832: Tic-Tac-Toe

Explain xkcd: It's 'cause you're dumb.
Revision as of 19:47, 16 December 2012 by Castriff (talk | contribs) (Explanation)
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The only winning move is to play, perfectly, waiting for your opponent to make a mistake.
Title text: The only winning move is to play, perfectly, waiting for your opponent to make a mistake.


Each map shows every possible combination of moves which will result in that side winning. It assumes that X moves first, which is why the map for O has more possible move combinations and, therefore, more subdivisions. The title text is a reference to the 1984 movie WarGames. In that movie, the AI concludes that the only way to win at Tic-Tac-Toe is not to play (since perfect strategy always produces a tie.)


(The comic comprises two large square maps, each divided into nine sections, some of which are further subdivided in the same way. The subdivisions continue down for up to five levels, and the lower map has more tiny diagrams than the upper. The smallest divisions at every scale are completed tic-tac-toe games.)
[Explanatory text:]
Complete map of optimal Tic-Tac-Toe moves
Your move is given by the position of the largest red symbol on the grid. When your opponent picks a move, zoom in on the region of the grid where they went. :Repeat.
Map for X:
(The first square map)
Map for O:
(The second square map)

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This is all wrong. The second move for X, unless O blocked it already, or started off in the centre should be the lower right corner. That way, O will use the centre to block, and then X goes in a third corner, thus sealing the game. 04:59, 23 July 2013 (UTC)

Can you tell which situation you mean? If X starts at 7 and O does not go to 5, then X s a win with the described tactic. There might be other ways to win, but I don't think that matters. --Chtz (talk) 09:11, 23 July 2013 (UTC)
Playing as X, you start in the upper left corner. O plays in any square other than the lower right corner (They might be able to block if they play the centre, depending on whether they anticipate this move). Then, when O blocks the centre, you play the upper right or lower left corner, depending on where O has played before, thus making it impossible to block because they only get one move. The only time this ever fails is when O knows what X is doing after the first move. 19:57, 23 July 2013 (UTC)
If it goes X7, O5, X3, then O must play anywhere but in a corner next (result is symmetric) X has to block and O can hold a draw. Just see the Map for O part. --Chtz (talk) 21:40, 23 July 2013 (UTC)
I don't know the numbers for the squares. There are only nine of them. Could we just refer to them by their positions relative to the rest of the board? 21:44, 23 July 2013 (UTC)
There is more than one way to win. Although X3 does win, as you say, the comic shows an alternative which also has a 100% chance of success. That's right, Jacky720 just signed this (talk | contribs) 00:34, 12 February 2019 (UTC)

There is an error in the drawing when starting with (numpad coordinates) X7, O9, X1, O4, X3: Both O5 and O6 have the same picture. --Chtz (talk) 09:11, 23 July 2013 (UTC)

There is also an error in X7-O1-X9-O8-X3, in which O2 and O5 have the same picture. 02:46, 7 January 2016 (UTC) (And yes, I am reviving a thread from three ago. Happy 2016.)

Tic-Tac-Toe is just a stupid simple game, Randall jokes about that. As the title text says "...waiting for your opponent to make a mistake". And the picture is just a part of this joke.--Dgbrt (talk) 22:04, 23 July 2013 (UTC)

I just don't want to analyze both maps, but I had a college assignment that made me look into Tic Tac Toe strategy, and I think that the explanation should start with "Each map shows every possible combination of moves which will result in that side not losing.". 23:40, 14 January 2014 (UTC)

The quote from War Games is "The only way to win is not to play", and it refers to the game Thermonuclear War, not Tic-Tac-Toe (although that was played earlier in the movie). I don't think the title text was based on this quote, but is only coincidentally similar. (talk) (please sign your comments with ~~~~)

With all due respect, I think the probability that the title text does not reference the movie War Games is so low as to be effectively zero. BTW the whole premise of the resolution of the movie (spoiler alert) is that by playing Tic-Tac-Toe the AI learns the futility of unwinnable 'games'. It then applies this learning to the very real scenarios of thermonuclear war and, realising the futility, stops. Plm-qaz snr (talk) 08:20, 16 August 2014 (UTC)
I think both of you are right in some way, so I fix the text that it do refer to the movie WarGames but to the AI's opinion on the nuclear warfare "game" after learn the concept of unwinnable through Tic-Tac-Toe. Arifsaha (talk) 15:58, 12 September 2014 (UTC)

Those diagrams don't depict every possible situation (e.g. "X2, O8" is missing) (talk) (please sign your comments with ~~~~)

Know any good (but not perfect) tictactoe sims? SilverMagpie (talk) 03:26, 18 April 2017 (UTC)

Could someone please explain how to read the comic?

I feel like I should get it, but I don't know how you're supposed to read this, and the explanation doesn't help. Like, if you want to put down an X somewhere, what do you look at to see what happens in that situation? Mynotoar (talk) 13:35, 6 April 2016 (UTC)

I hope you understand what I added. Demro (talk) 17:38, 6 April 2016 (UTC)
You do what the comic tells you. The comic isn't designed for you to disobey it. That's right, Jacky720 just signed this (talk | contribs) 00:36, 12 February 2019 (UTC)