The gm.general-mathematics tag has no wiki summary.

**2**

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544 views

### Has the notion of “space” been reconsidered in 20th century?

The original title, "has the bases of geometry been reconsidered in 20th century" of this question refers to Riemann's paper "On the Hypotheses which lie at the Bases of Geometry"， an English version ...

**0**

votes

**2**answers

534 views

### What constitutes the division between discrete and non-discrete math? Are there any math subject where it's being blurred? [closed]

I often heard about this division but always in a non-formal manner. What constitutes it? Is it a limit operation? Or a fundamental distinction between countable and uncountable sets? And what math ...

**2**

votes

**1**answer

292 views

### Computer algebra system (CAS) with good re-presenting or transformation support

Such heavy-weight transformations as expanding or factoring are provided by most of CAS-es, but what about light-weight, but a useful transformations, like "reorder some terms to make expression more ...

**6**

votes

**8**answers

2k views

### Beautiful theorems with short proof [closed]

I like to ask for beautiful mathematical theorems with short proof. A proof is short in my sense if it is at most one page assuming basic notations and very basic results a second year student will ...

**1**

vote

**1**answer

218 views

### Distance calculation in metric space

Dear All,
I want to calculate the distance between two sets in which the maximum distance between the sets are minimized. Formally problem defined as,
$\displaystyle \min_{a \in A} \max_{b \in B}$ ...

**3**

votes

**4**answers

797 views

### Another Chicken or Egg: Sequence or Series

This is a side question which is more motivated by teaching than research.
First, I am trying to convince myself that sequences appear before series (as numerical approximations to "interesting" ...

**1**

vote

**0**answers

170 views

### Allocation game optimal strategy

There are two players, Alice and Bob. There is an initial pool of 100 dollars. Alice proposes an allocation of the dollars (real numbers, not necessarily integers), and Bob can either accept or ...

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**0**answers

233 views

### Modelling the difficulty of mental calculation. [closed]

Are you aware of any work that tries to model the difficulty of evaluating a formula mentally (for your average, numerate, person, not a trained mental calculator)?
For instance, evaluating an ...

**1**

vote

**1**answer

385 views

### Quantifiers in function definition — is this legitimate?

I've encountered a working paper in which the author discusses two different notions about the legitimate definition of a certain functional. He expresses these notions using the universal and ...

**3**

votes

**0**answers

118 views

### Reference request: name of a transform

Define a transform on polynomials which is linear and acts on each monomial as $$\widehat{z^k} = \frac{(1+z)(2+z)\ldots(k+z)}{k!}.$$ Does anyone know whether this has a name (and therefore has been ...

**16**

votes

**3**answers

915 views

### Results that are easy to prove with a computer, but hard to prove by hand [closed]

Consider the assertion:
There is no completely multiplicative function $f:\mathbb{N}\rightarrow \{\pm 1\}$ with $\left|\sum_{n\leq x}f(n)\right|\leq 2$ for all $x\geq 0$.
One can write a very short ...

**3**

votes

**0**answers

233 views

### Seminar Notes Repository

On Seminars, people actually talk a lot more about motivations than when they write in paper. It would be a good idea if there is an online repository where people can upload notes (handwritten, ...

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**9**answers

1k views

### math circles video lectures for school children?

Hello,
I am from India. I find the mathoverflow amazing.
I have a question: Are there any good quality video lectures on school math topics?
There are a lot of high quality lectures available on ...

**11**

votes

**4**answers

739 views

### Applications of Zariski topology outside alg. geometry

Are there applications of the Zariski topology in mathematics that are not within the scope of algebraic geometry (including schemes and algebraic groups) ?
There is an older question with a similar ...

**0**

votes

**3**answers

656 views

### Simplifying finite sum over 1/(ax+b)

Can I simplify:
\begin{equation}
\sum_{x=x_0}^{x_1} \frac{1}{ax+b}
\end{equation}

**12**

votes

**1**answer

501 views

### Continued fractions and projective resolutions

Hello,
This question might be vague and not thought-through enough.
If we have a real positive number $x$, we can start to write it as a continued fraction:
$x = a_0 + \frac{1}{x_1} , \ldots , ...

**6**

votes

**2**answers

500 views

### Where is the Euler/Goldbach correspondence?

I know that there is a 1965 volume containing the Euler/Goldbach correspondence, but I'm interested in looking at the original manuscripts. I'm not finding anything at University of Basel or ...

**5**

votes

**0**answers

526 views

### Open problems with practical outcome in a visible future ? [closed]

I believe that any non-trivial idea will sooner or later find application in real life.
However "sooner" is better than "later":)
If we look at famous open problems - e.g. Millennium Prize problems - ...

**1**

vote

**1**answer

210 views

### “Highly balanced” periodic functions

The function $f(x) = e^{2\pi ix}$ on the domain $\mathbb{R}/\mathbb{Z}$ has the property that, for every $n > 1$ and every $x$, $\displaystyle \sum_{i = 0}^{n-1} f(x + \frac{i}{n}) = 0$.
Other ...

**15**

votes

**7**answers

1k views

### Unexpected applications of the fact that nth degree polynomials are determined by n+1 points

I had a funny idea for proving an identity in Euclidean geometry. While it didn't end up being a very nice proof strategy in my case, I would still like to collect nice examples of where the proof ...

**2**

votes

**2**answers

780 views

### Sum of products of exponentials and polynomials

Hi,
I am looking for a closed-form expression for the finite sum of the product of an exponential function with a polynomial function --- that is, the sum
...

**4**

votes

**0**answers

626 views

### How to find a problem ??? [closed]

Hi All,
To do math, of course every one always finds some interesting problems and then try to solve them and then publish them as articles. In particular, in doing PhD, thesis advisors normally give ...

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votes

**2**answers

963 views

### what part of using vieta's formulas violates quintic non-solvability? [closed]

You can write the n roots of an n degree polynomial in terms of its n coefficients, i.e., "Vieta's" formulas.
You can solve this system of nonlinear equations using Newton's method and the Jacobian. ...

**0**

votes

**0**answers

94 views

### Repeated function resulting in quadratic time.

Let $$r(f, x) = k$$ such that
$$f^k (x) < 2 \hbox{ and } f^{k-1} (x) \geq 2$$
For example $$r(n \rightarrow n-1, 2^n) = 2^n-1; r(n \rightarrow n/2, 2^n) = n.$$
For an arbitrary $c$, we have $$r( ...

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vote

**2**answers

953 views

### Normal distribution with positive SEMI-definite covariance matrix

Hi
In [1] is noted, that a covariance matrix is "positive- semi definite and symmetric". I wonder if it is possible to a multivariate normal distribution with a covariance matrix that is only ...

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votes

**0**answers

1k views

### Good math speakers [closed]

Physics has had great speakers and popularizers (Carl Sagan would be the first to come to my mind). Mathematics, on the other hand, seems to be short on this. At least that is my impression... Or am I ...

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votes

**3**answers

765 views

### Thom's Principle: rich structures are more numerous in low dimension

Marcel Berger states Thom's Principle as:
"rich structures are more numerous in low dimension,
and poor structures are more numerous in high dimension."
This is in
Geometry II
...

**75**

votes

**19**answers

10k views

### Mathematical habits of thought and action which would be of use to non-mathematicians

Once again I come to MO for help with something I'm writing for the public.
Which habits of mathematicians -- aspects of the way we approach problems, the way we argue, the way we function as a ...

**2**

votes

**5**answers

831 views

### Circumference of convex shapes

Here is a puzzle I found in "Mitteilungen der DMV" (roughly "Letters of the German Society of Mathematicians") issue 19/2011. It was posed by Alfred Schreiber in "Wie man Hasen fangt" (How to catch ...

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votes

**5**answers

4k views

### Changing field of study post-PhD

I am doing my PhD in algebraic graph theory, for not much more reason than that was what was available. However, I love deep structure and theory in mathematics, and I do not particularly want to be ...

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votes

**1**answer

683 views

### Stylistic question

I'm writing up a paper now where I'm the only author and have a stylistic question.
Should I write ''I'' or ''we'' as in ''I/we recall the definition...'' etc. I think this simple example will make ...

**1**

vote

**0**answers

168 views

### Finite topological dimension x local compactness

Of course, the two notions are independent one from the other, but often one of them implies the other under some additional hypotheses. For instance:
A topological vector space is finite dimensional ...

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**9**answers

3k views

### Dimensional Analysis in Mathematics

Is there a sensible and useful definition of units in mathematics? In other words, is there a theory of dimensional analysis for mathematics?
In physics, an extremely useful tool is the Buckingham Pi ...

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**14**answers

3k views

### What are some examples of “chimeras” in mathematics?

The best example I can think of at the moment is Conway's surreal number system, which
combines 2-adic behavior in-the-small with $\infty$-adic behavior in the large. The surreally
simplest element ...

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votes

**4**answers

2k views

### Where do surreal numbers come from and what do they mean?

I know about Conway's original discovery of the surreal numbers by way of games,
as well as Kruskal's way of viewing surreal numbers in terms of asymptotic behavior
of real-valued functions, leading ...

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votes

**3**answers

2k views

### An elementary problem in Euclidean geometry [closed]

This problem was first put to me by Luke Pebody (who did not know the answer at the time) and after some work I am yet to find a proof or counterexample. I would be grateful of any insights.
Call a ...

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votes

**2**answers

1k views

### Naturally occurring orderings

The are many orderings that naturally occur in interesting but seemingly unrelated circumstances. Here are some examples:
The volume spectrum of orientable hyperbolic 3-manifolds has order type ...

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**4**answers

2k views

### Overview of the interplay of Harmonic Analysis and Number Theory

I'm kind of disappointed that the question here was never sharpened.
The Laplacian $\Delta$ on the upper half-plane is $-y^{2}(\partial^{2}/\partial x^{2}+\partial^{2}/\partial y^{2}))$. Suppose $D$ ...

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votes

**10**answers

824 views

### Examples of “Unusual” Classifications

When one says "classification" in math, usually one of a handful of examples springs to mind:
-Classification of Finite Simple Groups with 18 infinite families and 26 sporadic examples (assuming one ...

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votes

**14**answers

3k views

### A set for which it is hard to determine whether or not it is countable.

I got thinking recently, while trying to come up with a problem, that I did not know of any sets which were reasonable to define but for which it was very difficult to determine whether or not they ...

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**3**answers

828 views

### P vs. NP resistant problems

According to Stephen Cook on wikipedia, http://en.wikipedia.org/wiki/P_versus_NP_problem
...it would transform mathematics by allowing a computer to find a formal proof of any theorem which has a ...

**91**

votes

**14**answers

11k views

### When should a supervisor be a co-author?

What are people's views on this? To be specific: suppose a PhD student has produced a piece of original mathematical research. Suppose that student's supervisor suggested the problem, and gave a few ...

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votes

**0**answers

593 views

### How many projects do you work on concurrently? [closed]

I was wondering how many concurrent research projects a typical math researcher works on at a given time. I ask because I currently have the oppertunity to start a second project on something I'm ...

**2**

votes

**1**answer

300 views

### A question on a special type of function

Suppose I have a function $f$, and positive integers $x$ and $y$ such that $x$ is a
square, $x \ne y$ and $y \ne \sqrt{x}$.
Now, assume that:
$|\frac{f(x)}{y} - \frac{f(y)}{x}| > 2$
...

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votes

**0**answers

1k views

### Where does Aphex Twin's “windowlicker” equation come from? [closed]

$\Delta M_i^{-1} = -\alpha \sum\limits_{n=1}^N D_i [n] \left[\sum\limits_{j \in C[i]} F_{ji} [n-1] + Fext_i [n^{-1}]\right]$
This is the name of the second song on Aphex Twin's album "Windowlicker". ...

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**3**answers

841 views

### Spaces with a quasi triangle inequality

How do you call a space with a function which is symmetric, non negative, positive definite and which satisfies a quasi-triangle inequality:
$d(x,z) \leq C( d(x,y)+d(y,z) )$
for all $x,y,z$ and some ...

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votes

**3**answers

912 views

### Card game / options pricing / Brownian bridge question

We play a game. I shuffle a deck of cards and start dealing them face up. After any card you can say "stop", at which point I pay you 1 dollar for every red card dealt and you pay me 1 for every black ...

**14**

votes

**12**answers

2k views

### Why semigroups could be important?

There is known a lot about the use of groups -- they just really appear a lot, and appear naturally. Is there any known nice use of semigroups in Maths to sort of prove they are indeed important in ...

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votes

**2**answers

891 views

### Are there uncountably many essentially inequivalent versions of Mathematics?

Hi everyone,
Disclaimer 1: logic and set theory are a long way from my field, so apologies in advance if I demonstrate extreme ignorance or stupidity, and please correct me if (when?) I write stupid ...

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vote

**0**answers

277 views

### Why semigroups are important? [closed]

There is known a lot about semigroups, mostly about their inner structure etc. But is there any use of semigroups in the general Maths -- like that of groups?