explain xkcd - User contributions [en]

1179: ISO 8601

2013-06-29T03:56:05Z

Rewsie: /* Explanation */

{{comic
| number = 1179
| date = February 27, 2013
| title = ISO 8601
| image = iso_8601.png
| titletext = ISO 8601 was published on 06/05/88 and most recently amended on 12/01/04.
}}

==Explanation==
{{w|Public service announcement}}: Two commonly used date formats are {{w|Date format by country|dd.mm.yyyy and mm/dd/yyyy}} (the symbols separating the values, as well as the year being 2 or 4 digits notwithstanding). These differences are often causes for debate. However, the comic explains that the {{w|International Organization for Standardization}} (ISO) has standardized dates in the yyyy-mm-dd format, in its {{w|ISO 8601}} standard.

The comic then lists many formats as "discouraged". This list starts with commonly used formats, which include the two above as well as other commonly used ones, such as dd/mm/yy. However the list then starts listing formats ranging from uncommon to absurd, such as writing the date partly in Roman numerals and painting the date in m-d-yy format with white paint onto a hissing black cat.

The ISO standard was published (to use yet another date format) on 5 June 1988 and amended on 1 December 2004, two dates given in the title text in mm/dd/yy format. Since the day values are less than 13, the format used demonstrates its ambiguity; it could be interpreted as other dates given in dd/mm/yy format (the last in several other formats as well). The dates are not written in ISO 8601 format, contradicting the advice in this comic, adding a level of metahumor.

The other mentioned formats are:

{| class=wikitable
! Date !! Explanation
|-
| 02/27/2013
| MM/DD/YYYY, used mostly in the US.
|-
| 02/27/13
| MM/DD/YY
|-
| 27/02/2013
| DD/MM/YYYY, used e.g. in South America, Canada ({{w|Date_and_time_notation_in_Canada|officially uses ISO 8601}}), New Zealand and Europe.
|-
| 27/02/13
| DD/MM/YY
|-
| 20130227
| YYYYMMDD, also allowed in ISO 8601
|-
| 2013.02.27
| YYYY.MM.DD, used in Japan
|-
| 27.02.13
| DD.MM.YY, used e.g. in Germany
|-
| 27-02-13
| DD-MM-YY, used in Denmark, Netherlands, Indonesia, India, Bangladesh, etc.
|-
| 27.2.13
| D.M.YY
|-
| 2013. II. 27.
| YYYY. MM. DD., with month as {{w|Roman numerals}}, used in Hungary.
|-
| 27⁄2-13
| D⁄M-YY
|-
| 2013.158904109
| Year and decimal fraction of year – 58/365, February 27 being the 58th day of the year. This representation marks the end of that day. Also allowed in ISO 8601.
|-
| MMXIII-II-XXVII
| Year-month-day in Roman numerals
|-
| MMXIII [and] LVII [over] CCCLXV
| Year and ''57''/365. This representation marks the start of the day, which is 57 days after the year started.
|-
| 1330300800
| {{w|Unix time|UNIX Timestamp}}, but for '''2012'''-02-27.
|-
| ((3+3)×(111+1)-1)×3/3-1/33
| Year/month/day with the parts written as arithmetic expressions, using just the digits 1 and 3. (The slashes are not to be interpreted as fraction lines.)
|-
| 27 [''on''] 02 [''on''] 2013
| An obfuscated date format not used ordinarily. This can be considered a compromise between the different formats: since we cannot agree on which position in the date the day, month and year parts shall be, we just write them all in the same place; we don't even need separators, which we cannot agree on either. On the other hand, reading it gets somewhat tricky...
|-
| 10/11011/1101
| Month/day/year in {{w|Binary number|binary}}.
|-
| 02/27/20/13
| Month/Day/Century/Year.
|-
| 0 [2,5] 1 [3] 2 [1,6,7] 3 [4] 7 [8]
| The large digits are to be placed at the positions listed above and below: 0 is used at positions 2 and 5, 1 is used on position 3, etc.; the result being 20130227
|-
| ''A cat with'' "2-27-13" ''painted on it, going'' HiSSSS
| In Western cultures, black cats and the number 13 are associated with bad luck. The cat might also just be angry that someone painted an (unstandardized) date on it.
|}

==Transcript==
:Public Service Announcement:

:Our different ways of writing dates as numbers can lead to online confusion. That's why in 1988 ISO set a global standard numeric date format. This is '''''the''''' correct way to write numeric dates:

:2013-02-27

:The following formats are therefore discouraged:
*02/27/2013
*02/27/13
*27/02/2013
*27/02/13
*20130227
*2013.02.27
*27.02.13
*27-02-13
*27.2.13
*2013. II. 27.
*27⁄2-13
*2013.158904109
*MMXIII-II-XXVII
*MMXIII [and] LVII [over] CCCLXV
*1330300800
*((3+3)×(111+1)-1)×3/3-1/33
*27 [''written on top of''] 02 [''written on top of''] 2013
*10/11011/1101
*02/27/20/13
*0 [2,5] 1 [3] 2 [1,6,7] 3 [4] 7 [8]
*''A cat, with the numerals'' 2-27-13 ''painted on it, going'' HISSSS

{{comic discussion}}

[[Category:Math]]

954: Chin-Up Bar

2013-06-21T06:36:41Z

Rewsie: /* Explanation */

{{comic
| number = 954
| date = September 21, 2011
| title = Chin-Up Bar
| image = chin up bar.png
| titletext = Those few who escaped found the emergency cutoff box disabled. The stampede lasted two hours and reached the bottom three times.
}}

==Explanation==
[[Black Hat]] is blocking traffic on the {{w|Escalator#Escalators: superlatives|longest escalator}} in the {{w|western hemisphere}}, the escalator in the {{w|Wheaton (WMATA station)|Wheaton station}} in {{w|Washington D.C.}}'s {{w|Washington Metro}}.

An {{w|escalator}} is a motorized stairway. Black Hat installs a {{w|chin-up bar}} at waist height. Chin-up bars are typically capable of holding up a 300 pound (130 kg) person without moving. Being at waist height makes it hard to duck under, and hard to hurdle. Either way, on a crowded escalator during a high traffic period, avoiding the bar will be extremely difficult. The first people would probably stumble backward to avoid it, which would collide them into the passengers behind them, creating a {{w|domino effect}} all the way down. As the escalator continues to move people forward, the wave of falling people is moving backward, however its {{w|Theory of special relativity|apparent speed}} will be slower than its actual speed.

That is the joke in the title text, that over two hours the wave can reach the bottom only three times, whereas if this were a simple staircase the event would only last once and be over as quickly as people can fall down.
The people that actually made it to the bottom were unable to use the emergency shutdown because Black Hat disabled it.

==Transcript==
:[Black Hat is standing on an escalator as it ascends. He is carrying a pole with what looks like a bracket on each end, resting on his shoulder. In front of him is Ponytail, and in front of her is a punk with spiked hair and pimples. Behind Black Hat is Cueball. Behind Cueball is a man wearing glasses with a goatee standing next to someone with short hair.]

:[The view closes on Black Hat and Cueball. In the background a girl can be seen standing on the descending escalator.]
:Cueball: This is a long escalator.
:Black Hat: 70 meters. Longest in the country.

:[In the background the girl from the last panel has now passed the group and a few other people can be seen descending.]

:Cueball: Why're you carrying a chin-up bar?
:Black Hat: Why aren't you wearing a hat?

:[The view opens up a bit more to show the two riders ahead, and the two behind.]
:Cueball: I'm not really a hat person.
:Black Hat: And I'm not really a Not-carrying-a-chin-up-bar person.

:[Close up on Cueball]

:[The view opens up to show the same people in the first panel. They're near the top of the escalator now and Ponytail is beginning to step off.]
:Cueball: Seriously, why did you bring it?
:Black Hat: How should I know? I'm not a psychologist.

:[As Black Hat steps off the escalator he turns and installs the chin-up bar such that it blocks people from leaving the escalator, about waist height. Cueball turns to observe what Black Hat is doing.]
:''Twist''
:''Click click''

:[They get onto the descending escalator. The man with glasses and a goatee and his companion are blocked from leaving the escalator by the chin-up bar.]

:[The next panel is large.]
:[The view shows an extended section of the escalator, the top right has become a pile of people all squished together and on top of each other. One person has grabbed another by the hair and is standing on a third person in an attempt to not fall. Someone is falling off the pile and another person is running down the escalator to avoid them. People closer to the bottom of the escalator are looking horrified at the scene ahead of them. In the background hat man and his companion are visible. Black Hat is looking toward the bottom of the escalator, not caring or noticing the chaos unfolding. Cueball looks back pensively.]

==Trivia==
*It would appear that the goatee'd man behind Cueball is the psychologist from [[435: Purity]], and that the person he is with is the sociologist from the same comic.

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

770: All the Girls

2013-06-19T05:13:43Z

Rewsie: /* Explanation */

{{comic
| number = 770
| date = July 23, 2010
| title = All the Girls
| image = all the girls.png
| titletext = You know that I'll never leave you. Not as long as she's with someone.
}}

==Explanation==
A young couple ([[Cueball]] and [[Megan]]) are in love. In the first panel, Cueball says he's lucky to have Megan, a perfectly fine thing to say to someone when you're in love. In the second panel, Cueball tells Megan he loves her most out of all the girls in the world, which is again a perfectly fine thing to say when you're in love. Trouble sets in, however, in the third panel, where Cueball offers his qualifying statement, that he loves Megan the most of the subset of girls who also love Cueball back.

Now, on its surface it would appear that Cueball is making a hollow statement, in that the subset of girls who love him back must be smaller than the set of all the girls in the world, and we assume, because we are nerds, that that subset is probably only a few girls in size. To be optimistic, though, presume that Cueball, due to his smooth head and sentimental heart, is loved by nearly all the girls in the world, and so his sentiment is still very sweet.

The title text, however, crushes any optimism one might have in the situation. Written in Cueball's voice, we have another compliment/qualifier pair. Cueball assures Megan that he'll never leave her—so long as she's with someone. Cueball clearly has an unrequited love for another, and so really is being as shitty as we all thought he was originally. The world can be a cruel place.

It's also most likely a reference to the {{w|stable marriage problem}}, which is usually stated as: Given ''n'' men and ''n'' women, can they all be married off in such a way that there is no possible "adulterous" pairing that both the man and woman would prefer over their current partner? It turns out the answer is yes, and there are even algorithms that can be used to find such a set of marriages. However, such algorithms don't usually give people their first choice, just their first choice among potential partners who prefer them to all the alternatives. The algorithms also favor either the men or the women, so one side will typically get closer to their ideal preferences than the other. Such algorithms do get in used in situations like assigning medical students to residencies (technically it's a polygamous generalization, but it's basically the same idea), in which case it's biased in favor of the medical students.

In the comic [[Cueball]] and [[Megan]] appear to be a couple arranged through a stable marriage algorithm. In most cases that would mean that they both have potential partners that they would prefer over the one their with, and the only reason that they aren't with that person is that their love was unrequited. That leaves both of them with a certain amount of emotional baggage that most people would consider detrimental to stable marriage. In short, while a stable marriage algorithm may provide good solutions to certain matching problems, it may not be the best way to produce actual stable marriages.

==Transcript==
:[Cueball and Megan are standing together.]
:Cueball: I'm so lucky to have you.

:Cueball: I love you most out of all the girls in all the world

:[They embrace.]
:Cueball: who love me back.

==Trivia==
*In [[explain xkcd]] lore, the blog explanation of this comic was the first time the name [[Cueball]] was used. Berg also called [[Megan]] "Cutie" but it was later found that she was referred to by name in comic.

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

604: Qwertial Aphasia

2013-06-13T09:41:37Z

Rewsie: /* Explanation */

{{comic
| number = 604
| date = July 1, 2009
| title = Qwertial Aphasia
| image = qwertial_aphasia.png
| titletext = If this were SMBC, the alt-text drawing thingy would be a giraffe hooker fluttering her eyelashes.
}}

==Explanation==
[[Randall]] has invented the name "Qwertial Aphasia", to describe the common experience of having a word, from a spoken conversation, accidentally spill over into something one is typing, often with humorous results.

{{w|Aphasia}} is a class of medical conditions which affect the production and understanding of language. The description "Qwertial" probably refers to the position of the top row of letters in the most common keyboard arrangement, the {{w|QWERTY}} keyboard layout.

The joke set up in the comic comes from the substitution of the word 'giraffe' for the word 'frequently', which changes the whole meaning of the sentence. The original sentence would have been 'I can't afford to keep eating out this frequently.' The unintentional replacement makes 'giraffe' the object of the sentence, and implies that Cueball is 'eating out' (slang for {{w|cunnilingus}}) a giraffe. He tries to correct himself but the damage is done.

Another possible reading is that Cueball is correcting his first statement, explaining that this happens more often than just "sometimes".

The title text continues the image of a giraffe as a sexual object - in particular, one which costs money. SMBC refers to the comic [http://www.smbc-comics.com/ Saturday Morning Breakfast Cereal], a whimsical joke-a-day comic which comes with a second illustration, which can be seen by mousing over a button known as the "votey". This additional panel often serves as a second punchline in the same way as the title text does in xkcd.

==Transcript==
:I hate how when I'm talking while I type, sometimes I accidentally type a word I'm saying.
:[Cueball is sitting at a computer.]
:Computer: Wanna go get food later?

:[A woman runs over, holding a giraffe.]
:Woman: Check out what I found in the closet!
:''Type type''
:Cueball [Typing]: Sorry, I really shouldn't.

:Cueball [talking]: Aww, what an adorable stuffed giraffe!
:''Type type''
:Cueball [typing]: I can't afford to keep eating out this giraffe.

:''Frequently!'' I meant ''"frequently"''!

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

575: Tag Combination

2013-06-13T08:24:26Z

Rewsie: /* Explanation */

{{comic
| number = 575
| date = April 29, 2009
| title = Tag Combination
| image = tag combination.png
| titletext = I love Eileen / and want you to love her / When you're around / I'm one floor above her / If you could see / just how much I adore her / Oh, that pretty red dress / I'd do anything for her / (Too ra loo ra too ra loo rye ayy)
}}

==Explanation==
{{incomplete|If people could elaborate on the specific tags used in the comic, that would be great. Not a music buff, don't know much about these tags.}}
Song tags are a form of file {{w|Metadata}} used to categorize music. Tags will typically describe the content and genre of the song, and many music organization programs and services will allow users to find all songs that contain a particular tag; so when a user searches for "Country breakup music," they will receive a list of {{w|Country music|country}} songs about breaking up.

In this comic, [[Cueball]] tests [[Megan]]'s claim that she can make a song name for any set of tags by coming up with a collection of mostly unrelated words: "{{w|lesbian}} {{w|voyeurism}} {{w|one-hit wonder}} {{w|Mashup (music)|mash-up|}}." In response, Megan almost immediately replies with two song titles that look like they would fit the tags well.

Megan's first title, "I Wish That Stacy's Mom Had Jessie's Girl" is a ''mash-up'' of Jessie's Girl by Rick Springfield, and Stacy's Mom by Fountains of Wayne, which were both ''one-hit-wonders''.
The second title, "When You Come on Eileen I Touch Myself" is a ''mash-up'' of Come on Eileen by Dexy's Midnight Runners, and I Touch Myself by [http://en.wikipedia.org/wiki/Divinyls Divinyls].

The title text is a set of potential lyrics to Megan's second title.

==Transcript==
:Cueball: So you can come up with a song title fitting any tag combination?
:Megan: Try me.
:Cueball: Lesbian voyeurism one-hit wonder mash-up.
:Megan: "I wish that Stacey's Mom had Jessie's Girl."

:Cueball: Well, that was one, but-
:Megan: "When you Come On Eileen I touch myself."
:Cueball: Okay, wow.

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

575: Tag Combination

2013-06-13T08:01:05Z

Rewsie: /* Explanation */

{{comic
| number = 575
| date = April 29, 2009
| title = Tag Combination
| image = tag combination.png
| titletext = I love Eileen / and want you to love her / When you're around / I'm one floor above her / If you could see / just how much I adore her / Oh, that pretty red dress / I'd do anything for her / (Too ra loo ra too ra loo rye ayy)
}}

==Explanation==
{{incomplete|If people could elaborate on the specific tags used in the comic, that would be great. Not a music buff, don't know much about these tags.}}
Song tags are a form of file {{w|Metadata}} used to categorize music. Tags will typically describe the content and genre of the song, and many music organization programs and services will allow users to find all songs that contain a particular tag; so when a user searches for "Country breakup music," they will receive a list of {{w|Country music|country}} songs about breaking up.

In this comic, [[Cueball]] tests [[Megan]]'s claim that she can make a song name for any set of tags by coming up with a collection of mostly unrelated words: "{{w|lesbian}} {{w|voyeurism}} {{w|one-hit wonder}} {{w|Mashup (music)|mash-up|}}." In response, Megan almost immediately replies with two song titles that look like they would fit the tags well.

Megan's first title, "I Wish That Stacy's Mom Had Jessie's Girl" is a ''mash-up'' of Jessie's Girl by Rick Springfield, and Stacy's Mom by Fountains of Wayne, which were both ''one-hit-wonders''.
The second title, "When You Come on Eileen I Touch Myself" is a ''mash-up'' of Come on Eileen by Dexy's Midnight Runners, and I Touch Myself by The Divinyls.

The title text is a set of potential lyrics to Megan's second title.

==Transcript==
:Cueball: So you can come up with a song title fitting any tag combination?
:Megan: Try me.
:Cueball: Lesbian voyeurism one-hit wonder mash-up.
:Megan: "I wish that Stacey's Mom had Jessie's Girl."

:Cueball: Well, that was one, but-
:Megan: "When you Come On Eileen I touch myself."
:Cueball: Okay, wow.

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