explain xkcd - User contributions [en]

2387: Blair Witch

2020-11-21T16:04:48Z

162.158.19.37: /* Explanation */ It wasn't all that common. Yes, it did happen occasionally, just like school shootings do happen today, but it is a stretch to call it "common"

{{comic
| number = 2387
| date = November 18, 2020
| title = Blair Witch
| image = blair_witch.png
| titletext = "Are you concerned the witches won't breed in captivity?" "Honestly, we're more concerned that they WILL. We don't know what it involves, but our biologists theorize that it's 'harrowing.'"
}}

==Explanation==
{{incomplete|Created by an INFANT BLAIR WITCH. Needs general cleanup/expansion..? Do NOT delete this tag too soon.}}

''{{w|The Blair Witch Project}}'' is a {{w|found footage (film technique)|found footage}} horror film released in 1999. For the marketing campaign of the film, the producers created the legend of the Blair Witch, a supernatural being whose legend originates in {{w|Burkittsville}}, MD. As it sometimes happened in Protestant societies in the {{w|colonial era}}, a woman was ostracized from the community after having been accused of {{w|witchcraft}}. This woman, who tends to conflict in name with various versions of the lore, would supposedly attempt to inflict revenge upon the community that exiled her, and these fearful people fled from the town.

The comic takes a humorous turn on the legend, suggesting a conservation program to save the Blair Witch. While the film was described by reliable sources as faked and misrepresented footage, the Blair Witch is postulated as separate species that is being tracked by the {{w|IUCN Red List}}. With the rise of camera-phones in the modern age, sightings of {{w|List of cryptids|beings that are most likely fictitious}} (such as Bigfoot and the Loch Ness Monster) are becoming rarer over time, due to [[1235: Settled|lack of credibility of a reported sighting without visual evidence]]. A species which has not been notably documented for a long time would indeed be moved to the "possibly {{w|extinct in the wild}}" category, as [[Megan]] notes.

In attempting to understand this in a way that does not involve refuting the existence of the Blair Witch, Megan cites {{w|habitat loss}} as the reason why encountering a Blair Witch might be more difficult. Habitat loss is in fact one of the most prominent and concerning reasons for extinction in recent years. Megan claims that suburban projects have fragmented the witch's "spooky forest" ecosystem, a reference to the many species that are dying off due to encroachment, logging, and similar human activities. Migration due to {{w|climate change}} is also an observable phenomenon in animal populations (and some plant populations, depending on their mode of travel while in seeds; those that rely on animals to germinate will migrate as well).

Megan then proposes a plan to catch and breed Blair Witches in an attempt to resurrect the species. This final panel is more obviously humorous, as even if the Blair Witch ''did'' exist separate from humans, there is only one,{{fact}} and thus any attempt to breed and repopulate would be futile. It may be possible that {{w|Parthenogenesis|this is not a problem}}, but if it is, it could also raise the objection that any pair of Blair Witch may both be female, and thus unable to reproduce. This could be resolved by (a) assuming that Witches can ({{w|Sequential hermaphroditism|sometimes?}}) be male as well, or (b) assuming that, much like Tremblay's salamander, where females can reproduce with a male of a related species (most likely human, in which case the project might have difficulty obtaining approval from an {{w|Institutional review board|ethics review board}}.) The phrase "Blair Witch Reintroduction Project" is a reference to ''The Blair Witch Project''.

The title-text suggests that the comic is a lecture, as Megan's whiteboard and pointer would suggest. A (presumed) student asks whether Megan is concerned that witches won't breed in captivity (a serious real-world concern to the IUCN). If this is a press conference, the question would be asked by a reporter instead. Megan replies that they are worried that there ''will'' be breeding, but biologists are unsure how the breeding occurs, calling it "harrowing" (presumably because they have captured the Blair Witch and it has set a curse on their laboratory as she supposedly did in Burkittsville). Historically, communities practicing witchcraft may have fled to the woods to engage in sometimes very sexual behaviors that others at the time were very frightened by.

==Transcript==
:[Megan is standing in front of a screen looking away from it at an audience off-panel. She is holding a stick, pointed at the chart behind her. The chart shows the stick figure from ''The Blair Witch Project''. Above is an unreadable line of text, and below are two smaller rectangles a smaller one above the other, the small seems to be empty, but there seems to be some kind of graph in the bottom one.]
:Megan: Other than the fake 1999 video, there have been no Blair Witch sightings in 30+ years.
:Megan: The IUCN redlist says the witch is "possibly extinct in the wild."

:[A close-up of Megan's face. The screen now shows a habitat map, with four separate shaded areas enclosed in a dotted line. The dotted line and one of the areas goes to the upper edge of the screen indicating they continue beyond the shown area. Beneath the dotted line and to the right there are three small squares, one of them clearly shaded the same way as the areas above. Next to each there is an unreadable label.]
:Megan: Development in the Maryland suburbs has fragmented the spooky forest habitat.
:Megan: Climate change will push any remnant populations north.

:[Back to the original setting, Megan is standing with the stick pointing downwards, and the chart is out of frame.]
:Megan: That's why we plan to capture any surviving witches and establish a breeding population.
:Megan: Then, in time, the Blair Witch Reintroduction Project can begin.

{{comic discussion}}

[[Category:Comics featuring Megan]]
[[Category:Fiction]]
[[Category:Biology]]

2335: Photo Deposit

2020-07-20T20:38:22Z

162.158.19.37: /* Explanation */

{{comic
| number = 2335
| date = July 20, 2020
| title = Photo Deposit
| image = photo_deposit.png
| titletext = It's okay, they scan the serial numbers and make sure you can't deposit the same bill more than once.
}}

==Explanation==
{{incomplete|Created by a BANKNOTE PHOTOCOPIER. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}
Some mobile banking apps allow users to deposit checks through the app. The comic parodies this by "depositing" cash via a mobile app. This leads to duplication of the money. Checks cannot be duplicated by this method, as a check is, in some ways, an instruction for one bank to send money to another.

The alt-text states that the app recognizes the serial numbers on the bills and prevents users from depositing them multiple times. It is unknown if multiple users can deposit the same bills. Even with a user being unable to deposit the same bills twice, they will still double the value of their cash, as they have a spendable copy of it in their account and they still have the original which could be spent outside the bank system.

In addition, the system would be highly vulnerable to counterfeiting. When depositing or paying with cash, the texture of cash is different from normal paper and therefore is a method to detect counterfeits. (In the U.S., bill are made from a sort of cloth. Other nations such as Canada and the U.K. have started introducing plastic banknotes.) In contrast, the low-resolution camera of a smartphone could be fooled by a printed image, or possibly even an image on a screen, effectively enabling an attacker to clone an arbitrary banknote without actually possessing it; resulting in a determined person to arbitrarily lower the purchasing power of existing money significantly, without issuing any new money.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
[Meghan is holding a (cash) bill in one hand, and is taking a picture of it with her smartphone with her other hand. Cueball is holding a (cash) bill in one hand, and is looking at his smartphone in his other hand.]
Cueball's phone: Deposit accepted!
Meghan's phone: click
[Caption below panel:]
After a lucrative six hours for us, our bank removed the new feature in their app that let you deposit cash by taking a picture of it.
{{comic discussion}}
[[Category:COVID-19]]

2335: Photo Deposit

2020-07-20T20:37:42Z

162.158.19.37: /* Explanation */

{{comic
| number = 2335
| date = July 20, 2020
| title = Photo Deposit
| image = photo_deposit.png
| titletext = It's okay, they scan the serial numbers and make sure you can't deposit the same bill more than once.
}}

==Explanation==
{{incomplete|Created by a BANKNOTE PHOTOCOPIER. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}
Some mobile banking apps allow users to deposit checks through the app. The comic parodies this by "depositing" cash via a mobile app. This leads to duplication of the money. Checks cannot be duplicated by this method, as a check is, in some ways, an instruction for one bank to send money to another.

The alt-text states that the app recognizes the serial numbers on the bills and prevents users from depositing them multiple times. It is unknown if multiple users can deposit the same bills. Even with a user being unable to deposit the same bills twice, they will still double the value of their cash, as they have a spendable copy of it in their account and they still have the original which could be spent outside the bank system.

In addition, the system would be highly vulnerable to counterfeiting. When depositing or paying with cash, the texture of cash is different from normal paper and therefore is a method to detect counterfeits. (In the U.S., bill are made from a sort of cloth. Other nations such as Canada and the U.K. have started introducing plastic banknotes.) In contrast, the low-resolution camera of a smartphone could be fooled by a printed image, or possibly even an image on a screen, effectively enabling an attacker to clone an arbitrary banknote without actually possessing it; resulting in a determined person to arbitrarily lower the purchasing power of existing money without issuing new money.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
[Meghan is holding a (cash) bill in one hand, and is taking a picture of it with her smartphone with her other hand. Cueball is holding a (cash) bill in one hand, and is looking at his smartphone in his other hand.]
Cueball's phone: Deposit accepted!
Meghan's phone: click
[Caption below panel:]
After a lucrative six hours for us, our bank removed the new feature in their app that let you deposit cash by taking a picture of it.
{{comic discussion}}
[[Category:COVID-19]]

2335: Photo Deposit

2020-07-20T20:36:02Z

162.158.19.37:

{{comic
| number = 2335
| date = July 20, 2020
| title = Photo Deposit
| image = photo_deposit.png
| titletext = It's okay, they scan the serial numbers and make sure you can't deposit the same bill more than once.
}}

==Explanation==
{{incomplete|Created by a BANKNOTE PHOTOCOPIER. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}
Some mobile banking apps allow users to deposit checks through the app. The comic parodies this by "depositing" cash via a mobile app. This leads to duplication of the money. Checks cannot be duplicated by this method, as a check is, in some ways, an instruction for one bank to send money to another.

The alt-text states that the app recognizes the serial numbers on the bills and prevents users from depositing them multiple times. It is unknown if multiple users can deposit the same bills. Even with a user being unable to deposit the same bills twice, they will still double the value of their cash, as they have a spendable copy of it in their account and they still have the original which could be spent outside the bank system.

In addition, the system would be highly vulnerable to counterfeiting. When depositing or paying with cash, the texture of cash is different from normal paper and therefore is a method to detect counterfeits. (In the U.S., bill are made from a sort of cloth. Other nations such as Canada and the U.K. have started introducing plastic banknotes.) In contrast, the low-resolution camera of a smartphone could be fooled by a printed image, or possibly even an image on a screen, effectively enabling an attacker to clone an arbitrary banknote without actually possessing it.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
[Meghan is holding a (cash) bill in one hand, and is taking a picture of it with her smartphone with her other hand. Cueball is holding a (cash) bill in one hand, and is looking at his smartphone in his other hand.]
Cueball's phone: Deposit accepted!
Meghan's phone: click
[Caption below panel:]
After a lucrative six hours for us, our bank removed the new feature in their app that let you deposit cash by taking a picture of it.
{{comic discussion}}
[[Category:COVID-19]]

2335: Photo Deposit

2020-07-20T20:34:58Z

162.158.19.37: /* Explanation */

{{comic
| number = 2335
| date = July 20, 2020
| title = Photo Deposit
| image = photo_deposit.png
| titletext = It's okay, they scan the serial numbers and make sure you can't deposit the same bill more than once.
}}

==Explanation==
{{incomplete|Created by a BANKNOTE PHOTOCOPIER. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}
Some mobile banking apps allow users to deposit checks through the app. The comic parodies this by "depositing" cash via a mobile app. This leads to duplication of the money. Checks cannot be duplicated by this method, as a check is, in some ways, an instruction for one bank to send money to another.

The alt-text states that the app recognizes the serial numbers on the bills and prevents users from depositing them multiple times. It is unknown if multiple users can deposit the same bills. Even with a user being unable to deposit the same bills twice, they will still double the value of their cash, as they have a spendable copy of it in their account and they still have the original which could be spent outside the bank system.

In addition, the system would be highly vulnerable to counterfeiting. When depositing or paying with cash, the texture of cash is different from normal paper and therefore is a method to detect counterfeits. (In the U.S., bill are made from a sort of cloth. Other nations such as Canada and the U.K. have started introducing plastic banknotes.) In contrast, the low-resolution camera of a smartphone could be fooled by a printed image, or possibly even an image on a screen, effectively enabling an attacker to clone an arbitrary banknote without actually possessing it.

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

{{comic discussion}}

2335: Photo Deposit

2020-07-20T20:33:24Z

162.158.19.37: /* Explanation */

{{comic
| number = 2335
| date = July 20, 2020
| title = Photo Deposit
| image = photo_deposit.png
| titletext = It's okay, they scan the serial numbers and make sure you can't deposit the same bill more than once.
}}

==Explanation==
{{incomplete|Created by a BANKNOTE PHOTOCOPIER. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}
Some mobile banking apps allow users to deposit checks through the app. The comic parodies this by "depositing" cash via a mobile app. This leads to duplication of the money. Checks cannot be duplicated by this method, as a check is, in some ways, an instruction for one bank to send money to another.

The alt-text states that the app recognizes the serial numbers on the bills and prevents users from depositing them multiple times. It is unknown if multiple users can deposit the same bills. Even with a user being unable to deposit the same bills twice, they will still double the value of their cash, as they have a spendable copy of it in their account and they still have the original which could be spent outside the bank system.

In addition, the system would be highly vulnerable to counterfeiting. When depositing or paying with cash, the texture of cash is different from normal paper and therefore is a method to detect counterfeits. (In the U.S., bill are made from a sort of cloth. Other nations such as Canada and the U.K. have started introducing plastic banknotes.) In contrast, the low-resolution camera of a smartphone could be fooled by a printed image, or possibly even an image on a screen.

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

{{comic discussion}}

2335: Photo Deposit

2020-07-20T20:32:42Z

162.158.19.37: /* Explanation */

{{comic
| number = 2335
| date = July 20, 2020
| title = Photo Deposit
| image = photo_deposit.png
| titletext = It's okay, they scan the serial numbers and make sure you can't deposit the same bill more than once.
}}

==Explanation==
{{incomplete|Created by a BANKNOTE PHOTOCOPIER. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}
Some mobile banking apps allow users to deposit checks through the app. The comic parodies this by "depositing" cash via a mobile app. This leads to duplication of the money. Checks cannot be duplicated by this method, as a check is, in some ways, an instruction for one bank to send money to another.

The alt-text states that the app recognizes the serial numbers on the bills and prevents users from depositing them multiple times. It is unknown if multiple users can deposit the same bills. Even with a user being unable to deposit the same bills twice, they will still double the value of their cash, as they have a spendable copy of it in their account and they still have the original which can be spent outside the bank system.

In addition, the system would be highly vulnerable to counterfeiting. When depositing or paying with cash, the texture of cash is different from normal paper and therefore is a method to detect counterfeits. (In the U.S., bill are made from a sort of cloth. Other nations such as Canada and the U.K. have started introducing plastic banknotes.) In contrast, the low-resolution camera of a smartphone could be fooled by a printed image, or possibly even an image on a screen.

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

{{comic discussion}}

Talk:2309: X

2020-05-23T16:41:01Z

162.158.19.37: better examples for the math-related section; also fixed a typo in one of the images linked above

id certainly use that language lol ([[User talk:172.69.70.101|172.69.70.101]])

-- haXkell is a X-based dialect of haskell 
X :: Integer -> Integer 
X 0 = 1 
X X = X * X (X-1) 
[[User:Capncanuck|Capncanuck]] ([[User talk:Capncanuck|talk]]) 02:35, 21 May 2020 (UTC)

https://esolangs.org/wiki/X isn't taken. --[[User:Blacksilver|Blacksilver]] ([[User talk:Blacksilver|talk]]) 02:40, 21 May 2020 (UTC)

Some unique looking variable names would be X and x in the fonts Webdings, Wingdings, Wingdings 2, and Wingdings 3. 
They are respectively as follows: 
X
x
X
x
X
x
X
x --[[User:Dstrube|Dstrube]] ([[User talk:Dstrube|talk]]) 02:49, 21 May 2020 (UTC) 
:This comment is quite uninformative to someone who doesn't have those fonts installed. [[User:Angel|Angel]] ([[User talk:Angel|talk]]) 09:57, 21 May 2020 (UTC)
:: This comment highlights another issue with Cueball's language. [[User:Mikemk|Mikemk]] ([[User talk:Mikemk|talk]]) 11:22, 21 May 2020 (UTC)

As well as esolangs, among which I would consider the likes of Whitespace and b****fuck as potential inspirations, I think I'm also minded of TempleOS and its creator as vaguer but possibly still related influences... [[Special:Contributions/162.158.158.163|162.158.158.163]] 03:28, 21 May 2020 (UTC)
:I find it ironic that you censored the word "brain" but left in the word "fuck".
:[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 16:09, 21 May 2020 (UTC)

I added an explanation of what a variable is and why it's bad to have every one named X. It's pretty rudimentary though, hope someone more experienced than me will improve it. [[User:Unpopular Opinions|Goodbye, world!]] ([[User talk:Unpopular Opinions|talk]]) 04:39, 21 May 2020 (UTC)

:Forth basically doesn't use variable names. Commands operate on and consume the last number mentioned. A Forth program "1 2 3 . . ." prints 3, then 2, then 1. "2 3 + ." prints 5 I think??
:In Microsoft "Transact-SQL" you can script variables named starting @ and temporary objects starting #. I promise I try to resist naming objects @ or # and especially if @ or # is going to be a different object in each program... or is not. And if someone else needs to reads this (and I don't want to punish them). Not to mention "@ " for instance. Robert Carnegie rja.carnegie@gmail.com [[Special:Contributions/141.101.98.54|141.101.98.54]] 09:21, 21 May 2020 (UTC)

Psh you're all chicken. Chicken chicken chicken.

[[https://media.discordapp.net/attachments/677507038607048704/706860858587873310/ShapeLikeItSelf_img1.png Language where you can have return keyword in a if condition]],
[[https://media.discordapp.net/attachments/677507038607048704/713791559371456652/unknown.png Language that uses unicode symbols for built_in operators]],
[[https://media.discordapp.net/attachments/677507038607048704/712915431446282240/unknown.png Language, I have no words to describe]],
and this this '''X''' thing is winning so far...
[[Special:Contributions/162.158.89.139|162.158.89.139]] 06:35, 21 May 2020 (UTC)

:Yeah, but C++ does that shit either '''unintentionally''' or '''at user demand''' (although, to be clear, I'm not saying it's any good; C++ and Java are possibly the worst programming languages in terms of shoddy design). The X programming language is just the designer being an asshole. [[Special:Contributions/172.68.189.205|172.68.189.205]] 07:04, 21 May 2020 (UTC)
::Those links have nothing to do with C++/Java and you can Not do those things in C++ or Java (except an if in an assignment).[[Special:Contributions/162.158.92.208|162.158.92.208]] 08:02, 21 May 2020 (UTC)
:Those look like pretty sane language features; just looks weird because of the Eliza effect; those keywords don't behave like you'd expect them to based on experience of other languages. In the first example, you can certainly do that in Perl using "if (defined wantarray)"; it's just unusual (but comprehensible) to name the keyword "return". What language is that? [[User:Angel|Angel]] ([[User talk:Angel|talk]]) 09:57, 21 May 2020 (UTC)
::Language is called ShapedLikeItSelf, but it currently has no runner. Documentation is just of images like these on discord server.
::[[https://discord.gg/ercPss9 This is link to it]] if you are intersted. [[Special:Contributions/162.158.89.19|162.158.89.19]] 10:19, 21 May 2020 (UTC)

Did Randall refer to this comic? https://xkcd.com/1537/
I vaguely remember another one about an esoteric language. Is there a category of programming languages on explainxkcd?

Am I the only one that tried fiddling the CSS on the page to see if the X would change? Spoiler -> It didn't. [[User:Xseo|Xseo]] ([[User talk:Xseo|talk]]) 08:54, 21 May 2020 (UTC)

If X is the only variable name, can it be omitted? For example, writing a single-argument function name in a different font to imply which X should be treated as its argument. And that gets me wondering how the source is stored; will the IDE allow use of fonts not installed on your system? Will the compiler fail if it can't find the font, requiring you to track down all of the fonts a developer used in order to compile their code? And what would be the legality of mixing open-source code and proprietary fonts? [[User:Angel|Angel]] ([[User talk:Angel|talk]]) 09:57, 21 May 2020 (UTC)

"… and array indices start at 8, because anything smaller than that would be unreadable." [[User:Angel|Angel]] ([[User talk:Angel|talk]]) 10:00, 21 May 2020 (UTC)

Who is going to implement this first??[[Special:Contributions/108.162.216.122|108.162.216.122]] 13:03, 21 May 2020 (UTC)

Hey guys what coding language did he do to almost be arrested? [[Special:Contributions/162.158.187.139|162.158.187.139]] 14:18, 21 May 2020 (UTC)Anonymous
:Well, I've got this one with just four operands, everything's a relative address in 4-cored circular memory and there's no paractical differentiation between the packed opcodes, addresses and data (or their 2-bit lower-limit boundaries) when operated upon from elsewhere. Everything suggests it should be be Turing-complete. [[Special:Contributions/162.158.155.242|162.158.155.242]] 11:47, 22 May 2020 (UTC)

Isn't the fixed vs variable width a pun on the variable's internal size, eg. a 64-bit integer [fixed width) vs a string (variable width) ?

I sure hope this new language at least supports indexed tuples. If so, that wouldn't be so bad, unless for some reason I needed more than one tuple in the same scope.[[User:Whiteheadw|Whiteheadw]] ([[User talk:Whiteheadw|talk]]) 23:01, 21 May 2020 (UTC)

Harrumph. I'm sticking with LOLcode http://www.lolcode.org/ and thats an end of it. [[User:Cellocgw|Cellocgw]] ([[User talk:Cellocgw|talk]]) 14:03, 22 May 2020 (UTC)

Is this a continuation of the [[:Category:Code Quality|Code Quality]] series? [[User:TomW1605|TomW1605]] ([[User talk:TomW1605|talk]]) 14:05, 22 May 2020 (UTC)

I'm not sure that this: "ℝ denotes the set of natural numbers, and is distinct from R" is strictly true. The way I was taught is that boldfaced R does stand for the real numbers, except when it doesn't, and blackboard-bold ℝ (and Q, and C, and Z) are just what you write on the blackboard since it's impossible to make a clear boldfaced R with chalk.
Not that the main point doesn't stand--too many circumstances where plain P, bold P, italic P, and fancy curly script P all mean different things. [[Special:Contributions/162.158.62.105|162.158.62.105]] 18:57, 22 May 2020 (UTC)

: Blackboard Bold isn't a reliable convention but, generally, '''N''' is the set of naturals, '''R''' reals. https://en.m.wikipedia.org/wiki/Blackboard_bold [[Special:Contributions/172.68.143.30|172.68.143.30]] 20:32, 22 May 2020 (UTC)

And to continue on the "jab at mathematicians" line of thought... Either the recently mentioned P's or an "a vs alpha" (a in the Symbol font) or something similar might make better examples than that '''N''' in [[#Explanation]]... -- [[Special:Contributions/162.158.19.37|162.158.19.37]] 16:41, 23 May 2020 (UTC)

2117: Differentiation and Integration

2020-02-28T05:43:53Z

162.158.19.37: /* Differentiation */

{{comic
| number = 2117
| date = February 27, 2019
| title = Differentiation and Integration
| image = differentiation_and_integration.png
| titletext = "Symbolic integration" is when you theatrically go through the motions of finding integrals, but the actual result you get doesn't matter because it's purely symbolic.
}}

==Explanation==
This comic illustrates the old saying [https://mathoverflow.net/q/66377 "Differentiation is mechanics, integration is art."] It does so by providing a {{w|flowchart}} purporting to show the process of differentiation, and another for integration.

{{w|Derivative|Differentiation}} and {{w|Antiderivative|Integration}} are two major components of {{w|calculus}}. As many Calculus 2 students are painfully aware, integration is much more complicated than the differentiation it undoes.

However, Randall dramatically overstates this point here. After the first step of integration, Randall assumes that any integration can not be solved so simply, and then dives into a step named "????", suggesting that it is unknowable how to proceed. The rest of the flowchart is (we can assume deliberately) even harder to follow, and does not reach a conclusion. This is in contrast to the simple, straightforward flowchart for differentiation. The fact that the arrows in the bottom of the integration part leads to nowhere indicates that "Phone calls to mathematicians", "Oh no" and "Burn the evidence" are not final steps in the difficult journey. The flowchart could be extended by Randall to God-knows-where extents.

It should be noted that Randall slightly undermines his point by providing four different methods, and an "etc", and a "No"-branch for attempting differentiation with no guidelines for selecting between them.

===Differentiation===
'''{{w|Chain rule}}'''

For any <math> \frac{d}{dx}f(x)=f'(x)</math> and <math> \frac{d}{dx}g(x)=g'(x) </math>, it follows that <math> \frac{d}{dx}(f(g(x)))=f'(g(x))\cdot g'(x)</math>.

'''{{w|Power Rule}}'''

For any <math> f(x)=g(x)^a </math> and <math> \frac{d}{dx}g(x)=g'(x) </math>, it follows that <math> \frac{d}{dx}f(x)=a\cdot g(x)^{a-1}\cdot g'(x) </math>.

'''{{w|Quotient rule}}'''

For any <math> \frac{d}{dx}f(x)=f'(x)</math> and <math> \frac{d}{dx}g(x)=g'(x) </math>, it follows that <math> \frac{d}{dx} \frac{f(x)}{g(x)}=\frac{f'(x)\cdot g(x)-f(x)\cdot g'(x)}{(g(x))^2}</math> if <math>g(x)\ne 0</math>.

'''{{w|Product rule}}'''

For any <math> \frac{d}{dx}f(x)=f'(x)</math> and <math> \frac{d}{dx}g(x)=g'(x) </math>, it follows that <math> \frac{d}{dx}(f(x)\cdot g(x))=f'(x)\cdot g(x)+f(x)\cdot g'(x)</math>.

===Integration===
'''{{w|Integration by parts}}'''

The "product rule" run backwards. Since <math>(uv)' = uv' + u'v</math>, it follows that by integrating both sides you get <math> uv = \int u dv + \int v du</math>, which is more commonly written as <math>\int u dv = uv - \int v du</math>. By finding appropriate values for functions <math>u, v</math> such that your problem is in the form <math>\int u dv</math>, your problem ''may'' be simplified. The catch is, there exists no algorithm for determining what functions they might possibly be, so this approach quickly devolves into a guessing game - this has been the topic of an earlier comic, [[1201: Integration by Parts]].

'''{{w|Integration by substitution|Substitution}}'''

The "chain rule" run backwards. Since <math> d(f(u)) = (df(u))du</math>, it follows that <math>f(u) = \int df(u) du</math>. By finding appropriate values for functions <math>f, u</math> such that your problem is in the form <math>\int df(u) du</math> your problem ''may'' be simplified.

'''{{w|Cauchy's integral formula|Cauchy's Formula}}'''

Cauchy's Integral formula is a result in complex analysis that relates the value of a contour integral in the complex plane to properties of the singularities in the interior of the contour. It is often used to compute integrals on the real line by extending the path of the integral from the real line into the complex plane to apply the formula, then proving that the integral from the parts of the contour not on the real line has value zero.

'''{{w|Partial_fraction_decomposition#Application_to_symbolic_integration|Partial Fractions}}'''

Partial fractions is a technique for breaking up a function that comprises one polynomial divided by another into a sum of functions comprising constants over the factors of the original denominator, which can easily be integrated into logarithms.

'''Install {{w|Mathematica}}'''

Mathematica is a modern technical computing system spanning most areas. One of its features is to compute mathematical functions. This step in the flowchart is to install and use Mathematica to do the integration for you. Here is a description about the [https://reference.wolfram.com/language/tutorial/IntegralsThatCanAndCannotBeDone.html intricacies of integration and how Mathematica handles those]. (It would be quicker to try [https://www.wolframalpha.com Wolfram Alpha] instead of installing Mathematica, which uses the same backend for mathematical calculations.)

'''{{w|Riemann integral|Riemann Integration}}'''

The Riemann integral is a definition of definite integration. <math>\sum_{i=0}^{n-1} f(t_i) \left(x_{i+1}-x_i\right).</math> Elementary textbooks on calculus sometimes present finding a definite integral as a process of approximating an area by strips of equal width and then taking the limit as the strips become narrower. Riemann integration removes the requirement that the strips have equal width, and so is a more flexible definition. However there are still many functions for which the Riemann integral doesn't converge, and consideration of these functions leads to the {{w|Lebesgue integration|Lebesgue integral}}. Riemann integration is not a method of calculus appropriate for finding the anti-derivative of an elementary function.

'''{{w|Stokes' Theorem}}'''

Stokes' theorem is a statement about the integration of differential forms on manifolds. <math>\int_{\partial \Omega}\omega=\int_\Omega d\omega\,.</math> It is invoked in science and engineering during control volume analysis (that is, to track the rate of change of a quantity within a control volume, it suffices to track the fluxes in and out of the control volume boundary), but is rarely used directly (and even when it is used directly, the functions that are most frequently used in science and engineering are well-behaved, like sinusoids and polynomials).

'''{{w|Risch Algorithm}}'''

The Risch algorithm is a notoriously complex procedure that, given a certain class of symbolic integrand, either finds a symbolic integral or proves that no elementary integral exists. (Technically it is only a semi-algorithm, and cannot produce an answer unless it can determine if a certain symbolic expression is {{w|Constant problem|equal to 0}} or not.) Many computer algebra systems have chosen to implement only the simpler Risch-Norman algorithm, which does not come with the same guarantee. A series of extensions to the Risch algorithm extend the class of allowable functions to include (at least) the error function and the logarithmic integral. A human would have to be pretty desperate to attempt this (presumably) by hand.

'''{{w|Bessel function}}'''

Bessel functions are the solution to the differential equation <math> x^2 \frac{dy^2}{dx^2}+x \frac{dy}{dx}+(x^2-n^2)*y=0</math>, where n is the order of Bessel function. Though they do show up in some engineering, physics, and abstract mathematics, in lower levels of calculus they are often a sign that the integration was not set up properly before someone put them into a symbolic algebra solver.

'''Phone calls to mathematicians'''

This step would indicate that the flowchart user, desperate from failed attempts to solve the problem, contacts some more skilled mathematicians by phone, and presumably asks them for help. The connected steps of "Oh no" and "Burn the evidence" may suggest the possibility that this interaction might not play out very well and could even get the caller in trouble.
Specialists and renowned experts being bothered - not to their amusement - by strangers, often at highly inconvenient times or locations, is a common comedic trope, also previously utilized by xkcd (for example in [[163: Donald Knuth]]).

'''Burn the evidence'''

This phrase parodies a common trope in detective fiction, where characters burn notes, receipts, passports, etc. to maintain secrecy. This may refer to the burning of one's work to avoid the shame of being associated with such a badly failed attempt to solve the given integration problem. Alternatively, it could be an ironic hint to the fact that in order to find the integral, it may even be necessary to break the law or upset higher powers, so that the negative consequences of a persecution can only be avoided by destroying the evidence.

'''{{w|Symbolic integration}}'''

Symbolic algebra is the basic process of finding an antiderivative function (defined with symbols), as opposed to numerically integrating a function. The title text is a pun that defines the term not as integration that works with symbols, but rather as integration as a symbolic act, as if it were a component of a ritual. A symbolic act in a ritual is an act meant to evoke something else, such as burning a wooden figurine of a person to represent one’s hatred of that person. Alternatively, the reference could be seen as a joke that integration might as well be a symbol, like in a novel, because Randall can't get any meaningful results from his analysis.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:[Two flow charts are shown.]

:[The first flow chart has four steps in simple order, one with multiple recommendations.]
:DIFFERENTIATION
:Start
:Try applying
::Chain Rule
::Power Rule
::Quotient Rule
::Product Rule
::Etc.
:Done?
::No [Arrow returns to "Try applying" step.]
::Yes
:Done!

[The second flow chart begins like the first, then descends into chaos.]
:INTEGRATION
:Start
:Try applying
::Integration by Parts
::Substitution
:Done?
:Haha, Nope!

:[Chaos, Roughly from left to right, top to bottom, direction arrows not included.]
::Cauchy's Formula
::????
::???!?
::???
::???
::?
::Partial Fractions
::??
::?
::Install Mathematica
::?
::Riemann Integration
::Stokes' Theorem
::???
::?
::Risch Algorithm
::???
::[Sad face.]
::?????
::???
::What the heck is a Bessel Function??
::Phone calls to mathematicians
::Oh No
::Burn the Evidence
::[More arrows pointing out of the image to suggest more steps.]

{{comic discussion}}
[[Category:Analysis]]
[[Category:Flowcharts]]

959: Caroling

2020-02-06T11:51:25Z

162.158.19.37: /* Explanation */

{{comic
| number = 959
| date = October 3, 2011
| title = Caroling
| image = caroling.png
| titletext = For a thousand generations we vowed never to forget how his soldiers feasted on our brother Stephen.
}}

==Explanation==
Here are the lyrics for the first verse of the Christmas Carol, "{{w|Good King Wenceslas}}"

:''Good King Wenceslas looked out, on the Feast of Stephen,''
:''When the snow lay round about, deep and crisp and even;''
:''Brightly shone the moon that night, tho' the frost was cruel,''
:''When a poor man came in sight, gath'ring winter fuel.''

While not a king, {{w|Wenceslaus I, Duke of Bohemia}} is considered a martyr and a saint. Far from being responsible for any massacre, he protected his subjects from external dominance and is still a national hero to the Czech people. [[Black Hat]] is supplying {{w|disinformation}} to unsuspecting carolers, either to shut them up, by making them falsely think that they are associating themselves with a morally reprehensible man, or just because he's a [[classhole]] like that.

The title text references "the {{w|St. Stephen's Day|Feast of Stephen}}" which is also known as the "Feast of St. Stephen" or "St. Stephen's Day", which is a holiday celebrated on 26 or 27 December (which is 9 January in of the {{w|Gregorian calendar}}), depending on the Western or Eastern church respectively. It is not actually a feast that involved eating a person named Stephen.{{Citation needed}}
If you look closely, you can see that the carolers may be a family. The man and woman are confused by what Black Hat has said, and the girl is looking to the adults, perhaps gauging their facial reactions, or just waiting for their reply.

==Transcript==
:[Three people, two the same size, one smaller stand together singing Christmas carols.]
:Carolers (in unison): Good king Wenceslas looked out on the—

:[Black Hat leans out of an above ground window.]
:Black Hat: King Wenceslas massacred my people.

:[The carolers stand in silence, the smaller one looks at the others.]

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

955: Neutrinos

2020-02-06T10:56:30Z

162.158.19.37: /* Explanation */

{{comic
| number = 955
| date = September 23, 2011
| title = Neutrinos
| image = neutrinos.png
| titletext = I can't speak to the paper's scientific merits, but it's really cool how on page 10 you can see that their reference GPS beacon is sensitive enough to pick up continential drift under the detector (interrupted halfway through by an earthquake).
}}

==Explanation==
The "{{w|Faster-than-light neutrino anomaly|Neutrino speed of light thing}}" mentioned in this comic [http://news.cnet.com/8301-30685_3-20110594-264/physics-shocker-neutrinos-clocked-faster-than-light/ was an actual story] from the day before the comic was posted. An experiment at {{w|CERN}} caused a stream of neutrinos to be passed from CERN in Switzerland to a receiving station at the INFN laboratories of Gran Sasso in Italy ({{w|LNGS}}). The initial findings from the experiment were that the neutrinos arrived at the detector in less time than a beam of light would have taken. The neutrinos had apparently exceeded the {{w|speed of light}}.

{{w|Albert Einstein}} famously posited that the speed of light in a vacuum is both constant and absolutely the fastest possible speed for any object in the universe. Nothing can accelerate to any faster speed. Therefore, a report that neutrinos have been found travelling faster than light challenges a fundamental law of physics and turns all of physics, or at least {{w|special relativity}}, on its head.

Prior experience has shown [[Cueball]] that in such cases, [[386|arguing with people]] and preaching caution is futile and will lead to "pointless arguments about Galileo". {{w|Galileo Galilei}} was famously convicted of heresy for his defending the {{w|Heliocentrism|heliocentric system}}, and is often used as an example of revolutionary ideas being suppressed by the powerful. Believers in the new findings would thus accuse Cueball and the scientific community of being as stubborn and oppressive as the Inquisition in Galileo's time, and even compare them to the {{w|Thought Police}} from George Orwell's ''{{w|Nineteen Eighty-Four|1984}},'' another popular archetype of oppressive measures.

Cueball realizes that it is more satisfying and profitable to place bets with them instead. His reasoning is that almost invariably, these supposedly world-changing discoveries end up falling apart after further investigation, and that if it doesn't, then the discovery itself will satisfy his scientific curiosity enough to outweigh his monetary loss. This is similar to {{w|Stephen Hawking}}'s {{w|scientific wager}}s, where Hawking set bets such that, if he was wrong, he would be paid, and if he was right, he'd have to pay and wouldn't mind because he'd just have been proven right.

The title text is a reference to a graph published similar to, if not the same as, the one found [http://indianysn.files.wordpress.com/2011/10/cern-opera-graph.jpg here]. The continental drift can be seen, as well as the clearly marked jump showing the earthquake in question.

Postscript: Cueball (that is, Randall) was correct. The experiment was found to be flawed. [http://www.redorbit.com/news/science/1112551696/cern-confirms-neutrinos-not-faster-than-light/ Neutrinos are not faster than light],{{Citation needed}} the data was probably wrong due to a faulty connection on an optical fiber.

==Transcript==
:[Megan and Cueball are talking.]
:Megan: Did you see the neutrino speed of light thing?
:Cueball: Yup! Good news; I need the cash.
:Megan: Huh? Cash?

:[Text above half-sized panel.]
:Yeah. When there's a news story about a study overturning all of physics, I used to urge caution, remind people that experts aren't all stupid, and end up in pointless arguments about Galileo.

:[Half-height panel.]
:[Cueball sitting on chair, looking down at laptop in his lap. Books and things are on a desk in front of him.]
:Cueball: No, this isn't ''about'' whether relativity exists. If it didn't, your GPS wouldn't work.
:Cueball: What do you mean, "science thought police"? Have you seen our budget? We couldn't ''begin'' to afford our own thought police.

:[Megan and Cueball talking again.]
:Megan: That sounds miserable and unfulfilling.
:Cueball: Yup. So I gave up, and now I just find excited believers and bet them $200 each that the new result won't pan out.

:[Same as last panel.]
:Megan: That's mean.
:Cueball: It provides a good income, and if I'm ever wrong, I'll be too excited about the new physics to notice the loss.

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

2251: Alignment Chart Alignment Chart

2020-01-08T21:49:24Z

162.158.19.37: /* Explanation */

{{comic
| number = 2251
| date = January 6, 2020
| title = Alignment Chart Alignment Chart
| image = alignment_chart_alignment_chart.png
| titletext = I would describe my personal alignment as "lawful heterozygous silty liquid."
}}

==Explanation==
{{incomplete|Created by a [[User:DgbrtBOT|TRUE NEUTRAL BOT template]]. Needs explanations of each alignment chart, and probably some editing for clarity.}}

"Alignment" and "alignment charts" come from tabletop roleplaying games, most prominently ''{{w|Dungeons & Dragons}}''. Every character has an {{w|Alignment (Dungeons & Dragons)|alignment}}, which very roughly identifies their tendencies. The most widely used alignment system was introduced in the ''{{w|Dungeons & Dragons Basic Set}}'' in 1977 and has been reused in many (but not all) subsequent editions of the game. This system uses two perpendicular axes, each divided into three levels (for a total of nine categories). The two axes are:
* Lawful/neutral/chaotic: this axis says whether a character is strongly devoted to, indifferent about, or categorically opposed to following established rules.
* Good/neutral/evil: this axis says whether a character is generally inclined to commit good deeds or evil deeds.

In this system, the "lawful" attribute is independent from the "good" attribute. Lawful alignment means that a character is committed to a set of rules, which can refer to actual established laws, or to something like a rigid personal code, a set of traditions, or a chain of command, while a chaotic alignment means that a character has no interest in those, and may actively oppose them. The good vs evil scale is generally based on a character's concern for the lives and well-being of others, a good character will actively seek to help others and prevent harm, while an evil character will have no such concern and may actively harm others. Being 'good' is assumed to be independent of being 'lawful'. For example, a character who actively breaks laws to help those who are unjustly imprisoned or oppressed would be be considered to be "chaotic good". In both cases, a neutral alignment can indicate a character's indifference to a concept, or that their commitment is conditional, or that they consciously seek to balance both sides. A character with the "neutral neutral" alignment is called a true neutral.

An alignment chart is a grid that divides the alignments, usually for the purpose of putting descriptions or particular characters on it. Alignment charts are frequently used as a [https://knowyourmeme.com/memes/mcdonalds-alignment-chart meme template], where humorous or absurdist things are organized into different alignments. In addition to the "classic" Dungeons and Dragons alignment chart, there are a number of variant alignment charts in use as meme templates. Many keep the three-by-three grid structure but replace the lawful-neutral-chaotic and good-neutral-evil axes with descriptions.

This comic claims to be a meta-alignment chart, where nine "alignment charts" are themselves sorted into the nine Dungeons and Dragons alignments, following the use of alignment charts to humorously classify abstract concepts. However, these "alignment charts" are mostly diagrams used in academic classifications, which are being treated as if they were blank meme templates. There are two levels of absurdity here: first, the idea of using these diagrams to classify things they were never intended for, and second, the conflation of chaos as a physics concept and an assigned moral weights as it applies to each of these classification systems.

The title text describes Randall's alignment as "lawful heterozygous silty liquid" which references the true neutral, neutral good, lawful good, and lawful neutral charts in the Alignment Chart Alignment Chart. Lawful is the left side of an alignment chart, heterozygous is the top right or bottom left of a Punnet Square, silty is the bottom right of a soil chart, and liquid is the top right of a phase diagram. As such, the title test describes Randall's alignment as between Lawful Neutral and Neutral Good on this chart.

{| class="wikitable"
!Alignment
!Chart
!Explanation
|-
|Lawful Good
|{{w|Soil texture|Soil chart}}
|This chart shows the USDA classification of soil types by their relative proportions of sand, clay and silt. The chart is a ternary diagram (very common in geology), so soils with more clay plot towards the upper corner, soils with more sand to the bottom left, and soils with more silt to the bottom right. This chart has been used humorously as an alignment chart ([https://www.reddit.com/r/PrequelMemes/comments/8wakd4/anakin_soil_reference_chart/ for example]) and may have been the inspiration for Randall to use scientific diagrams as alignment charts. In addition to being Lawful Good, this grid cell is also the upper left cell of the chart and will be read first, making it a good place to put this chart as a "jumping off point". [https://what-if.xkcd.com/83/ What If 83 "Star Sand"] cites Randall as "...very satisfied with this chart, it's like the erosion geology edition of the electromagnetic spectrum chart..."
|-
|Neutral Good
|{{w|Punnett square}}
| Punnet squares are a visual method of determining what traits an organism might have based on the traits of the organism's parents. It relies on the principle that a trait is either dominant (indicated with capital letters) or recessive (indicated with lowercase letters). The exact combination of dominant or recessive genes that a child organism receives from their parents determines their traits. Heterozygous and homozygous refers to the pairs of alleles in an organism’s genotype, indicating mixed or same alleles, respectively. Randall later uses "heterozygous" in the title text. Note that it is possible for a phenotype to be expressed the same between some heterozygotes and homozygotes, e.g., persons with genotypes heterozygous "Aa" and homozygous "AA" will both express blood type A.
Therefore, the Punnett Square is a good chart because it is both a simple and true geometric predictor of inheritance, but it tends to be neutral because of complicating factors such as polygenic inheritance; these and other factors will cause genotypic frequency to deviate from expected 1:2:1 patterns.
|
|-
|Chaotic Good
|{{w|IPA vowel chart with audio|IPA vowel chart }}
|This chart shows the relationship between different vowels according to the {{w|International Phonetic Alphabet}}. The position of the vowel on the chart serves roughly as an indicator of the position of the tongue in the mouth of the speaker. As different vowel sounds are created by changes in different parts of the mouth, including lip roundness which is expressed in the chart implicitly as an invisible third dimension, vowel identification is qualitative and often up to interpretation, and vowel expression can change dramatically from region to region or even person to person within the same language, the categories described by the chart might be considered chaotic. The chart is missing the near-open central vowel ⟨ɐ⟩.
|-
|Lawful Neutral
|{{w|Phase diagram}}
|A phase diagram shows the equilibrium phases of matter present for a particular temperature, pressure, and composition. The diagram included is a unary phase diagram of a typical material that has a solid, liquid, and gas phase depending on the temperature and pressure for a fixed composition. Phase diagrams are useful for understanding how a material may change as its conditions change. For example, the air pressure of Mars is such that there is no temperature at which liquid water can exist in equilibrium on its surface. Water exists as ice until the temperature reaches a point where it sublimates directly into steam.

This phase diagram does not specify what material is depicted, but it is certainly ''not'' the phase diagram of water. On this diagram, compressing the liquid phase will transform the material into a solid, which is how most materials behave, but the solid/liquid phase line for water tilts the opposite direction. This is why water ice floats on liquid water, for example.

Phase diagrams follow the laws of thermodynamics and concern themselves with the order in which things ''should'' be, so they are inherently lawful.
|-
|True Neutral
|Alignment chart
|All alignment charts are neutral unless humans contaminate them.
|-
|Chaotic Neutral
|CIE chromaticity diagram
|The {{w|chromaticity}} diagram is a chart of colors. Visible colors form a shape like a triangle with two bulging sides in the diagram. The curved line within the diagram shows the chromaticities of {{w|Black body|black bodies}} over a range of color temperatures. The chromaticity diagram shows colors independent of luminance.
The chart is not a simple geometric shape, so it is labeled as chaotic. Points on the diagram can be specified as combinations of three underlying iluminants (the colors of which may not all be visible). It can also be described in polar form with angle and radial distance from some central point, where the maximum radial distance depends on the angle.
The fact that the colors may not show properly on a screen, making the diagram incorrect, may also contribute to its chaotic aspect.
|
|-
|Lawful Evil
|Political compass
|[https://www.politicalcompass.org/ Political Compass] separates ideas about governance into economic and social political thought. For example, Gandhi and Stalin supposedly both had similar economic perspectives (collectivist) but radically different social perspectives (libertarian vs authoritarian).

As politics is how laws are made, this is inherently lawful. Representing all politics in terms of two very general axes is not only a gross oversimplification, it is often used to put one's favored ideology as far away from Hitler or Stalin. This common use of a fallacy similar to the straw man makes this chart evil.

Like the USDA soil chart, the political compass has actually been [https://knowyourmeme.com/memes/political-compass used as an alignment chart], largely to mock the original political compass chart.
|-
|Neutral Evil
|{{w|QAPF diagram|QAPF rock diagram}}
|This diagram is used to classify coarse-grained felsic (low magnesium and iron) igneous rocks by the relative volumes of the minerals quartz, alkali feldspars, plagioclase feldspars, and feldspathoids in the rock. It consists of two ternary diagrams - quartz and feldspathoid minerals cannot coexist (they will react to form feldspars) so only three of these components will be in any given rock. Rocks in the upper triangle of the diagram contain quartz, with rocks with more quartz plotting closer to the top, while rocks in the lower triangle contain feldspathoids, with rocks with more feldspathoids plotting lower. Rocks closer to the left corner of the diagram contain more alkali feldspar and rocks closer to the right corner contain more plagioclase feldspar. The field on the diagram for granite is labeled in the comic, but each area outlined on the diagram has it's own rock name (monzonite, syenite, granodiorite, etc.). All the rocks that the QAPF diagram is used to classify look superficially like granite, but their chemistry, mineralogy, and origin differ.
The QAPF diagram and the names of the more obscure rock types on it can be somewhat arcane, which may be why it is considered evil here.
|-
|Chaotic Evil
|Omnispace classifier
|The other eight diagrams shown in this comic, squished together into one, with the shapes of the diagrams corresponding to those of the originals. The diagram is labeled chaotic, since it does not have a simple geometrical shape. Probably self-referential humour, in that the diagram created for this comic is considered to be chaotically evil.
|}

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

{{comic discussion}}



[[Category:Charts]]
[[Category:Biology]]
[[Category:Chemistry]]
[[Category:Physics]]
[[Category:Geology]]
[[Category:Language]]
[[Category:Fiction]]
[[Category:Politics]]