Skip to main content
Search type Search syntax
Tags [tag]
Exact "words here"
Author user:1234
user:me (yours)
Score score:3 (3+)
score:0 (none)
Answers answers:3 (3+)
answers:0 (none)
isaccepted:yes
hasaccepted:no
inquestion:1234
Views views:250
Code code:"if (foo != bar)"
Sections title:apples
body:"apples oranges"
URL url:"*.example.com"
Saves in:saves
Status closed:yes
duplicate:no
migrated:no
wiki:no
Types is:question
is:answer
Exclude -[tag]
-apples
For more details on advanced search visit our help page
Results tagged with
Search options not deleted user 1162

Questions designed to generate a "big list" of certain results, examples, conjectures, etc. via many individual answers, each contributing one or a few instances. Such a question should typically be in Community Wiki mode (CW); after asking, please, flag for moderators attention requesting the question to be made CW.

31 votes

Blackbox Theorems

I think the Uniformization theorem is an example of blackbox theorem : any simply connected Riemann surface is conformally equivalent to either the open unit disk, the complex plane or the Riemann sph …
2 votes

German mathematical terms like "Nullstellensatz"

There is Ahlfor's scheibensatz in complex function theory, which is a generalization of Ahlfors five islands theorem
28 votes

Examples of common false beliefs in mathematics

As a teaching assistant in an elementary number theory course, I've seen the following quite often : If $a$ divides $bc$ and $a$ does not divide $b$, then $a$ divides $c$. That's of course true if $ …
9 votes

Examples of common false beliefs in mathematics

I have heard the following a few times : "If $f$ is holomorphic on a region $\Omega$ and not one-to-one, then $f'$ must vanish somewhere in $\Omega$." $f(z)=e^z$ of course is a counterexample.
13 votes
12 answers
5k views

On proving that a certain set is not empty by proving that it is actually large

It happens occasionally that one can prove that a given set is not empty by proving that it is actually large. The word "large" here may refer to different properties. For example, one can prove that …
24 votes

Do you know important theorems that remain unknown?

I am not sure whether the following satisfies the OP's high standards for a good answer, but I thought the result was very interesting when I first learned about it a few years ago. Theorem. Let $ …
78 votes

Not especially famous, long-open problems which anyone can understand

I always enjoyed telling people about the Inscribed square problem : Does every (Jordan) curve in the plane contain all four vertices of some square? Update: Here is a variation due to Helge Tverbe …
112 votes

Famous mathematical quotes

"The Axiom of Choice is obviously true, the well-ordering principle obviously false, and who can tell about Zorn's lemma?" — Jerry Bona
55 votes
Accepted

Math puzzles for dinner

I really like the following puzzle, called the blue-eyed islanders problem, taken from Professor Tao's blog : "There is an island upon which a tribe resides. The tribe consists of 1000 people, with v …