Sometime in the 1970s (?), I read a science fiction story about a human playing a series of chess games against a computer. IIRC, he had to win at least three games.

One was won by finding a book of famous chess games...with a typo in a game. He played that game (e.g., very long book opening) up to the typo, where computer followed by playing the wrong (typo'd) move. The human then won.

One was won by determining the number of plies the computer looked ahead, and setting a trap for that many of plies + 1.

Does anyone know the name of the story (and publication info)?

IIRC, it's not Unicorn Variation, by Zelazny.

I've searched (web, and here), to no avail.

If it was in the 70s, that doesn't help me narrow it down ... during that decade I read essentially all SF mags from mid-40s through 70s :)

  • I mean, it seems to me that winning against a computer chess program by looking ahead one more move than it does isn't really exploiting a bug, it's just being a better chess player. It would always work. Commented Dec 7, 2021 at 20:10
  • @Doug Warren No modern computer chess program looks a fixed number of plies ahead. In many, the set of lines to explore is narrowed at each move, using some sort of scoring function. How deep to look will depend partly on how many viable lines are found. It is true that fixed opening tables are used. Endgames are also subject to special treatmetn in many cases. Commented Dec 8, 2021 at 23:32

1 Answer 1


Might this be The 64-Square Madhouse by Fritz Leiber, first published in the May 1962 issue of If...?

Here're a couple of relevant excerpts from the story.

At the beginning of today's session Sandra had noticed that Bill and Judy were following each game in a very new-looking book they shared jealously between them. Won't look new for long, Sandra had thought.

"That's the 'Bible' they got there," Dave had explained. "MCO-Modern Chess Openings. It lists all the best open-moves in chess, thousands and thousands of variations. That is, what masters think are the best moves. The moves that have won in the past, really. We chipped in together to buy the latest edition—the 13th—just hot off the press," he had finished proudly.

Dave squeezed Sandra's arm hard. Then for once forgetting that he was Dr. Caution, he demanded loudly of Bill and Judy, "Have you two idiots found that column yet? The Machine's thirteenth move is a boner!"

Pinning down the reference with a fingernail, Judy cried, "Yes! Here it is on page 161 in footnote (e) (2) (B). Dave, that same thirteenth move for White is in the book! But Black replies Knight to Queen Two, not Bishop takes Pawn, check. And three moves later the book gives White a plus value."

"What the heck, it can't be," Bill asserted.

"But it is. Check for yourself. That boner is in the book."

"Shut up, everybody!" Dave ordered, clapping his hands to his face. When he dropped them a moment later his eyes gleamed. "I got it now! Angler figured they were using the latest edition of MCO to program the Machine on openings, he found an editorial error and then he deliberately played the Machine into that variation!"

The full story is free to read on Project Gutenberg.

  • 2
    written by a former california state chess champ. Leiber also amazingly presciently predicted a future where everyone wore masks. isn't that incredible? (coming attractions). i never met Leiber but I am sure (about 100%) that i met many players who did play him.
    – releseabe
    Commented Dec 6, 2021 at 10:00
  • Jandorf and Votbinnik, eh? And Sherevsky and Angler...
    – hobbs
    Commented Dec 6, 2021 at 15:15
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    For anyone unfamiliar with it, "boner" as used here is a dated slang term meaning "a foolish and obvious blunder; stupid mistake".
    – V2Blast
    Commented Dec 6, 2021 at 16:26
  • 4

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