explain xkcd - User contributions [en]

Talk:2206: Mavis Beacon

2019-09-23T20:14:05Z

Ryanker: Trochees

== So the # key, then? ==

Shifted or not? The implication is that it is, since that's where ‘~’ is. [[Special:Contributions/141.101.99.41|141.101.99.41]] 18:44, 23 September 2019 (UTC)
: On a typical German QWERTZ layout keyboard, the tilde key '~' can/must be entered via AltGr++; alternatively, Ctrl+Alt++ should work when there is no AltGr key. On certain "dead key" keyboard layouts, there even is no single and direct '~' key: To type a tilde, one would have to press AltGr++ followed directly by a space or to double-tap + while holding AltGr. This would mean even more complicated or pretty much impossible key combinations that would be needed to be pressed at the same time. However, holding AltGr or Ctrl+Alt to try and type a tilde would probably cancel out the "single" Alt key necessary for the comic's secret key code. So, once you've managed to type a tilde, it likely wouldn't count any more for the key combo, making it impossible to type this key combination on such keyboard. --[[User:Passerby|Passerby]] ([[User talk:Passerby|talk]]) 19:26, 23 September 2019 (UTC)

The link from Friday's comic to this new one is missing. [[User:N0lqu|-boB]] ([[User talk:N0lqu|talk]]) 19:21, 23 September 2019 (UTC)
: This page was created by the bot only a short while ago. I may be wrong, but I think those links will be set automagically by such bot at some point after the creation of this page. --[[User:Passerby|Passerby]] ([[User talk:Passerby|talk]]) 19:31, 23 September 2019 (UTC)

== Trochees ==
To tie this to a recurring theme in Mr. Munroe's comics... "Mavis Beacon Teaches Typing - Heroes on the half shell." [[User:Ryanker|Ryanker]] ([[User talk:Ryanker|talk]]) 20:14, 23 September 2019 (UTC)

Talk:2066: Ballot Selfies

2018-10-31T15:51:14Z

Ryanker: What harm do laws banning ballot selfies do?

What harm do laws banning ballot selfies do? [[User:Ryanker|Ryanker]] ([[User talk:Ryanker|talk]]) 15:51, 31 October 2018 (UTC)ryanker

832: Tic-Tac-Toe

2017-09-13T21:32:37Z

Ryanker: /* Errors */ Added error 6 about O,X5,O7,X3,O1,X4,... the O6 should be red.

{{comic
| number = 832
| date = December 10, 2010
| title = Tic-Tac-Toe
| image = tic_tac_toe.png
| titletext = The only winning move is to play, perfectly, waiting for your opponent to make a mistake.
}}

==Explanation==
In what follows we will use numpad notation for tic-tac-toe, i.e.:
7|8|9
-+-+-
4|5|6
-+-+-
1|2|3

Pixel values are taken from http://xkcd.com/832_large/.

Each map shows every possible combination of moves which will result in that side winning or tying. It assumes that X moves first, and its optimal move is X7. Any corner would do, so X1, X3 and X9 are also optimal moves. The map for X has a big red X7 (650×650 pixels), and the 8 remaining grids have a smaller (210×210) black X7.

The map for O has more combinations, because in this case X is not assumed to be optimal. All 9 subgrids have one big (210×210) black X and one big red O.

Note that only optimal moves are shown. For example, you can't find a grid beginning with X2 in Map of X, because X2 is not an optimal move.

In map for O you can find a 660×660 grid beginnig with X2. Since the optimal answer is O5, you won't find X2, O8, for example.

;Example 1
The largest red X in Map for X is X7. This means that O must go to cell 7 in Map for O. The largest red O in this subgrid is the center cell O5. Therefore X must magnify cell 5 in the map for X and look for a big red X, which is X3, i.e. in the cell (6, 4) in a 9×9 grid. This can be repeated until one of the players wins or there is a tie.

;Example 2
Download http://xkcd.com/832_large/ and edit it. Delete the upper part. Now you have a picture sized 2040×2150 pixels, with title MAP FOR O.

Assume X used the center cell, X5. You as O must magnify the center cell in the 3×3 map for O. Better still, select that cell and delete everything else. Now you have a picture sized 670×670 pixels, with a big red O7 and a big black X5. You must move O7 this time.
O| |
-+-+-
|X|
-+-+-
| |

Assume X moves X9.
O| |X
-+-+-
|X|
-+-+-
| |

In your drawing program you select cell 9, which is 220×220 pixels. Look for the biggest red O, which is O1. You can see you blocked a winning move.
O| |X
-+-+-
|X|
-+-+-
O| |

Now X, naively, plays X3
O| |X
-+-+-
|X|
-+-+-
O| |X

You select cell 3 in your drawing program, which is 73×73 pixels and looks like this
O| |X
-+-+-
O|X|
-+-+-
O| |X
The O in cell 4 is red, which is your winning move.

;Title text
The title text is a reference to the 1983 movie ''{{w|WarGames}}''. In that movie, by playing Tic-Tac-Toe the AI realizes that some games cannot be won when all the players play flawlessly, and subsequently concludes that the only way to win at the nuclear warfare "game" is not to play.

==Errors==
1) In Map for X, the grid for X7, O9, X1, O4, X3 (i.e. go to Map for X, select cell 9, and then select cell 4) shows the same picture for O5 and O6. Those pictures belong to O6.

[[Image:Tic-Tac-Toe-X-1-8.png]]

The correct pictures should be:
X| |O X| |O
-+-+- -+-+-
O|O| O| |O
-+-+- -+-+-
X|X|X X|X|X

2) In Map for X, the grid for X7, O1, X9, O8, X3 (i.e. go to Map for X, select cell 1, and then select cell 8) shows the same picture for O2 and O5. Those pictures belong to O2. The correct pictures should be:
X|O|X
-+-+-
|O|X
-+-+-
O| |X
=====
X|O|X
-+-+-
| |X
-+-+-
O|O|X

3) In Map for O, the grid for X8, O5, X2, O6 (i.e. go to Map for O, select cell 8, and then select cell 2) shows the same picture for X1 and X3. Those pictures belong to X3. The correct pictures should be:
|X| \ / |X|
-+-+- \ / -+-+-
O|O|O X O|O|O
-+-+- / \ -+-+-
X| |X / \ |X|X

4) In Map for O, the grid for X2, O5, X8, O4 (i.e. go to Map for O, select cell 2, and then select cell 8) shows the same picture for X7 and X9. Those pictures belong to X7. The correct pictures should be:
X|X| \ / |X|X
-+-+- \ / -+-+-
O|O|O X O|O|O
-+-+- / \ -+-+-
|X| / \ |X|

5) In Map for O, the grid for X6, O5, X4, O2 (i.e. go to Map for O, select cell 6, and then select cell 4) shows the same picture for X1 and X7. Those pictures belong to X1.

[[Image:Tic_Tac_Toe-O-6-4.png]]

The correct pictures should be:
X|O|
-+-+-
X|O|X
-+-+-
|O|
=====
\ /
\ /
X
/ \
/ \
=====
|O|
-+-+-
X|O|X
-+-+-
X|O|

6) Typography coloring issue: in Map for O, X5, O7, X3, O1, X4, O6, the O6 should be red to show that it's the latest move, instead of black.

==See also==
http://xkcd.com/832_large/

==Transcript==
:[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. At the smallest divisions some of the moves are too small to see.]

: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.]

{{comic discussion}}
[[Category:Logic]]
[[Category:Comics with color]]

Talk:851: Na

2017-03-24T19:33:31Z

Ryanker: Lovin' Touchin' Squeezin'

Randall actually explains at the top: "I can't ''believe'' I forgot Hey Jude.
I don't get do-overs, but I couldn't resist making [http://xkcd.com/851_make_it_better/ a fixed version]." [[User:Markhurd|Mark Hurd]] ([[User talk:Markhurd|talk]]) 16:29, 6 April 2013 (UTC)
:The "make it better" portion of the URL of the revised comic is probably a reference to additional lyrics from Hey Jude. In light of the fact that that particular joke wouldn't have been available unless he had omitted it from the initial one, it's possible he 'forgot' Hey Jude on purpose.
:[[Special:Contributions/173.21.244.39|173.21.244.39]] 22:40, 10 April 2013 (UTC)
Doesn't Katamari Damacy have nine "na"s, not ten? This is the number I can hear in the song on youtube, and the number in his earlier comic Accident. Am I missing something? --[[Special:Contributions/152.78.168.175|152.78.168.175]] 13:22, 12 May 2013 (UTC)
:Nope. It has 9. "Hey, Jude" wasn't the only thing he missed. [[Special:Contributions/108.162.217.41|108.162.217.41]] 04:14, 8 June 2014 (UTC)
::Actually it depends. In some arrangements there's a leading "Na" at a lower pitch before going into the main sequence, providing the tenth. [[Special:Contributions/108.162.216.13|108.162.216.13]] 20:01, 24 September 2014 (UTC)

Doesn't Batman have 16 na's? I'm pretty sure Im right about that ~JFreund
:Usually, yeah. But if you replace "nana nana nana nana nana nana nana nana" with just "na na na na na na na na" then you get what is seen here. [[Special:Contributions/108.162.217.41|108.162.217.41]] 04:14, 8 June 2014 (UTC)

This is described here as a "flowchart", but I suspect Randall was going for a [http://en.wikipedia.org/wiki/Finite_State_Machine finite state machine]. --[[User:Dfeuer|Dfeuer]] ([[User talk:Dfeuer|talk]]) 08:04, 16 January 2014 (UTC)

Um, I'm not a math person, but this reminds me of Markov Chain a bit?[[Special:Contributions/141.101.105.190|141.101.105.190]] 14:14, 21 February 2015 (UTC)

Doesn't it go "hey hey hey goodbye" instead of "hey hey goodbye" as well? [[Special:Contributions/141.101.99.5|141.101.99.5]] 18:28, 11 March 2015 (UTC) Yeah, I Think I'm Signing Right

This explanation is incomplete and not very good. I'm not American and only by reading through comments here I get to understand that "Na na na ... <x>" are like lyrics extracts from different TV-Show-Songs in the USA? {{unsigned ip|162.158.93.128}}

I added the mention of the title text to the explanation so it's not incomplete anymore. -- [[User:JayRulesXKCD|JayRulesXKCD]] ([[User talk:JayRulesXKCD|talk]]) 1:28, 9 September 2016 (EDT)

What about Na Na Na by My Chemical Romance? Na count of 7 Nas, repeated 6 times in each of 3 choruses, and 11 extra, which adds up to 137 Nas! Or Na Na Na Na Naa by Kaiser Chiefs? Counting Naa as Na, there are 5 Nas, repeated 47 times, for a total of 235 Nas! [[Special:Contributions/162.158.34.82|162.158.34.82]] 11:59, 16 December 2016 (UTC)NaNaNa[[Special:Contributions/162.158.34.82|162.158.34.82]] 11:59, 16 December 2016 (UTC)

Journey's "Lovin' Touchin' Squeezin'" ends with 7 sets of 22 for a total of 154 Nas. [[User:Ryanker|Ryanker]] ([[User talk:Ryanker|talk]]) 19:33, 24 March 2017 (UTC)