explain xkcd - User contributions [en]

626: Newton and Leibniz

2014-01-11T03:17:48Z

Tenrek: Made discussion of calculus more precise.

{{comic
| number = 626
| date = August 21, 2009
| title = Newton and Leibniz
| image = newton_and_leibniz.png
| titletext = YEEEEEEAAAAAAHHHHHH!
}}

==Explanation==
First and foremost {{w|Isaac Newton}} and {{w|Gottfried Leibniz}} both developed {{w|calculus}} independently of each other, as the comic says, about 8 years apart. {{w|Leibniz–Newton calculus controversy|However}}, Newton disputed the fact that Leibniz invented calculus independently of him.

In calculus a {{w|derivative}} is the result of mathematical differentiation: the instantaneous rate of change of a function relative to its argument, and denoted df(x)/dx. Another way to think of the derivative is as a plot of all the slopes of lines tangent to the graph of a function. However, the literary word derivative means developed from something older.

So, the pun is that Newton in the comic is claiming that Leibniz's derivative (used in his development of calculus) is a derivative of (that is, developed from) his derivative (from his earlier development of calculus).

The comic as a whole is mocking the pattern of corny one-liners that {{w|David Caruso}} often spurts out during the opening scenes of {{w|CSI: Miami}}. The one liner is followed by him dramatically pulling off his sunglasses and then the show breaks into the title sequence which starts with the word "YEEEEAAAAAAAH." This has become a [http://knowyourmeme.com/memes/csi-4-pane-comics popular Internet meme] and was used frequently with {{w|Michael Jackson}}'s death.

==Transcript==
:Newton, 1666
:[Newton with long white hair holds up a sheet of paper.]
:Newton: I've invented calculus!
:Leibniz, 1674
:[Leibniz with long black hair holds up a sheet of paper.]
:Leibniz: I've invented calculus!
:Newton: Really? Sounds a little bit...
:[Newton puts on a pair of sunglasses.]
:Newton: ...''Derivative.''

{{comic discussion}}
[[Category:Puts on sunglasses]]
[[Category:Comics featuring real people]]
[[Category:Math]]

626: Newton and Leibniz

2014-01-11T03:11:06Z

Tenrek:

{{comic
| number = 626
| date = August 21, 2009
| title = Newton and Leibniz
| image = newton_and_leibniz.png
| titletext = YEEEEEEAAAAAAHHHHHH!
}}

==Explanation==
First and foremost {{w|Isaac Newton}} and {{w|Gottfried Leibniz}} both invented {{w|calculus}} independently of each other, as the comic says, about 8 years apart. {{w|Leibniz–Newton calculus controversy|However}}, Newton disputed the fact that Leibniz invented calculus independently of him.

In calculus a {{w|derivative}} is the result of mathematical differentiation; the instantaneous change of one quantity relative to another; df(x)/dx. Another way to think of the derivative, is a plot of all the slopes of lines tangent to the original equation. However, the literary word derivative means to develop from something older.

So, the pun is that Newton in the comic is claiming that Leibniz's derivative (meaning: the invention of calculus) is a derivative of (meaning: developed from) his derivative (meaning: calculus). It's even punnier in that Newton started with derivatives as opposed to starting with integrals, as Leibniz did.

The comic as a whole is mocking the pattern of corny one-liners that {{w|David Caruso}} often spurts out during the opening scenes of {{w|CSI: Miami}}. The one liner is followed by him dramatically pulling off his sunglasses and then the show breaks into the title sequence which starts with the word "YEEEEAAAAAAAH." This has become a [http://knowyourmeme.com/memes/csi-4-pane-comics popular Internet meme] and was used frequently most recently with {{w|Michael Jackson}}'s death.

==Transcript==
:Newton, 1666
:[Newton with long white hair holds up a sheet of paper.]
:Newton: I've invented calculus!
:Leibniz, 1674
:[Leibniz with long black hair holds up a sheet of paper.]
:Leibniz: I've invented calculus!
:Newton: Really? Sounds a little bit...
:[Newton puts on a pair of sunglasses.]
:Newton: ...''Derivative.''

{{comic discussion}}
[[Category:Puts on sunglasses]]
[[Category:Comics featuring real people]]
[[Category:Math]]

Talk:230: Hamiltonian

2014-01-01T08:56:18Z

Tenrek:

I don't agree with the title's explanation. IMO the title refers to the fact the "sudden rush of perspective" happens to Cueball also when he is making love, but starts to think about the algorithms. {{unsigned ip|‎37.128.6.132}}

Fixed. [[User:Tenrek|Tenrek]] ([[User talk:Tenrek|talk]]) 08:56, 1 January 2014 (UTC)

230: Hamiltonian

2014-01-01T08:55:31Z

Tenrek: Added precision.

{{comic
| number = 230
| date = March 2, 2007
| title = Hamiltonian
| image = hamiltonian.png
| titletext = The problem with perspective is that it's bidirectional.
}}

==Explanation==
[[Cueball]], presumably in class, decides that the subject of {{w|Mathematical_optimization|optimizing}} {{w|Routing|routing algorithms}} is not important in the larger context of life and love. However, he later realizes while in bed with [[Megan]] that there is a flaw in the proof presented, and suddenly wants to focus on the mathematics again, in a humorous reversal of his position about what is meaningful.

In graph theory, a {{w|Hamiltonian_path|Hamiltonian path}} is a path that connects all the vertices (nodes) and passes through each one exactly once. (Think connect the dots with rules!) A Hamiltonian cycle is a Hamiltonian path such that the final vertex is adjacent to the initial one (intuitively, it "begins and ends with the same vertex," but recall that paths are required to only pass through each vertex once). The presenter is using graph theory to optimize a routing algorithm by solving a {{w|Hamiltonian_path_problem|Hamiltonian path problem}}. Cueball's realization is that the proof he had followed in part actually requires a Hamiltonian cycle, not just a path, so the presenter's proof of the existence of a Hamiltonian path is insufficient to solve the problem.

The title text plays on a dual interpretation of bidirectional: just as any graph cycle can be traversed in two directions, a change in perspective can be traversed in two directions (from mathematics to love, and then from love to mathematics).

==Transcript==
:Lecturer: And therefore, based on the existence of a Hamiltonian path, we can prove that the routing algorithm gives the optimal result in all cases.
:Cueball: Oh my God.

:[Close-up of Cueball.]
:Offscreen: What? What is it?
:Cueball: A sudden rush of perspective. What am I doing here? Life is so much bigger than this!

:[Cueball running out of room.]
:Cueball: I have to go.

:[Cueball enters darkened room, where Megan waits by window.]
:[Cueball and Megan embrace...]

:[...and get into bed.]

:[A heart appears over the supine bodies.]
:Megan: Ohh...
:''grip''

:Cueball (out of frame): Wait a moment.
:Megan (out of frame): What is it?

:[Silence.]

:Cueball (out of frame): His proof only holds if there's a Hamiltonian cycle as well as a path!
:Megan (out of frame): ...excuse me?
:Cueball (out of frame): Paper, I need some paper. Hey, do you mind if I jot down some notes on your chest?

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Comics with color]]
[[Category:Sex]]
[[Category:Math]]
[[Category:Romance]]

427: Bad Timing

2013-12-30T05:55:39Z

Tenrek: "Falling out of the basket" seems more appropriate for a hot air balloon than "ejected from the capsule."

{{comic
| number = 427
| date = May 23, 2008
| title = Bad Timing
| image = bad_timing.png
| titletext = Protip: Even without the red spiders, never have that conversation halfway through a balloon ride.
}}

==Explanation==
[[Cueball]] breaks up with [[Megan]] in the middle of a {{w|hot air balloon}} ride. Then {{w|Non sequitur (literary device)|the red spiders attack}}.

The red spiders are among the earliest xkcd [[characters]], first appearing in [[8: Red spiders]].

As the protip in the title text states, a break-up conversation while you are stranded in an inaccessible location is very poor manners. Also, the suggestion may be interpreted that breaking up in a hot air balloon is a very dangerous way to do it; the reaction may result in one or both parties falling out of the basket.

==Transcript==
:[Cueball and Megan, flying in a hot air balloon.]
:Cueball: I like you. I'm just not feeling the relationship.
:Cueball: I'm sorry.
:Cueball: It's just bad timing. Me with my classes, you with your work, the spiders...
:Megan: The what?
:[Red Spiders crowd onto balloon, causing it to fall.]

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Red Spiders]]
[[Category:Comics with color]]
[[Category:Romance]]
[[Category:Protip]]

Talk:1310: Goldbach Conjectures

2013-12-30T05:53:06Z

Tenrek: Created page with "If a bot can create the text I read here, we have made great strides in artificial intelligence. Probably a human editor forgot to change the "incomplete/incorrect" heading. ~~~~"

If a bot can create the text I read here, we have made great strides in artificial intelligence. Probably a human editor forgot to change the "incomplete/incorrect" heading. [[User:Tenrek|Tenrek]] ([[User talk:Tenrek|talk]]) 05:53, 30 December 2013 (UTC)

399: Travelling Salesman Problem

2013-12-27T10:57:28Z

Tenrek: Corrected remarks about efficiency of solutions to travelling salesman problem, and made discussion of the problem slightly more precise.

{{comic
| number = 399
| date = March 21, 2008
| title = Travelling Salesman Problem
| image = travelling_salesman_problem.png
| titletext = What's the complexity class of the best linear programming cutting-plane techniques? I couldn't find it anywhere. Man, the Garfield guy doesn't have these problems...
}}

==Explanation==
The {{w|Travelling salesman problem}} is a classic problem in computer science. An intuitive way of stating this problem is that given a list of cities and their pairwise distances, the task is to find the shortest possible route that visits each city exactly once and then returns to the origin city. A naive solution solves the problem in {{w|Factorial|O(n!) time}} (where n is the size of the list), simply by checking all possible routes, and selecting the shortest one. A more efficient {{w|Dynamic programming|dynamic programming}} approach yields a solution in O(n22n) time.

The joke is that the computer salesman selling on {{w|eBay}} does not have to worry about this problem since he does not need to travel, to which the travelling salesman angrily responds "shut the hell up".

The title text wonders about the time complexity of the {{w|Cutting-plane method}}, which is sometimes used to solve optimization problems.
The last sentence suggests the down side for Randall of writing comics about computer science; he sometimes encounters problems to which he cannot find the answer, whereas authors of simpler comics such as {{w|Garfield}} do not have this problem. This is also likely a reference to [[78: Garfield]], which parodies Garfield's simplicity.

This is so far the only comic featuring the [[Brown Hat]] character.

Also see previous strip [[287: NP-Complete]].

==Transcript==
:[There is a linked black web, with a path in red; it may be a map of the USA.]
:Brute-force solution:O(n!)
:[The web continues in this one. A man with a hat and a case is drawing it.]
:Dynamic programming algorithms: O(n22n)
:[Another man, with a hat too, is at a computer, looking back over the chair.]
:Selling on eBay: O(1)
:Computer salesman: Still working on your route?
:Drawing salesman: Shut the hell up.

{{comic discussion}}
[[Category:Comics with color]]
[[Category:Comics featuring Brown Hat]]
[[Category:Math]]

1307: Buzzfeed Christmas

2013-12-24T03:13:26Z

Tenrek: Changed "Gold rings" to "Golden rings," in accordance with song lyrics.

{{comic
| number = 1307
| date = December 22, 2013
| title = Buzzfeed Christmas
| image = buzzfeed christmas.png
| titletext = The 6 Weirdest Objects The Buzzfeed Writers Are Throwing Out Their Windows At Us
}}

==Explanation==
{{incomplete|This is a new comic}}

Christmas caroling is a tradition in which groups of singers travel from house to house, singing {{w|Christmas_carol|carols}}.

These carolers are in front of the [http://www.buzzfeed.com/ BuzzFeed] offices singing the {{w|The_Twelve_Days_of_Christmas_(song)|The Twelve Days of Christmas}}, which contains:

: On the twelfth day of Christmas, my true love gave to me.
: 12 Drummers drumming
: 11 Pipers piping
: 10 Lords a-leaping
: 9 Ladies dancing
: 8 Maids a-milking
: 7 Swans a-swimming
: 6 Geese a-laying
: 5 Golden rings
: 4 Calling birds
: 3 French hens
: 2 Turtle doves
: And a partridge in a pear tree.

The carolers changed the lyrics to match the headlines of the topics published by BuzzFeed, which usually contain a number and a superlative (for example, ''13 Worst Plane Crashes of the Decade'').

This method of writing headlines is used by several other news sites, because it is known to generate a lot of visits (and ad revenue). [[Randall]] has touched on this subject before in [[1283: Headlines]].

Carolers are usually rewarded with a gift, but the BuzzFeed writers probably didn't appreciate the song, because they threw weird stuff at them (which the carolers used in their 7th verse).

==Transcript==
:[Carolers singing.]
:Carolers: 12 Best drummers of ''all time''
:Carolers: 11 Pipers whose jaw-dropping good piping will make you cry
:Carolers: You won't ''believe'' what these 10 lords leap over
:[Comic caption]
:Carolers outside the Buzzfeed offices perform "12 Weird things I ''actually got'' for Christmas"

{{comic discussion}}
[[Category:Christmas]]
[[Category:Music]]
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring Hairy]]

621: Superlative

2013-12-18T23:03:26Z

Tenrek: Changed "impersonates" to "plays," as this is more common for describing what an actor does.

{{comic
| number = 621
| date = August 10, 2009
| title = Superlative
| image = superlative.png
| titletext = Stay while I recount the crazy TF2 kill I managed yesterday, my friends.
}}

==Explanation==
The comic parodies a famous advertisement campaign for the {{w|Dos Equis}} beer brand. In the campaign, {{w|Jonathan Goldsmith}} plays "{{w|The Most Interesting Man in the World}}", a suave elderly gentleman with astonishing abilities and life experiences. The campaign's format generally includes the narrator presenting hyperbolic descriptions of the man's accomplishments, followed by the man delivering his signature catchphrase, "I don't always drink beer, but when I do, I prefer Dos Equis.", which has been widely adopted as an {{w|internet meme}}.

In the comic, [[Cueball]] plays the antithesis of the protagonist in the campaign: the ''least'' interesting man in the world. Unlike the stories in the advertisement, his affairs tend to bore the listeners. Being the generic everyman, he possesses no outstanding capabilities at all. While the original is said to "speak French... in Russian", Cueball seems to have forgotten his French altogether. He also has apparently nothing of interest to tell, either in real life or in his blog. Instead, he will talk away about his weird dreams and his success in video games. Moreover, he is unable to stand too much beer and therefore absolutely ill-qualified to advertise it.

The title text is a reference to the slogan of the campaign "Stay thirsty, my friends." It also references {{w|Team Fortress 2}} (TF2), a multi-platform, multi-player {{w|First-person shooter}} game.

==Transcript==
:He has dreams.
:[Cueball is gesturing to Megan.]
:Cueball: I was in this weird cross between work and my old house...
:Which he'll tell you ''all'' about.
:He can speak French.
:Or could in high school, anyway.
:A little.
:Cueball: Man, I knew all these tenses and stuff once.
:His blog has four posts, all apologies for not posting more.
:[Cueball is sitting at a desk, typing.]
:Cueball: Sorry, I've been trying to think of stuff to put here.
:He is
:The least interesting man in the world.
:[Cueball is sitting at a table. Megan and Ponytail are paying no attention to him.]
:Cueball: I don't always drink beer, but when I do, I stick to a glass or two. Any more and I feel sick.

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Ponytail]]
[[Category:Internet]]
[[Category:Video games]]

621: Superlative

2013-12-18T22:59:49Z

Tenrek: Changed "absolute counterpart" to "antithesis" (counterpart implies supposition, not opposition).

{{comic
| number = 621
| date = August 10, 2009
| title = Superlative
| image = superlative.png
| titletext = Stay while I recount the crazy TF2 kill I managed yesterday, my friends.
}}

==Explanation==
The comic parodies a famous advertisement campaign for the {{w|Dos Equis}} beer brand. In the campaign, {{w|Jonathan Goldsmith}} plays "{{w|The Most Interesting Man in the World}}", a suave elderly gentleman with astonishing abilities and life experiences. The campaign's format generally includes the narrator presenting hyperbolic descriptions of the man's accomplishments, followed by the man delivering his signature catchphrase, "I don't always drink beer, but when I do, I prefer Dos Equis.", which has been widely adopted as an {{w|internet meme}}.

In the comic, [[Cueball]] impersonates the antithesis of the protagonist in the campaign: the ''least'' interesting man in the world. Unlike the stories in the advertisement, his affairs tend to bore the listeners. Being the generic everyman, he possesses no outstanding capabilities at all. While the original is said to "speak French... in Russian", Cueball seems to have forgotten his French altogether. He also has apparently nothing of interest to tell, either in real life or in his blog. Instead, he will talk away about his weird dreams and his success in video games. Moreover, he is unable to stand too much beer and therefore absolutely ill-qualified to advertise it.

The title text is a reference to the slogan of the campaign "Stay thirsty, my friends." It also references {{w|Team Fortress 2}} (TF2), a multi-platform, multi-player {{w|First-person shooter}} game.

==Transcript==
:He has dreams.
:[Cueball is gesturing to Megan.]
:Cueball: I was in this weird cross between work and my old house...
:Which he'll tell you ''all'' about.
:He can speak French.
:Or could in high school, anyway.
:A little.
:Cueball: Man, I knew all these tenses and stuff once.
:His blog has four posts, all apologies for not posting more.
:[Cueball is sitting at a desk, typing.]
:Cueball: Sorry, I've been trying to think of stuff to put here.
:He is
:The least interesting man in the world.
:[Cueball is sitting at a table. Megan and Ponytail are paying no attention to him.]
:Cueball: I don't always drink beer, but when I do, I stick to a glass or two. Any more and I feel sick.

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Ponytail]]
[[Category:Internet]]
[[Category:Video games]]

593: Voynich Manuscript

2013-12-12T21:28:40Z

Tenrek: Changed "analog" to "analogue," improved some grammar and sentence structure, noted misuse of pronoun "your" in the last frame.

{{comic
| number = 593
| date = June 5, 2009
| title = Voynich Manuscript
| image = voynich_manuscript.png
| titletext = Wait, is that the ORIGINAL voynich manuscript? Where did you GET that? Wanna try playing a round of Druids and Dicotyledons?
}}

==Explanation==
As the comic explains, the {{w|Voynich Manuscript}} is a very detailed book written in an unknown script, describing plants and recipes, most of which lack a real-world analogue. Over the past few decades, linguists and cryptographers have unsuccessfully attempted to decode the book.

{{w|Dungeons and Dragons}} is a fantasy role-playing game with extremely detailed descriptions of fantastical worlds.

After being shown the Manuscript for the first time by Megan, Cueball argues that it should be obvious that it's just an ancient analogue of the Dungeons and Dragons rulebook, since the human tendency to invent fantastical worlds must have also existed in the past.

After concluding this, a shocked Cueball then asks in the title text how Megan got her hands on the original manuscript. Megan then suggests playing Druids and {{w|Dicotyledons}}, presumably the game defined by the manuscript.

Note that the use of the pronoun "your" in the last frame is anachronistic, as in early modern English it was only used as a plural pronoun; the proper pronoun would be "thine": "Thine Druid doth lose two points."

==Transcript==
:[Weird root vegetables surround a strange script.]

:[Megan holding up book.]
:Megan: This is the Voynich manuscript - a book, allegedly 500 years old, written in an unrecognized script. It's some kind of visual encyclopedia of imaginary plants and undeciphered "recipes".

:[Cueball opens the book.]
:Megan: It could be a hoax, a lost language, a cipher, an alien text, glossolatia - no one knows.
:Cueball: No one? But it's obvious.

:Megan: ...Obvious? Linguists and cryptographers have been stumped for decades.
:Cueball: They forget. Human nature doesn't change.

:Cueball: Just imagine someone found a book from our time, full of lists, illustrations, tables, and long, dry descriptions of nonexistent worlds written in an invented language. What have they found?
:Megan: ...Dear Lord. It ''is'' obvious.

:500 Years Earlier:
:[Three people are standing around pawns and a die. One is holding a sheet of paper, another is holding a book, the third is holding a scythe.]
:Person #1: Forsooth! I concoct an elixir of courage.
:Person #2: Nae! The source booke sayeth that requires some wolfsbane!
:Person #3: Your druid doth lose two points.

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]

1302: Year in Review

2013-12-11T14:41:47Z

Tenrek: Removed reference to aurora australis, as Megan explicitly states she was hoping to see the "northern lights."

{{comic
| number = 1302
| date = December 11, 2013
| title = Year in Review
| image = year_in_review.png
| titletext = All in all, I give this year a C-. There were no aurora visible from my house and that comet evaporated. They'd better not cancel the 2017 eclipse.
}}

==Explanation==
{{incomplete|Created by only one person}}

Many news organizations will review the entire year in late December (typically before the year has actually ended, so occasionally they are hit by a surprise afterwards). Cueball probably expects Megan to talk about the rollout of Obamacare, the death of Nelson Mandela, or various celebrity scandals; instead, Megan only cares about one thing: she never saw an {{w|aurora borealis}}, the dazzling natural geomagnetic light display.

The title text refers to {{w|Comet ISON}}. In February, a rough estimate of the comet's behavior predicted that it would become brighter than the full moon, a prediction that was widely reported by the media even though it was based on limited data and astronomers knew that it would not reach this brightness. In the end, although it was visible to the naked eye, it was never as bright as anybody hoped and apparently disintegrated in November (although a small core may remain).

The title text also refers to the {{w|2017 total eclipse}}, which will be visible (as a partial eclipse) for a few hours throughout North America on August 21 Monday, including a 100-mile band across the United States where it will be a total eclipse for a couple of minutes in the early afternoon. Although the weather may be cloudy, eclipses are highly predictable, so Megan is being extremely pessimistic to even suggest that it might not occur.

All in all, the comic suggests that the only events of significance to occur in any year are astronomical ones; the actions of humanity pale in comparison.

==Transcript==
{{incomplete transcript}}

:[Cueball, the TV host, introduces Megan, the reporter.]
:Cueball: We go live to our 2013: Year in Review!
:Megan: Thanks! In 2013, I didn't see an aurora.
:Cueball: I- what?

:Megan: The northern lights. I thought this would finally be the year. But it didn't happen.

:Cueball: Oh. Uh...what about the rest of the year?
:Megan: What do you mean?
:Cueball: Any big news stories?
:Megan: Oh yeah, tons.

:[Megan looks off screen to her left.]

:Cueball: ...Well, that was 2013: Year in Review.
:Megan: The sky's clearing up. I'll be outside.
:[Megan walks off camera.]

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]