Questions on problems that have yet to be completely solved by current mathematical methods.

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75
votes
4answers
4k views

What is the smallest number of $45^\circ-60^\circ-75^\circ$ triangles that a square can be divided into?

What is the smallest number of $45^\circ-60^\circ-75^\circ$ triangles that a square can be divided into? The image below is a flawed example, from http://www.mathpuzzle.com/flawed456075.gif ...
23
votes
14answers
2k views

How can we produce another geek clock with a different pair of numbers?

So I found this geek clock and I think that it's pretty cool. I'm just wondering if it is possible to achieve the same but with another number. So here is the problem: We want to find a number ...
23
votes
1answer
585 views

How to prove there are an infinite number of squarefree numbers of the form $2^p-1$?

How to prove there are an infinite number of squarefree numbers of the form $2^p-1$, where $p$ is prime? It is conjectured that all numbers of the form $2^p-1$ are squarefree. I've been having ...
22
votes
4answers
1k views

Can someone explain the ABC conjecture to me?

I am an undergrad and I know that the conjecture may have been proven recently. But in reading about it, I am entirely confused as to what it means and why it is important. I was hoping some of you ...
22
votes
5answers
413 views

Famous Problems Where We Only Know the Elementary

Define a graph with vertex set $\mathbb{R}^2$ and connect two vertices if they are unit distance apart. The famous Hadwiger-Nelson problem is to determine the chromatic number $\chi$ of this graph. ...
20
votes
2answers
823 views

Complex solutions for Fermat-Catalan conjecture

The Fermat-Catalan conjecture is that $a^m + b^n = c^k$ has only a finite number of solutions when $a, b, c$ are positive coprime integers, and $m,n,k$ are positive integers satisfying $\frac{1}{m} + ...
20
votes
1answer
528 views

Any proof to $\pi^{e}$'s irrationality?

I've searched for this for a while but get nothing... There are plenty of proofs to irrationality of $e$,$\pi$,$e^{\pi}$. However, I can't find a proof for $\pi^e$. More, when searching for this I ...
19
votes
4answers
2k views

Primes of the form $n^2+1$ - hard?

I met a student that is trying to prove for fun that there are infinitely many primes of the form $n^2+1$. I tried to tell him it's a hard problem, but I lack references. Is there a paper/book ...
18
votes
2answers
5k views

Has anyone found a “pattern” in prime numbers?

Yesterday I was having some fun trying to look for some patterns in primes; and I think I found something interesting (to me at least). I still have not found any lists of patterns already found, ...
18
votes
1answer
404 views

How many points can you find on $y=x^2$, for $x \geq 0$, such that each pair of points has rational distance?

Open problem in Geometry/Number Theory. The real question here is: Is there an infinite family of points on $y=x^2$, for $x \geq 0$, such that the distance between each pair is rational? The ...
16
votes
1answer
642 views

Why are these geometric problems so hard?

I was surprised to learn that both for the Moving Sofa Problem and Packing 11 Squares solutions have been proposed, but in either case the optimality of the proposed solution is, as of yet, only ...
16
votes
5answers
2k views

The main attacks on the Riemann Hypothesis?

Attempts to prove the Riemann Hypothesis So I'm compiling a list of all the attacks and current approaches to Riemann Hypothesis. Can anyone provide me sources (or give their thoughts on possible ...
16
votes
1answer
453 views

Status of a conjecture about powers of 2

I recently saw a conjecture on a blog ( http://blog.tanyakhovanova.com/?p=311 ) which the author refers to as the 86 conjecture. The conjecture claims that all powers of 2 greater than $2^{86}$ have a ...
16
votes
1answer
431 views

Odd perfect squares whose decimal representation consist only of 1's and o's

Are there any odd perfect squares (apart from the trivial 1), whose decimal representations only uses 1 and 0? Working modulo 8, we can get that the last 3 digits must be 001. However, since $4251^2 ...
13
votes
2answers
520 views

Are there any infinite sets that are not known to be either countable or uncountable?

Are there any known examples of sets that are definitely infinite, but where we don't know whether or not they're countable? I haven't heard of anything like this before, but it seems that there ...
13
votes
2answers
380 views

Status of the classification of non-finitely generated abelian groups.

From the Wikipedia on abelian groups: By contrast, classification of general infinitely-generated abelian groups is far from complete. How far are we from a classification exactly? It seems ...
13
votes
1answer
312 views

What are some of the major open problems in category theory?

What are some of the major open problems in category theory? Just curious - I'm interested in category theory.
13
votes
4answers
573 views

When is $\left\lfloor \frac {7^n}{2^n} \right\rfloor \bmod {2^n} \ne 0\;$?

Is $$\left\lfloor \frac {7^n}{2^n} \right\rfloor \bmod{2^n} \ne 0\;$$ always true when $n \ge 3$. Baker's theorem on transcendental numbers that provide bounds for diophantine equations may be ...
12
votes
1answer
214 views

$\tan (n) > n$ for infinitely many positive integers

I heard the following problem is open: $ \tan(n ) > n $ for infinitely many positive integers in radians. Does anyone know if it is still open or if any progress has been made on this ...
12
votes
1answer
293 views

Proving that this Game on Polygons Ends

About two years ago, I started thinking about the following problem: You're given an $N$ and an $S$, positive integers. You start with an $N$-gon that has positive integer labels at each vertex, such ...
11
votes
2answers
793 views

Why is Hodge more difficult than Tate?

There are strong connections between the Hodge and the Tate conjectures, mainly at the level of similarities and analogies. To quote from an answer of Matthew Emerton on MathOverflow: "[...] we ...
11
votes
0answers
649 views

Are there open problems in Linear Algebra?

I'm reading some stuff about algebraic K-theory, which can be regarded as a "generalization" of linear algebra, because we want to use the same tools like in linear algebra in module theory. There ...
10
votes
4answers
532 views

The value of $\sqrt{1-\sqrt{1+\sqrt{1-\sqrt{1+\cdots\sqrt{1-\sqrt{1+1}}}}}}$?

How to find value of $\sqrt{1-\sqrt{1+\sqrt{1-\sqrt{1+\cdots\sqrt{1-\sqrt{1+1}}}}}}$ ? I've calculated it by MATLAB for some finite terms and I've got : $0.3001 - 0.4201i$, but I don't know how to ...
10
votes
3answers
557 views

Solving P vs NP with computer

Is it possible to build a computer program that would (eventually) bring a solution to the P vs. NP question?
10
votes
3answers
1k views

Why has the Perfect cuboid problem not been solved yet?

Why hasn't Perfect Cuboid Problem been solved yet, whereas (possibly) more nontrivial ones such as FLT and Sphere packing have been solved? I understand that calling some problems more nontrivial ...
9
votes
10answers
917 views

Favourite open problem?

Do you have any favorite open problem? Let me mention one of my favorites. Let $A(\mathbb{T})$ be the Wiener algebra, that is, the linear space of absolutely convergent Fourier series on the unit ...
9
votes
2answers
797 views

What does the Hodge conjecture mean?

I read from the Internet that according to the Hodge conjecture, a certain harmonic differential form in a projective, non-singular algebraic variety is a rational linear combination of the cohomology ...
9
votes
2answers
540 views

Thoughts on the Collatz conjecture; integers added to powers of 2

I've had a thought about the Collatz conjecture (the 3n+1 problem). Suppose some number, C, diverges under the iteration. We first note that C must be odd because if C were even it would be halved ...
9
votes
0answers
172 views

What turmite runs the longest before becoming predictable?

When looking at 2D Turing machines, many of them eventually become predictable. For example, Langton's Ant, the champion 2-color 1-state turmite, develops a highway after 10,000 steps. Predictable ...
8
votes
5answers
1k views

How valid is the proposed P=NP solution for the 3-SAT problem?

Source link: http://romvf.wordpress.com/2011/01/19/open-letter/ (Referred from slashdot) The fact of existence of the polynomial algorithm for 3-SAT problem leads to a conclusion that P=NP. Is ...
8
votes
3answers
630 views

Branches of mathematics not having a general method to solve

I studied applied math, so each course (except abstract algebra) was dedicated to solution of a similar problems. After those courses it seems that every branch of mathematics has a developed theory ...
8
votes
4answers
1k views

What does proving the Collatz Conjecture entail?

From the get go: i'm not trying to prove the Collatz Conjecture where hundreds of smarter people have failed. I'm just curious. I'm wondering where one would have to start in proving the Collatz ...
8
votes
1answer
165 views

Independence results that cannot be established by forcing.

I read the Wikipedia article on Absoluteness recently and found mention of Shoenfield’s Absoluteness Theorem, which states that if $ \phi $ is any $ \Sigma^{1}_{2} $- or $ \Pi^{1}_{2} $-sentence of ...
8
votes
1answer
510 views

What are possibilities to disprove the Collatz Conjecture?

I was thinking about the Collatz Conjecture yesterday, and as opposed to trying to prove it, I was considering what would make the conjecture false. There were only two cases I could think of: We ...
8
votes
0answers
191 views

Weak version of Fortune's conjecture

Let $p\#=2\cdot3\cdot5\cdots p$ denote the primorial and $N(x)$ the smallest prime greater than or equal to $x$. Then Fortune's conjecture is that $N(p\#+2)-p\#$ is prime for all $p$. (Heuristic: to ...
7
votes
1answer
233 views

What is the importance of 3n in the Collatz Conjecture?

I'm not mathematician, so forgive me if I make wrong assumptions. I was wondering what the importance of the $3n$ is in the Collatz Conjuncture. If you just do $n + 1$, it seems you'll end up at $1$ ...
7
votes
2answers
300 views

Open problems in Mathematical Tomography?

Since I feel that Tomography can be applied to a wide range of sciences, I was wondering what the current open problems in Tomographic Reconstruction are. Furthermore, I am curious as to how these ...
7
votes
1answer
448 views

Any serious work on Lychrel numbers/$196$-Algorithm?

I've been googling around a little lately and have stumbled across the so called Lychrel problem. For a natural number $x$, let $Rx$ denote the number obtained by reversing the base-$10$ digits of $x$ ...
6
votes
2answers
240 views

How many partial order on a n-set?

Let $A$ be a set has $n$ element, my question is how many partial order on it? For $n=0,1$, $N_P(n)=1$ Case $n=2$, $N_P(n)=3$ Case $n=3$, $N_P(n)=19$ Is there a general formula? Update: It seems ...
6
votes
1answer
128 views

Minimal counterexamples of the isomorphism problem for integral group rings

The isomorphism problem for integral group rings asks if two finite groups $G,H$ are isomorphic when their integral group rings $\mathbb{Z}[G]$, $\mathbb{Z}[H]$ are isomorphic. Quite a lot has been ...
6
votes
1answer
404 views

Best place to find open questions / latest research

Is there a central wiki or something where open questions (and relevant research on them) takes place?
6
votes
0answers
93 views

Biggest Little Polyhedron

The Biggest Little Polygon problem asks for the polygon with greatest area where the largest diameter is 1. Let's add a dimension and find the largest volumes. What is the biggest little polyhedron ...
5
votes
1answer
267 views

A question on Paul Erdős's research on Egyptian fractions

A good day to everyone! I have a (somewhat) intriguing question regarding Paul Erdős's papers on Egyptian fractions (e.g., his 2nd paper during his mathematical career was about this topic). My ...
5
votes
2answers
760 views

Undergraduate Research Problems

I'm a third year undergrad with this summer off so would appreciate some material to look at. I took courses in Galois theory, Topology, Complex analysis, ... My main interest is in Analysis / ...
5
votes
1answer
154 views

What relationship(s) [if any] exist between primorial primes and palindromic primes?

Information on primorial primes are in the following hyperlinks: MathWorld - Primorial Prime Wikipedia - Primorial Prime On the other hand, we have the following hyperlinks providing information on ...
5
votes
1answer
289 views

Hausdorff Dimension of Arbitrary Julia Set

I am looking to find an exact solution to the Hausdorff dimension of a Julia set $J(f)$ for a polynomial $f: z \mapsto z^2 +c$ given an arbitrary $c$. I know this question is known for a number of ...
5
votes
1answer
101 views

Zhang's theorem and Polignac's conjecture

Yitang Zhang made a groundbreaking discovery when he proved that there are infinitely many pairs of prime numbers which differ by less than $70,000,000$. Zhang's theorem has been significantly ...
5
votes
0answers
77 views

Is Paley-13 graph a unit distance graph in 3D space?

The 13-node Paley graph has vertices 1 to 13 that are connected by an edge when their difference is one of the values $(1,3,4,9,10,12)$ Can this graph be put into 3D space so that all edges have ...
5
votes
0answers
210 views

Can the 57-cell be made in vZome without strut crossings?

Here's the 57-cell in vZome with lots of strut crossings: Is it possible to construct the 57-cell in vZome without any strut crossings? That is, 57 nodes, 171 struts, in the 57-cell / Perkel graph ...
4
votes
1answer
9k views

Is “P vs NP” problem solved?

Many people have tried to solve the very famous problem "P vs NP" and a lot of solutions are proposed. (e.g. A. D. Plotnikov, On the Relationship between Classes P and NP). But I couldn't find any ...