunder by capturing Black's rook using an undefended queen, simultaneously abandoning the defense of his own king. There is widespread agreement among commentators that White's best move at this point is 12.d4!,[2][3][6][7] a move which, if played, would have solidified control of the center, attacked both black knights, and opened up the development of White's queenside flank. Black responded with 12...Qd3!, however, halting the latter.
abcdefgh
8
a8 white queen
f8 black rook
g8 black king
c7 black pawn
e7 black bishop
f7 black pawn
g7 black pawn
h7 black pawn
a6 black pawn
b5 black pawn
e5 black knight
f4 black knight
c3 white pawn
d3 black queen
h3 black bishop
a2 white pawn
b2 white pawn
d2 white pawn
f2 white pawn
g2 white pawn
h2 white pawn
a1 white rook
b1 white knight
c1 white bishop
d1 white bishop
f1 white rook
g1 white king
8
77
66
55
44
33
22
11
abcdefgh
Position before 14.Qxa6

12... Qd3! 13. Bd1 Bh3! (diagram)

Black capitalizes on White's mistake on move 12. The film shows the game from the position illustrated, with Poole (White) contemplating his 14th move.

14. Qxa6?

Spoken by Poole as "queen takes pawn", White abandons the long diagonal and slips into a forced checkmate. Even after 14.Qb7 c6 15.Qxe7 Bxg2 16.Re1 Nf3+ 17.Bxf3 Qxf3, mate is not far off.

14... Bxg2 15. Re1 Qf3

Threatening 16...Nh3#. After Poole's "rook to king one", HAL says: "I'm sorry Frank, I think you missed it: queen to bishop three, bishop takes queen, knight takes bishop, mate." HAL gave Black's queen move from White's perspective, although in descriptive notation it should be given from Black's perspective as "queen to bishop six". While HAL describes a checkmate in two moves, Poole could forestall mate two extra moves; for example: 16.Qc8 Rxc8 17.h3 Nxh3+ 18.Kh2 Ng4#.[8]

0–1

Poole resigns without questioning HAL's analysis: "Yeah, looks like you're right. I resign."
abcdefgh
8
f8 black rook
g8 black king
c7 black pawn
e7 black bishop
f7 black pawn
g7 black pawn
h7 black pawn
a6 white queen
b5 black pawn
e5 black knight
f4 black knight
c3 white pawn
f3 black queen
a2 white pawn
b2 white pawn
d2 white pawn
f2 white pawn
g2 black bishop
h2 white pawn
a1 white rook
b1 white knight
c1 white bishop
d1 white bishop
e1 white rook
g1 white king
8
77
66
55
44
33
22
11
abcdefgh
Final position after 15...Qf3
HAL, after Poole's resignation:
"Thank you for a very enjoyable game."

Arthur C. Clarke's novelization of 2001 also indicated that the astronauts could pass the time by playing various board games with HAL, though no specific game (whether chess or otherwise) was depicted. Unlike the film, Clarke's treatment stated that HAL won only half of games played.

For relaxation he (Dave Bowman) could always engage Hal in a large number of semimathematical games, including checkers, chess, and polyominoes. If Hal went all out, he could win any one of them; but that would be bad for morale. So he had been programmed to win only fifty percent of the time, and his human partners pretended not to know this.

— 2001, p. 100.[9]

Unlike Kubrick, Clarke had no particular interest in chess and said that if he did, 2001 would not have been made as the two "would have just played chess".[10] Consonant with Clarke's passing mention of polyominoes, a game involving pentominoes was shot and considered for use in the film, but ultimately passed over[11] in favor of the chess game, which Kubrick felt would be more familiar to audiences.[12] Parker Brothers had planned a corresponding board game as a tie-in to the film, which was released as Universe in 1967; the cover art on the box included a still from the unused cut.[13]

Interpretation

[edit]

Murray Campbell, a member of the team that developed the chess computer Deep Blue, contributed an article to a book exploring the scientific and cultural implications of the HAL character.[6] Campbell argued that HAL's style of play was more "human" than that of Deep Blue's, in the sense that HAL (Schlage) chose a "nonoptimal" move at 9...Nxd5, which nevertheless stymied his human opponent. In contrast, the real computer Deep Blue used "inhuman" brute-force searching and minimax optimization to always seek the best available move. The book's publication was concurrent with Deep Blue's two matches against the Russian grandmaster Garry Kasparov in 1996 and 1997; the human player won the first match, while the computer won the latter.

Tim Krabbé criticized the choice of Roesch–Schlage by way of its aesthetics, calling it "a plain game"; he likewise suggested that the choice of the game implicated Kubrick's own acumen as a player, as well as that of its fictional characters. According to Krabbé, the aesthetic consideration and the simple endgame variation announced by HAL (but not actually played) might explain the character's misuse of descriptive notation when announcing the queen's movement: "A player who would be impressed by that Queen's sacrifice, might be weak enough to make a mistake in its descriptive notation."[14]

See also

[edit]

References

[edit]
  1. ^ Chernev, Irving (1955). The 1000 Best Short Games of Chess. Simon and Schuster. pp. 148–149, game No. 322. ISBN 9710851330.
  2. ^ a b Soltis, Andrew (2017). 365 Chess Master Lessons: Take One a Day to be a Better Chess Player. Batsford. p. 170. ISBN 9781849944342.
  3. ^ a b Evans, Larry (March 24, 1996). "Smart "2001" Computer Didn't Talk the Talk". South Florida Sun-Sentinel.
  4. ^ "Roesch vs. Willi Schlage, Hamburg 1910". Chessgames.com.
  5. ^ "C77". chessopenings.com.
  6. ^ a b Campbell, Murray (1996). ""An Enjoyable Game": How HAL Plays Chess". In Stork, David G. (ed.). HAL's Legacy: 2001's Computer as Dream and Reality (PDF). MIT Press. ISBN 9780262193788.
  7. ^ Matanović, Aleksandar, ed. (1981), Encyclopaedia of Chess Openings, vol. C (2nd ed.), Yugoslavia: Chess Informant, p. 412, n. 81, 12.d4 Bb7 13.Qxf4 (13.Qxb7 Ne2+ 14.Kh1 Nxc1 15.Rxc1 Nd3 16.Rf1 c5 =/∞) 13...Nd3 14.Qf5 Nxc1 15.Rxc1 g6 16.Qg4 Bg5 17.Rd1 +/=
  8. ^ Wall, Bill (22 June 2007). "2001: A Chess Space Odyssey". Chess.com. Retrieved 14 January 2014.
  9. ^ Clarke, Arthur C. (1968). 2001: a Space Odyssey. ROC (Penguin). p. 100. ISBN 9780451452733.
  10. ^ Wall, Bill. "Stanley Kubrick and Chess". Bill Wall's Chess Page.
  11. ^ "How Kubrick Made 2001: A Space Odyssey - Part 4: Jupiter Mission [A]". youtube. 12 February 2016. Archived from the original on 2021-12-15.
  12. ^ Campbell, .pdf p. 4.
  13. ^ "Universe". BoardGameGeek. Retrieved 16 December 2020.
  14. ^ Krabbé, Tim (1999). "Willi Schlage". The only unknown to become immortal twice.