# Main Page

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− | < | + | <font size=5px>''Welcome to the '''explain [[xkcd]]''' wiki!''</font> |

We have collaboratively explained [[:Category:Comics|'''{{#expr:{{PAGESINCAT:Comics}}-9}}''' xkcd comics]], | We have collaboratively explained [[:Category:Comics|'''{{#expr:{{PAGESINCAT:Comics}}-9}}''' xkcd comics]], | ||

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remain. '''[[Help:How to add a new comic explanation|Add yours]]''' while there's a chance! | remain. '''[[Help:How to add a new comic explanation|Add yours]]''' while there's a chance! | ||

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== Latest comic == | == Latest comic == | ||

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<span style="float:right;">[[{{LATESTCOMIC}}|'''Go to this comic explanation''']]</span> | <span style="float:right;">[[{{LATESTCOMIC}}|'''Go to this comic explanation''']]</span> | ||

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* If you're new to wikis like this, take a look at these help pages describing [[mw:Help:Navigation|how to navigate]] the wiki, and [[mw:Help:Editing pages|how to edit]] pages. | * If you're new to wikis like this, take a look at these help pages describing [[mw:Help:Navigation|how to navigate]] the wiki, and [[mw:Help:Editing pages|how to edit]] pages. | ||

− | * Discussion about various parts of the wiki is going on at [[Explain XKCD:Community portal]]. | + | * Discussion about various parts of the wiki is going on at [[Explain XKCD:Community portal]]. Share your 2¢! |

* [[List of all comics]] contains a complete table of all xkcd comics so far and the corresponding explanations. The red links ([[like this]]) are missing explanations. Feel free to help out by creating them! [[Help:How to add a new comic explanation|Here's how]]. | * [[List of all comics]] contains a complete table of all xkcd comics so far and the corresponding explanations. The red links ([[like this]]) are missing explanations. Feel free to help out by creating them! [[Help:How to add a new comic explanation|Here's how]]. | ||

== Rules == | == Rules == | ||

− | Don't be a jerk. | + | Don't be a jerk. There are a lot of comics that don't have set in stone explanations; feel free to put multiple interpretations in the wiki page for each comic. |

If you want to talk about a specific comic, use its discussion page. | If you want to talk about a specific comic, use its discussion page. |

## Revision as of 05:35, 4 March 2013

*Welcome to the explain xkcd wiki!*

We have collaboratively explained **5** xkcd comics,
and only 1851
(37020%)
remain. **Add yours** while there's a chance!

## Latest comic

Existence Proof |

Title text: Real analysis is way realer than I expected. |

## Explanation

This explanation may be incomplete or incorrect: Needs more work, especially an explanation of the G() function. |

In mathematics, an existence proof is a proof that only shows that an object with a specific property exists, but does not tell what this object is. For instance, if f is a continuous function such that f(0) = 0 and f(100) = 2, it is easy to prove that there exists an x between 0 and 100 such that f(x) = 1 (as in the comic). However, this proof gives no way to find such an x.

In many situations, a proof of existence is enough to satisfy a mathematician, but in others, it is desirable to actually identify the object whose existence has been proven.

The full statement itself seems like a solution to some kind of function composition problem. Seems like what the class has proven is that if you apply certain function G(x) to a starting point of function f(0), then what it will do is just give you a value of f(x) at some other value of x, existence of which is stated to be proven.

In the comic, Miss Lenhart (and students) take this one step further, by taking up arms to destroy the function value, which they have proven to exist. In the last panel, some students off screen begin to wonder if they are in the right class, as normal math classes do not take up swords to fight abstract concepts.^{[citation needed]} Another student remarks that they are finally in the right math class, implying that this is the kind of thing they wanted from their math curriculum all along.

The phrase "*We ride*" is commonly used in rallying battle cries, particularly in fantasy or medieval dramas where characters are preparing to enter combat on horseback. Variations of the phrase are used several times in *The Lord of the Rings*, for example..

The title text refers to Real Analysis, a branch of mathematics dealing with real numbers and real-valued functions (as opposed to studies dealing with imaginary numbers in the complex plane). As the speaker implies, Real Analysis is supposed to remain confined to the theoretical realm of mathematics; certainly nobody signing up for such a class would ever expect to be embroiled in a crusade against intangible constructs! Taken out of its mathematical context, "analysis" literally means "breaking down", referring to the teacher's intention to cut things up with a sword. The use of the neologism "realer" conveys that the situation has suddenly developed unusually high stakes, in a manner similar to the phrase "shit just got real". This nuance would be lost if the word "realer" were replaced with the technically correct phrasing of "more real".

This may be a continuation of 982: Set Theory, where numbers were "executed" to prove a point.

## Transcript

- [Miss Lenhart stands in front of a whiteboard and points at calculations written on it.]
- Miss Lenhart: There exists some number x such that f(x)=G(f(0))=1.

- [Miss Lenhart moves her arm in a frameless panel.]
- Miss Lenhart: Oh yes.
- Miss Lenhart: Somewhere out there, it exists.

- [Zoom-in on Miss Lenhart raising a fist.]
- Miss Lenhart: And we must find it... and
*destroy*it.

- [Miss Lenhart raises a sword.]
- Miss Lenhart: Grab your swords, students! We ride!
- Student #1 (off-screen): I think I'm in the wrong math class?
- Student #2 (off-screen): I'm finally in the right one.

*Is this out of date? *
.

## New here?

You can read a brief introduction about this wiki at explain xkcd. Feel free to sign up for an account and contribute to the wiki! We need explanations for comics, characters, themes, memes and everything in between. If it is referenced in an xkcd web comic, it should be here.

- If you're new to wikis like this, take a look at these help pages describing how to navigate the wiki, and how to edit pages.

- Discussion about various parts of the wiki is going on at Explain XKCD:Community portal. Share your 2¢!

- List of all comics contains a complete table of all xkcd comics so far and the corresponding explanations. The red links (like this) are missing explanations. Feel free to help out by creating them! Here's how.

## Rules

Don't be a jerk. There are a lot of comics that don't have set in stone explanations; feel free to put multiple interpretations in the wiki page for each comic.

If you want to talk about a specific comic, use its discussion page.

Please only submit material directly related to —and helping everyone better understand— xkcd... and of course *only* submit material that can legally be posted (and freely edited.) Off-topic or other inappropriate content is subject to removal or modification at admin discretion, and users who repeatedly post such content will be blocked.

If you need assistance from an admin, feel free to leave a message on their personal discussion page. The list of admins is here.