explain xkcd - User contributions [en]

754: Dependencies

2016-01-15T17:55:51Z

173.245.54.62:

{{comic
| number = 754
| date = June 16, 2010
| title = Dependencies
| image = Dependencies.png
| titletext = The prereqs for CPSC 357, the class on package management, are CPSC 432, CPSC 357, and glibc2.5 or later.
}}

==Explanation==
A compiler is a program that converts code, written in a particular programming language, into an executable program. A section of code is said to be dependent on a second segment of code if the results of the first segment are potentially impacted by the second segment. Dependency resolution is part of compiler design, and is the study of determining and correcting dependencies which result in an unwanted, ambiguous, or impossible definition of the dependent section. Requiring that an action occurs if and only if the action has already occurred, like the prerequisite in this comic, is one type of potentially unwanted dependency.

The comic envisions a college computer science course (CPSC432) focusing on "compiler design with dependency resolution" which has itself as a prerequisite. The joke is that the prerequisite is an unresolved dependency, as you must complete this course before you can enroll in it.

This dependency would send a poorly designed compiler into an infinite loop. In real life, the problem is solved by allowing an object to satisfy itself as a prerequisite. This stops the compiler's infinite loop, but may not produce the desired functionality in the program. Another layer of the joke may be that any student who successfully enrolls in the class already knows this solution because they must have employed it in order to get past the apparent infinite recursion in the class prerequisites.

Managing dependencies is useful in other areas of computer science, e.g. {{w|package management}}. Collections of files are known as "packages". A software package might require that a particular operating system patch (a type of package) be installed first. That package might in turn require other packages be installed, and so on. Therefore, a package installer must know the dependencies of a package, and be able to figure out whether any required packages are missing before continuing with the installation.

The title text envisions a course on package management which has itself as a prerequisite, as well as the compiler design course with the impossible prerequisite presented in the main comic (CPSC 432), and glibc2.5 or greater. By looking at the course number it can be observed that CPSC 432 is a fourth year course, and this package management course (CPSC 357) is a third year course. Glibc is a commonly used package on Unix systems, and therefore should be taught in the course. This continues the joke since this course has the following unresolved dependencies:
*Requiring that the course be a prerequisite to itself (CPSC 357).
*Requiring that a course with an unresolved dependency (CPSC 432) be a prerequisite, as CPSC 432 can not be taken.
*Requiring that a fourth year course (CPSC 432) be a prerequisite to a third year course (CPSC 357), as the student should be in their fourth year while taking CPSC 432, and should be in their third year while taking CPSC 357. This is analogous to a lower-numbered package requiring a higher-numbered package.
*Requiring that the student knows part or all of the course material (glibc2.5 or greater) before taking the course, as the student is supposed to learn this information from the course.

==Transcript==
:[A portion of a page from an imaginary course catalog.]
:Page 3
:{| class="wikitable" |
|Department
|Course
|Description
|Prereqs
|-
|Computer science
|CPSC 432
|Intermediate compiler
design, with a focus on

dependency resolution
|CPSC 432
|}
:[The very top of the text for the next course in the table is visible but unreadable.]

==Trivia==
The letter code "CPSC" is the letter code Christopher Newport University, [[Randall]]'s alma mater, uses for Computer Science.

{{comic discussion}}
[[Category:Programming]]
[[Category:Recursion]]

Talk:1052: Every Major's Terrible

2015-12-13T03:33:39Z

173.245.54.62: Info on dates

Panel 1's cueball is in the same pose as Rodin's "The Thinker"

Panel 4 background is the periodic table of elements.

Panel 5, Fowler's Toad emits a noxious secretion that irritates skin and mucous membranes (it was previously thought to cause warts)

Panel 6, Psychology = a serial killer with a chainsaw, Sociology = hobo; Social Psych = hobo serial killer with chainsaw.

Panel 15, LISP, Scheme, and other computer languages with an excess of parentheses.

Panel 16, biohazard symbol

Panel 19, bongos were played by Richard Feynman

Panel 27, fear of snakes, study of reptiles

Panel 28, a picture of a stomach, pun on "stomach" being slang for "tolerate"

Panel 30, words in all lowercase like e.e.cummings

-- [[Special:Contributions/75.103.23.206| 75.103.23.206 ]] 22:04, 7 December 2012‎
:Hobo serial killer with chainsaw? Social psych sounds awesome!
:[[Special:Contributions/24.2.217.188|24.2.217.188]] 22:42, 22 October 2013 (UTC)
----
In panel 22 (History), what's the theme connecting the years 1935, 1969, and 1991?
[[User:Wwoods|Wwoods]] ([[User talk:Wwoods|talk]]) 15:40, 21 May 2013 (UTC)
:1935 is certainly related to some event that lead to the WWII (a quick look at the Wikipedia page for 1935 show that was the year Hitler rearmed Germany), which paved the way to the Cold War. 1969 was Apollo 11, a high moment of the Cold War, as the USA essentially won the race to the Moon. And 1991 was the year that the USSR dissolved, officially ending the Cold War. [[User:Sir labreck|Sir labreck]] ([[User talk:Sir labreck|talk]]) 18:37, 11 August 2015 (UTC)
:1935, Harlem race riot; 1969, race riot in Kuala Lumpur, Malaysia; 1991, Rodney King race riots... 2014-2016??? [[Special:Contributions/173.245.54.62|173.245.54.62]] 03:33, 13 December 2015 (UTC)
----
This explanation is very small for that big comic. I am starting to add the transcript and after that I will do more investigations to that opera. This should be the key to explain all the panels.--[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 19:13, 21 May 2013 (UTC)

:The answer won't lie in the song, trust me. Pirates of Penzance is probably my favorite comic opera out there. Plus Randall gives that the lie in saying you can use the tune from the elements song (a well-known parody) or even Marry Poppins (similar tune, but not exactly the same). I think each panel is just a reference to the words, I don't think that Randall is actually involving The Pirates of Penzance in any way other than the tune. [[Special:Contributions/173.245.52.211|173.245.52.211]] 20:53, 9 December 2013 (UTC)
----
Feynman was also known for being a ladies' man, so the two girls in panel 19 are significant IMHO.
--[[Special:Contributions/141.101.80.117|141.101.80.117]] 13:51, 25 December 2013 (UTC)
----
Needs explanation what does it mean to '''choose a major''', and what '''major''' is in this context. Note every reader is from U.S.A.; different countries have different higher education systems. --[[User:JakubNarebski|JakubNarebski]] ([[User talk:JakubNarebski|talk]]) 10:56, 9 January 2014 (UTC)
:True that. 'Graduation' in Brazil means 'Undergraduation' in the US. [[Special:Contributions/108.162.254.105|108.162.254.105]] 03:51, 1 February 2014 (UTC)
----
"Math's just physics unconstrained by precepts of reality" - that isn't a binary tree, its a [http://en.wikipedia.org/wiki/Bifurcation_diagram bifurcation diagram] from chaos theory. And, sorry, it has nothing to do with the Banach–Tarski paradox - that's just mindless name-dropping.
[[User:Davidbak|Davidbak]] ([[User talk:Davidbak|talk]]) 20:54, 10 February 2014 (UTC)
:Are you sure it is not just an illustration of Banach-Tarski, arguably the most famous example where mathematical reality and (physical) intuition diverge? Why would the verse be illustrated by a bifurcation diagram (which I think, and I might be a bit ignorant here, is a concept pretty much only found in the "applied side" of mathematics, which ''is'' constrained by precepts of reality)? And even if it were a bifurcation diagram, why would the mass of the balls change? (again, I am perhaps showcasing my ignorance; if so, please be gentle) Finally, i would deem the bifurcation explanation a bit too obscure to be the real deal - a panel which is only understood by somewhat specialized mathematicians seems strange to me, especially given that all other frames contain understandable references. [[Special:Contributions/108.162.229.183|108.162.229.183]] 13:38, 9 October 2015 (UTC)
https://www.youtube.com/watch?v=pRexBMPeRTo[[User:Halfhat|Halfhat]] ([[User talk:Halfhat|talk]]) 18:59, 3 April 2014 (UTC)

Panel 30: possibly iambic septameter[[Special:Contributions/141.101.104.154|141.101.104.154]]

1575: Footprints

2015-11-03T22:47:42Z

173.245.54.62: Footprints has appeared before in xkcd, so I made note of that.

{{comic
| number = 1575
| date = September 9, 2015
| title = Footprints
| image = footprints.png
| titletext = "There's one set of foot-p's cause I was totes carrying you, bro!" said Jesus seconds before I punched him.
}}

==Explanation==
The comic is a satirical graphical representation of the inspirational Christian poem "{{w|Footprints (poem)|Footprints}}," which has been recounted in many versions and is of disputed authorship.

The basic idea of the poem is that the narrator looks back at scenes of his life and sees two sets of footprints, his and those of Jesus. During the most difficult times of his life, the narrator sees only one set of footprints and assumes that Jesus had left him during those times. In the climax of the poem, Jesus responds to the narrator that he saw only one set of footprints during the most difficult times of his life because Jesus was carrying him during those times.

The poem is seen by many as overly sentimental and is thus ripe for parody of this kind. The graph mockingly illustrates various times when Jesus or the narrator left the scene, or otherwise gives various reasons why the number of footprints may have been other than two.

"Ducklings {{w|Imprinting (psychology)|imprinted}} on Jesus and followed Him around" is a reference to {{w|Konrad Lorenz}}'s experiments. Three ducklings followed Jesus and the narrator.

"Jesus disappeared for an evening each time a new ''{{w|The Twilight Saga (film series)|Twilight}}'' movie came out" probably means that Jesus went to see the movie and left the narrator alone.

"Got lost and followed our own footprints" may be a reference to "{{w|Winnie-the-Pooh}}" (1926), in which the titular bear and his friend try and hunt a "Woozle" by its footprints, actually following their own round and round a bush, which also seems slightly childish for Jesus as traditionally portrayed. An alternate explanation is that they came to a dead end, and had to double back.

"Rode around with Jesus in captured {{w|Walker (Star_Wars)#All_Terrain_Scout_Transport_.28AT-ST.29|AT-ST}}" is a reference to a two-legged combat "walker" from Star Wars. The implication is that Jesus would have participated in forcibly taking a war machine, which appears somewhat out of character.

The reference at the end to Jesus drowning in a patch of quicksand, and then the narrator simply going home, again subverts the poem's earnestness. "Going home" may be a reference to dying, implying that the narrator died without Christ, or that the narrator and Christ were not traveling anymore.

The title text continues the parody by imagining that Jesus delivers the poem's climactic lines in stereotypical {{w|Bro_(subculture)|"bro"}} speak, a dialect perceived by many to be obnoxious. The reference to punching Jesus is possibly another reference to the poem's perceived excessive sentimentality. Another interpretation is that the narrator, like many people, dislikes usage of this lingo and punched Jesus as a result of this hatred.

Yet another interpretation is that Jesus' obnoxious way of explaining himself indicated dishonesty, meaning he did not in fact carry the narrator during the most difficult parts of his life. The narrator sensed this dishonesty and punched Jesus as a result.

"There's one set of foot-p's cause I was totes carrying you, bro!" can be translated into normal English as "There's one set of footprints because I was definitely carrying you, brother!".

An alternate explanation of some of the oddities of the strip is that "Jesus" is not Jesus Christ, but some guy merely ''named'' Jesus, as is common in some Latin American countries.

Using the Twilight movies as reference points, it can be determined that the span of the graph is from approximately early 2004 to late 2018, with Jesus' death in the second half of 2017.

The poem has appeared in xkcd before, at [[1110: Click and Drag|1110]] with coordinates 0.7601, -58.803.

==Transcript==
{{incomplete transcript}}
A graph with time on the x-axis and numbers 1 through 5 on the y axis, labeled "Sets of footprints". A single red line runs through from left to right, showing different values at different times. Until the very end, the line always returns to the value 2, signifying two sets of footprints in the sand.

*The line starts at the value 2, then dips twice to the value 1. The two troughs are labeled, "Jesus carried me".
*The line then dips once again to the value 1. The trough is labeled, "I carried Jesus".
*The line rises to 3 briefly, and is labeled, "Who was that guy?"
*The line rises to 5 sharply, and then falls in a sharp staircase pattern, labeled "Ducklings imprinted on Jesus and followed him around".
*The line rises to 4, labeled "Got lost and followed our own footprints".
*The line dips for very short periods five times to the value 1. The troughs are labeled, "Jesus disappeared for an evening each time a new <em>Twilight</em> movie came out". The first dip is between "I carried Jesus" and "Who was that guy?", the second between "Who was that guy?" and "Duckings imprinted on Jesus..." and the final three are all between the "Ducklings imprinted on Jesus..." and "Got lost and followed our own footprints".
*The line dips to 1, labeled "Rode around with Jesus in captured AT-ST"
*The line dips and stays level at 1, labeled "Hit quicksand patch. Jesus didn't make it :("
*The line dips to zero at the end, and is labeled "Went home".

{{comic discussion}}
[[Category:Religion]]
[[Category:Language]]
[[Category:Charts]]
[[Category:Animals]]

Talk:291: Dignified

2014-05-20T08:44:29Z

173.245.54.62: Ford again

[[User:Dgbrt|Dgbrt]], just Google "Harrison Ford staples hat" and you'll see what I was talking about. Evidently it was a scene in the "Making of" special.
[[Special:Contributions/173.245.54.62|173.245.54.62]] 08:44, 20 May 2014 (UTC)Harrison Ford fan

972: November

2014-04-27T21:51:42Z

173.245.54.62: /* Explanation */

{{comic
| number = 972
| date = November 2, 2011
| title = November
| image = november.png
| titletext = November marks the birthday of Charles Schulz, pioneer of tongue awareness.
}}

==Explanation==
This comic is a homage to {{w|Charles Schulz}}, the creator of the comic {{w|Peanuts}}, who was born on November 26, 1922. [[:File:tongue awareness.jpg|Here's the comic in question]] by Schulz. xkcd's version has [[Black Hat]] as Linus, and [[Cueball]] as Lucy. In both comics, when you start thinking about your tongue, you can't stop thinking about it. This is similar to the way that if you start thinking about your breathing, you stop breathing unless you consciously think to breathe. Black Hat says "enjoy the next four weeks" sarcastically, knowing Cueball will be uncomfortably aware of his tongue during that time.

[http://fuckyeahexistentialism.tumblr.com/post/852726235/im-aware-of-my-tongue-its-an-awful-feeling A random person on tumblr] also indicates that Schulz's comic is not completely about tongue awareness, instead has deeper meaning about one's existence in the world.

==Transcript==
:[Black Hat and Cueball sit in a room.]
:Black Hat: Did you know November is Tongue Awareness Month?

:[Cueball is suddenly aware of his tongue.]

:[Cueball continues to be aware of his tongue.]

:[Cueball is *still* aware of his tongue.]
:Cueball: I hate you.
:Black Hat: Enjoy the next four weeks.

{{comic discussion}}
[[Category:Comics featuring Black Hat]]
[[Category:Comics featuring Cueball]]