explain xkcd - User contributions [en]

1223: Dwarf Fortress

2025-03-10T23:52:39Z

172.71.222.235: /* Explanation */ Secured two links, all others have already been secured, cannot be secured due to lack of certificate, or are dead.

{{comic
| number = 1223
| date = June 10, 2013
| title = Dwarf Fortress
| image = dwarf_fortress.png
| titletext = I may be the kind of person who wastes a year implementing a Turing-complete computer in Dwarf Fortress, but that makes you the kind of person who wastes ten more getting that computer to run Minecraft.
}}

==Explanation==
This comic is a reaction to the recent reveal of a U.S. electronic telecom surveillance program called {{w|PRISM (surveillance program)|PRISM}}, run by the {{w|NSA}}. There is [http://www.guardian.co.uk/world/2013/jun/06/us-tech-giants-nsa-data a Guardian article] about it. PRISM, leaked by a former NSA official, incited some controversy since it provides government access to private data (e-mails, videos, chats, file transfers, etc.). 

''{{w|Dwarf Fortress}}'' is a freeware strategy game in which the player builds a civilization by giving orders to — as opposed to directly controlling — a group of dwarves. It is famous for having a very detailed simulation of its world and for allowing deep micro-management (as well as an incredibly difficult learning curve).

"Big Brother" means "a tyrannical government body that constantly monitors all its citizens." The term comes from the classic dystopian novel ''{{w|Nineteen Eighty-Four}}'' by George Orwell, wherein propaganda videos are narrated by an actor with the stage name of Big Brother and the dystopia's surveillance system is said to be monitored by Big Brother himself.

[[Cueball]] has a discussion with Big Brother ("corporate surveillance state"), in which he mocks Big Brother's interest in the inconsequential activity of playing a video game (''Dwarf Fortress'' in particular) by drawing a parallel between Big Brother's omniscient surveillance of Cueball and Cueball's omniscient surveillance of the dwarves. Big Brother appears to be mortified when it realizes the accuracy of Cueball's comparison.

Informally, a system exhibits ''Turing-completeness'' when it is theoretically capable of executing any algorithm. One of the simplest Turing-complete systems is the {{w|Turing machine}}, a device that manipulates symbols on a strip of tape according to a table of rules — it {{w|Church-Turing thesis|can be proven}} to have the same capabilities as any ordinary programming language. Other very simple systems include {{w|Rule 110}}, {{w|lambda calculus}}, {{w|Conway's game of life}}, and {{w|Brainfuck}}. The reason we don't work with these is because they're a real pain in the ass. Would you rather build a network of spaceships that collide with each other to simulate the successor function, or just write <tt>i := i + 1</tt>?

A common CS nerd challenge is to prove the Turing-completeness of a system that wasn't intended to be that way — games in particular. The usual way to do this is to construct a Turing machine simulator within the system. It has been done for [https://mkv25.net/dfma/map-8269 Dwarf Fortress], [https://web.mat.bham.ac.uk/R.W.Kaye/minesw/infmsw.pdf (infinite) Minesweeper] (pdf), [http://www.toothycat.net/~hologram/Turing/HowItWorks.html Magic the Gathering], [http://www.youtube.com/watch?v=13GOFa1C4e4 Little Big Planet], [http://www.youtube.com/watch?v=1X21HQphy6I Minecraft] ([http://www.youtube.com/watch?v=7sNge0Ywz-M another Minecraft example])1, [http://aurellem.org/vba-clojure/html/total-control.html Pokémon Yellow] (through the elaborate use of many in-game glitches) and [http://cp4space.wordpress.com/2013/04/05/3d-chess-is-turing-complete/ 3D chess]. These kinds of proofs often involve formulating ridiculously complex creations just to simulate a little machine writing symbols on a tape!2

Finally, Randall makes a crack that users will try to nest their Turing-complete computers; after finishing his Turing-complete Dwarf Fortress computer, someone else will try to make the Dwarf Fortress computer run Minecraft (a highly inefficient process that would be a nightmare to coordinate, and would run incredibly slowly).


1 The youtuber legomasta99 even built a whole programmable PC in Minecraft as can be seen [https://www.youtube.com/watch?v=SbO0tqH8f5I here].

2Technically, a computer is not really Turing-complete. A Turing-complete system has to have unlimited space, and that's not possible for a memory-limited computer or any software running inside it. But even if we don't have access to Turing-completeness, we can build a theoretical machine and show how it can be extended indefinitely. In a few of the games, we prove Turing-completeness in infinite variants.


==Transcript==
:[Cueball sits at a desk with a computer, hands on the keyboard, talking to an unseen observer.]
:Cueball: If the corporate surveillance state monitors and controls every aspect of my life...
:Big Brother: We do.
:Cueball: And I play Dwarf Fortress all day...
:Big Brother: You do.
:Cueball: Then you're effectively Dwarf Fortress players watching your dwarves play Dwarf Fortress.
:Big Brother: ... Oh God.
:[Caption below the panel:]
:Big Brother realizes he's trapped in the most tedious possible Hell.

{{comic discussion}}
[[Category:Programming]]
[[Category:Comics featuring Cueball]]
[[Category:Video games]]
[[Category:Politics]]
[[Category:Comics with color]]
[[Category:Fiction]]
[[Category:Minecraft]]

Talk:899: Number Line

2023-12-01T03:01:47Z

172.71.222.235: Added signature

Where does sqrt(-1) go? [[Special:Contributions/67.78.183.206|67.78.183.206]] 19:07, 2 January 2013 (UTC)

:It goes up (literally above 0). A number line can be extended to a complex plane with sqrt(-1) as the unit of measurement in the vertical direction. Or at least, that's where it actually goes. I don't know where Randall would put it. [[Special:Contributions/75.69.96.225|75.69.96.225]] 01:04, 5 March 2013 (UTC)

I'm sorry...are you indicating the ACTUAL location for an IMAGINARY number? {{unsigned|‎74.213.186.41}}

Yes, that's exactly where it is (up to switching clockwise for counterclockwise). There is nothing strange about providing a location for imaginary or complex numbers, the location described is logical, and the adjective 'imaginary' is an artifact of nomenclature and nothing more.[[Special:Contributions/173.48.140.216|173.48.140.216]] 20:40, 30 March 2013 (UTC)

In fact, complex numbers are nearly more real than real ones! Complex analysis really opened my eyes to how much "stepping out" can help in solving problems. The complex notion of analyticity yields fruit in real analysis. Extensions to hypercomplex numbers are weirder, however. --[[User:Quicksilver|Quicksilver]] ([[User talk:Quicksilver|talk]]) 20:27, 17 August 2013 (UTC)

Analyticity must be an imaginary word, and therefore would be found one unit directly above any dictionary. [[Special:Contributions/50.203.89.169|50.203.89.169]] 14:19, 9 October 2013 (UTC)
:Oh my god, I can't believe how hard I laughed at that. Would an imaginary friend actually be above you then? I'm going to use that sometime. [[Special:Contributions/108.162.219.61|108.162.219.61]] 21:25, 24 April 2014 (UTC)
:"I'm sorry, you have reached an imaginary number. Please rotate the phone by 90 degrees and try again."[[Special:Contributions/141.101.98.250|141.101.98.250]] 17:01, 21 October 2017 (UTC)

Is unexplored a map reference? [[User:Halfhat|Halfhat]] ([[User talk:Halfhat|talk]]) 17:53, 13 January 2014 (UTC)

Note that the digits 5 and 6 do not show up on any of the numbers in the comic, reinforcing the fact that the integers 5 and 6 are unexplored. [[User:Blitzer|Blitzer]] ([[User talk:Blitzer|talk]]) 02:34, 15 May 2014 (UTC)
:So the 5th digit of pi can not be known either? [[User:Tharkon|Tharkon]] ([[User talk:Tharkon|talk]]) 03:56, 12 July 2014 (UTC)
:: The ''wha''th digit of pi? [[Special:Contributions/108.162.215.119|108.162.215.119]] 01:59, 1 January 2015 (UTC)
Thank God (or someone else, I'm not choosy) that the SCP link here still works. The rest of the site's gone private. {{unsigned ip|108.162.250.223}}

It appears that Wikipedia had noticed the implications of the title text here. The message now says that it might never be complete, but can be expanded with reliably sourced articles. I'm not 100% sure it's due to Randall's involvement, but I like to think so. --[[Special:Contributions/141.101.104.17|141.101.104.17]] 22:01, 9 December 2014 (UTC)

I am not American, but the linked Wikipedia Article does not support the claims about president's day being observed between the 2 birthdays of Washington and Lincoln in general, but just that in some states Lincoln is also referenced on that day. Even if it was put as a day between these birthdays by definition and on purpose, I do not see the reference here... Especially as this number is given as specific, unlike presidents day, which can occur in a range of days... Someone who knows more of American culture, and also what "observed" (which would link it to holidays....) can mean in English language please revert this. --[[User:Lupo|Lupo]] ([[User talk:Lupo|talk]]) 12:41, 18 September 2019 (UTC)

The link to "bleem" does not work for me, but the word can be found in Urban Dictionary. ——[[Special:Contributions/172.69.63.161|172.69.63.161]] 02:12, 21 August 2020 (UTC)

While 8 is not the "largest even prime", 9 is in fact the ''lowest odd composite'' number. So 8 is the largest in the unbroken line of natural numbers that are even ''or'' prime (or whatever 1 is). [[Special:Contributions/141.101.76.205|141.101.76.205]] 10:48, 18 January 2023 (UTC)

Surely Gird is a reference to Bleem and to the philosophical concepts of Grue and Bleen? Just as they derive from Blue and Green, so we would have Bird and Gleem. [[Special:Contributions/172.71.98.86|172.71.98.86]] 20:33, 29 November 2023 (UTC)

1 pixel <nowiki>~</nowiki> 0.012
start of unexplored zone <nowiki>~</nowiki> 4.381
end of unexplored zone <nowiki>~</nowiki> 6.714
length of unexplored zone <nowiki>~</nowiki> 2.333
coincedence? [[User:Plushiefan4111|plushie fan]] ([[User talk:Plushiefan4111|talk]]) 00:07, 30 November 2023 (UTC)

For f(f(x))=11x, one example is: write x=a*11^b where a%11>0. If a%11 is odd, let f(x)=(a+1)11^b; otherwise a%11 is even, let f(x)=(a-1)11^(b+1).[[Special:Contributions/172.71.222.235|172.71.222.235]] 03:01, 1 December 2023 (UTC)