explain xkcd - User contributions [en]

2605: Taylor Series

2022-04-12T10:50:52Z

Klaatubaradanikto: Add link to page of character Miss Lenhart

{{comic
| number = 2605
| date = April 11, 2022
| title = Taylor Series
| image = taylor_series.png
| titletext = The Taylor series should have been canceled after the first term.
}}

==Explanation==
{{incomplete|Created by THE MACLAURIN SERIES EVALUATED AT X PLUS EPSILON - Please change this comment when editing this page. Do NOT delete this tag too soon.}}

In mathematics, a {{w|Taylor series}} of a function is an approximation of the function in the form of an infinite sum of terms that are expressed as the function's {{w|Derivative|derivatives}}. Their expressions, usually referred to as "expansions," continue without end. Taylor series are useful for deriving numerical and {{w|Symbolic integration|symbolic}} forms of {{w|Irrational number|irrational}} values, {{w|Machin-like formula|such as π}}, to make them easier to integrate or otherwise manipulate with calculus.[https://www.mathsisfun.com/algebra/taylor-series.html] However, because they involve difficult calculus operations, and can be annoyingly tedious to {{w|Numerical analysis|calculate by hand}}, they are often not loved by math students.

[[Miss Lenhart]] appears to be teaching a class about how to use a Taylor series. She has explained what one is, and how it is used. She presumes her students want to keep learning about the series, in that they, "wish it would never end." She then says "Good news!" because the Taylor series does not end, each term being smaller than the last. The cartoon's humor is based on contrasting the idea of wishing the series will never end, which is ordinarily expressed regarding long-running sequences of enjoyable events, with the infinite nature of the Taylor series, which is probably not appreciated by her students struggling to understand why the sums {{w|Convergent series|converge}} to their resulting value.

The title text is a reference to the common practice among physicists and engineers of abbreviating the Taylor series to only the first few terms, typically one or two, in order to simplify the mathematics of their models. The title text is also a pun on the use of the word "series" to refer to a television program. It symbolizes the terms of the mathematical series as a {{w|metaphor}} with a television season, suggesting that only the first term is useful. It makes fun of the common sentiment against bad {{w|screenwriting}} of a series by saying that, "The series should have been cancelled after the first season," replacing "season" with "term."

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}

:[Miss Lenhart pointing a stick at a whiteboard, which has some scribbled text written on it and one line is circled.]
:Miss Lenhart: At this point, you're probably thinking, "I love this equation and wish it would never end!"
:Miss Lenhart: Well, good news!

:[Caption below the panel:]
:Taylor series expansion is the worst.

{{comic discussion}}

[[Category:Comics featuring Miss Lenhart]]
[[Category:Math]]

2228: Machine Learning Captcha

2019-11-14T11:41:37Z

Klaatubaradanikto:

{{comic
| number = 2228
| date = November 13, 2019
| title = Machine Learning Captcha
| image = machine_learning_captcha.png
| titletext = More likely: Click on all the pictures of people who appear disloyal to [name of company or government]
}}

==Explanation==
{{incomplete|Created by a HUMAN CAPTCHA. Which of the nine images would you click to prove you were human? A section about this. Also to explain what is actually on the pictures, which is not completely clear. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}
Many websites have difficulties with spambots, which are automated entities created in order to log onto a website and spam or otherwise wreak havoc upon it. To guard against this eventuality, websites have implemented {{w|CAPTCHA}}s, a challenge used to prove the user is a human and not an automated program. A typical CAPTCHA might distort a random sequence of letters and numbers and put it in a strange and/or mixed font and ask a user to type it, or it might show a set of pictures and ask the user which ones contain fire hydrants; these tasks are meant to be easy for humans but obscenely difficult for computers. [[:Category:CAPTCHA|CAPTCHAs]] are a recurring theme on xkcd.

CAPTCHAs run by Google are also used to train artificial intelligences to get better at these difficult tasks, such as reading poorly-scanned text or identifying objects of interest on the road (the latter being the subject of [[1897: Self Driving]]).

This comic jokes about malicious CAPTCHA which is being used to train an AI to dominate the world. In order to prevent people from taking shelter, the AI uses the CAPTCHA to ask humans to tell it places where they would hide. Then this AI would be ready to attack those locations in case someone hid there.

The title text imagines a different malicious CAPTCHA which Randall says is "more likely" than the robot-uprising scenario, in which a company or government asks users to identify "disloyal" members of society. Presumably the company or government would then train an AI to eliminate such "disloyal" members. This follows a theme of previous comic strips (e.g. [[1968: Robot Future]]) in which Randall expresses that he is more concerned about humans using AI for evil ends than he is about AI being evil in itself.

Note that while CAPTCHA in the title of this comic is written Captcha, not in the correctly all caps style, then on the xkcd page, [[Randall]] uses small caps, so although there is a distinction between capital and lower case letters, the word Captcha is actually written correctly out as C<small>APTCHA</small>!

==Transcript==
:[Cueball is sitting in an office chair at his desk with one hand in his lap and the other poised over the keyboard of his computer. A zigzag line is drawn from a starburst on the computer screen going above the computer to where it is shown what is displayed on the screen. At the top there is the following text:]
:Computer: To prove you're a human, click on all the photos that show places you would run for shelter during a robot uprising.

:[Below the text there are nine images arranged in a 3 by 3 square. In reading order they are: A house, possibly with an open carport; a large tree with two trees in the background; a bunker/bomb shelter; a car; a city skyline with several sky scrapers; a sidewalk with road on the left, grass on the right; a log with a board leaning up on the log; a mailbox; and a hole in the ground.]

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Artificial Intelligence]]
[[Category:Programming]]
[[Category:Robots]]
[[Category:CAPTCHA]]
[[Category:Politics]]

2228: Machine Learning Captcha

2019-11-14T11:39:44Z

Klaatubaradanikto: fixups of the explanation

{{comic
| number = 2228
| date = November 13, 2019
| title = Machine Learning Captcha
| image = machine_learning_captcha.png
| titletext = More likely: Click on all the pictures of people who appear disloyal to [name of company or government]
}}

==Explanation==
{{incomplete|Created by a HUMAN CAPTCHA. Which of the nine images would you click to prove you were human? A section about this. Also to explain what is actually on the pictures, which is not completely clear. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}
Many websites have difficulties with spambots, which are automated entities created in order to log onto a website and spam or otherwise wreak havoc upon it. To guard against this eventuality, websites have implemented {{w|CAPTCHA}}s, a challenge used to prove the user is a human and not an automated program. A typical CAPTCHA might distort a random sequence of letters and numbers and put it in a strange and/or mixed font and ask a user to type it, or it might show a set of pictures and ask the user which ones contain fire hydrants; these tasks are meant to be easy for humans but obscenely difficult for computers. [[:Category:CAPTCHA|CAPTCHAs]] are a recurring theme on xkcd.

CAPTCHAs run by Google are also used to train artificial intelligences to get better at these difficult tasks, such as reading poorly-scanned text or identifying objects of interest on the road (the latter being the subject of [[1897: Self Driving]]).

This comic jokes about malicious CAPTCHA which is being used to train an AI to dominate the world. In order to prevent people from taking shelter, the AI uses the CAPTCHA to ask humans to tell it places where they would hide. Then this AI would be ready to attack those locations in case someone hid there.

The title text imagines a different malicious CAPTCHA which Randall says is "more likely" than the robot-uprising scenario, in which a company or government asks users to identify "disloyal" members of society. Presumably the company or government would then train an AI to eliminate such "disloyal" members. This follows a theme of previous comic strips (e.g. [[1968: Robot Future]]) in which Randall expresses that he is more concerned about humans using AI for evil ends than he is about AI being evil in itself.

Note that while CAPTCHA in the title of this comic is written Captcha, not in the correctly all caps style, then on the xkcd page, [[Randall]] uses small caps, so although there is a distinction between capital and lower case letters, the word Captcha is actually written correctly out as C<small>APTCHA</small>!

==Transcript==
:[Cueball is sitting in an office chair at his desk with one hand in his lap and the other poised over the keyboard of his computer. A zigzag line is drawn from a starburst on the computer screen going above the computer to where it is shown what is displayed on the screen. At the top there is the following text:]
:Computer: To prove you're a human, click on all the photos that show places you would run for shelter during a robot uprising.

:[Below the text there are nine images arranged in a 3 by 3 square. In reading order they are: A house, possible with an open carport; a large tree with two threes in the background; a bunker/bomb shelter; a car; a city skyline with several sky scrapers; a sidewalk with road on the left, grass on the right; a log with a board leaning up on the log; a mailbox; and a hole in the ground.]

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Artificial Intelligence]]
[[Category:Programming]]
[[Category:Robots]]
[[Category:CAPTCHA]]
[[Category:Politics]]

1753: Thumb War

2016-11-02T08:35:45Z

Klaatubaradanikto:

{{comic
| number = 1753
| date = October 31, 2016
| title = Thumb War
| image = thumb_war.png
| titletext = "Seventeen, eighteen, nineteen, twenty--" / "Can't we just read Pat the Bunny?"
}}

==Explanation==
Two small children, one wearing a black hat, sitting among their toys are playing {{w|thumb war}}. This is a common game for children, in which two players hold hands and attempt to pin each other's thumb down. The game is often started with both players chanting "one, two three, four, I declare a thumb war." In some variations, the chant continues counting up by an additional set of four, with a rhyme. Once the opening chant is complete, the game consists of trying to pin the opponent's thumb down. A pinned thumb must be held down for long enough to complete a count of four, or to complete the closing chant, "one, two, three, four, I won the thumb war".

The standard concept is subverted here: The child that one day will turn into [[Black Hat]] interprets the simulation of hand-to-hand combat with thumbs differently, comparing it with real conflict. He shows this in further lines, invented by himself.

The second rhyme, "finger guns proliferate," is a pun on the {{w|finger gun}} gesture and describes {{w|Small arms trade|small arms proliferation}} - the spread of black-market weapons which often comes with war as captured and smuggled guns make their way into the hands of paramilitary groups. Black Hat transfers this into the "thumb war universe", introducing finger guns into the thumb-to-thumb combat.

The third rhyme continues the counting until twelve and mentions {{w|Digit (anatomy)|digits}} as in fingers, and states that they cannot protect themselves. This may be implying an imposition of {{w|Gun control|firearms regulation}} or {{w|arms control}} as a response to the small-arms proliferation in the previous verse, or the defenseless nature of noncombatants in war.

In the last line Black Hat states that, even though this thumb war goes on and on, the "thumb U.N.", the thumb war universe equivalent of the {{w|United Nations}} (UN), won't intervene. In real life the UN would try to put an end to a given war by using diplomatic power and has the mandate of using (blue-helmet) peace forces in war zones to put an end to violence and give out a mandate to nations so that they can intervene in some crisis on their own behalf.

The children thumb war game is in Black Hat's version instead a quite cynical portrayal of our world, criticizing the "might is right" mentality that is the sad reality of our globe, and the government of the world by the militarily strongest nations.

The other child, which will someday turn into [[Hairy]], meanwhile, is unnerved by all this and wants to stop playing. Since Hairy is just a normal child he is really not interested in Black Hat's realistic version of what a war really is.

In the title text it seems like Hairy interrupts Black Hat's last rhyme after twenty, and almost makes it a rhyme, as Bunny at least ends in the same letter. So it goes like this:
:Black Hat: Seventeen, eighteen, nineteen, twenty
:Hairy: Can't we just read Pat the Bunny?
Thus Hairy request that they to do something more appropriate for children like reading a picture book, specifically the "touch and feel" book for small children and babies known as {{w|Pat the Bunny}}.

This is the second time a young Black Hat has been used. The first was in [[1139: Rubber and Glue]]. Black Hat has continued to make Hairy uncomfortable even as an adult, for instance in [[1210: I'm So Random]].

==Transcript==
:[Two children are sitting on their knees between a toy truck to the left and five building blocks to the right; three square blocks are stacked in a precarious tower and to the right of the tower there is one more square block which has a rectangular block leaning on it. Both children have lots of hair but the child to the left has a black hat on, so they are possibly young versions of Black Hat and Hairy. They are sitting across from each other with one hand touching the other's hand. Their thumbs can be seen sticking up above their hands.]
:Black Hat: One, two, three, four, I declare a thumb war.
:Black Hat: Five, six, seven, eight, finger guns proliferate.
:Black Hat: Nine, ten, eleven, twelve, digits can't protect themselves.
:Black Hat: Thirteen, fourteen, fifteen, sixteen, thumb U.N. won't intervene.
:Hairy: I don't want to play with you anymore.

{{comic discussion}}

[[Category:Comics featuring Black Hat]]
[[Category:Comics featuring Hairy]]

1644: Stargazing

2016-02-17T08:14:12Z

Klaatubaradanikto: /* Explanation */

{{comic
| number = 1644
| date = February 17, 2016
| title = Stargazing
| image = stargazing.png
| titletext = Some of you may be thinking, 'But wait, isn't the brightest star in our sky the Sun?' I think that's a great question and you should totally ask it. On the infinite tree of possible conversations spread out before us, I think that's definitely the most promising branch.
}}

==Explanation==
{{incomplete|There may be another joke here}}
[[Megan]] is the host for a group of people who attend an evenings stargazing class. She is supposed to be a doctor or professor in {{w|astronomy}}, but it is already clear in the first panel that she is only acting, and she is clearly not very knowledgeable about astronomy, although she is clearly very interested in the objects that can bee seen in the night sky, i.e. in space.

It is later revealed that she had to look up the definition of "astronomer" in a dictionary, commenting on how boring a book that was. Since you are not meant to read a dictionary, but only look up individual words this suggest that Megan never used one of these before...

Although Megan thus certainly isn't an astronomer, and seems to only know superficial stuff about space, all of her statements are actually correct.

The title text mentions a typical comment (joke) that often comes up in discussions about which star is the brightest when seen from Earth. It is almost always clear from the context that the subject are stars in the night sky. But the joker is of course right as technically {{w|Sirius}} is not the brightest star in our sky, since the {{w|Sun}} is also a star. [[Randall]] is being sarcastic, and pointing out that being pedantic about this is a waste of everyone's time, considering all the other things they could talk about. He references the infinite tree of possible conversations they could have had, and "applaudes" the joker for choosing this promising branch, which will lead nowhere.

==Transcript==
{{incomplete transcript}}

{{comic discussion}}

[[Category:Comics featuring Megan]]
[[Category:Comics featuring Hairy]]
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Ponytail]]
[[Category:Multiple Cueballs]]