User Conifold

18 votes

2 answers

912 views

Are there non-standard counterexamples to the Fermat Last Theorem?

asked Jul 28, 2016 at 2:57

17 votes

1 answer

670 views

Are there spaces that 'look the same' at every point, but are not homogeneous?

geometry differential-geometry riemannian-geometry

asked May 28, 2015 at 1:30

13 votes

2 answers

1k views

Why do we know that Gödel sentences are true in the standard model of set theory, but do not know if the continuum hypothesis is?

logic set-theory model-theory

asked Jun 30, 2015 at 21:36

13 votes

2 answers

454 views

Is Archimedes's method for computing volumes equivalent to Cavalieri's?

integration geometry

asked Jan 12, 2015 at 22:11

11 votes

1 answer

2k views

What is the reflection across a parabola?

complex-analysis geometry geometric-construction reflection

asked May 22, 2015 at 22:27

11 votes

1 answer

223 views

Is there a clever way to find a smaller number that produces the Euclidean algorithm of given length?

number-theory elementary-number-theory modular-arithmetic euclidean-algorithm

asked May 5, 2016 at 20:11

10 votes

3 answers

57k views

Are triangles the strongest shape?

geometry optimization calculus-of-variations

asked Aug 12, 2015 at 4:23

9 votes

2 answers

382 views

How many different products can be formed by multiplying $n$ numbers at most once?

combinatorics number-theory

asked Jun 27, 2017 at 23:27

7 votes

2 answers

1k views

What is the multiplicative order of a product of two integers $\mod n$?

group-theory number-theory modular-arithmetic prime-factorization

asked Aug 29, 2018 at 21:46

7 votes

1 answer

781 views

Why is the powerset axiom more acceptable than the axiom of choice?

soft-question set-theory model-theory axiom-of-choice

asked Aug 20, 2014 at 22:17

7 votes

1 answer

3k views

Functions with every point being a Lebesgue point

real-analysis integration measure-theory lebesgue-integral lebesgue-measure

asked Jul 7, 2014 at 22:19

6 votes

1 answer

590 views

Partial order on cardinalities without the axiom of choice

reference-request logic set-theory cardinals axiom-of-choice

asked Jun 17, 2014 at 21:49

6 votes

1 answer

412 views

Is there a theory of integration in elementary terms for definite integrals?

calculus integration definite-integrals closed-form elementary-functions

asked Aug 18, 2014 at 20:18

6 votes

1 answer

384 views

How do inconsistent arithmetics get around Gödel incompleteness?

logic model-theory axioms incompleteness

asked Nov 11, 2015 at 20:36

6 votes

1 answer

687 views

Circle inversion and the Pappus chain paradox

geometry circles transformation mobius-inversion

asked Jan 25, 2018 at 22:48

5 votes

1 answer

350 views

Are all rationally parametrized plane curves algebraic? How does one find their degree?

algebraic-geometry polynomials algebraic-curves plane-curves

asked Jan 15, 2016 at 0:48

5 votes

2 answers

374 views

Can one prove existence of incommensurables without the Pythagorean theorem?

geometry logic model-theory irrational-numbers

asked Aug 28, 2014 at 19:10

5 votes

1 answer

539 views

Finding covering system of congruences with prescribed moduli

number-theory elementary-number-theory

asked May 21, 2014 at 23:53

4 votes

0 answers

158 views

Can existence of aleph one be proved without the power set axiom? [duplicate]

logic set-theory

asked May 24, 2014 at 22:08

4 votes

1 answer

1k views

What is the dual space in the strong operator topology?

functional-analysis operator-theory hilbert-spaces banach-spaces

asked May 29, 2014 at 21:54

4 votes

1 answer

72 views

How many integer matrices have spectral radius bounded by a constant?

linear-algebra matrices spectral-radius

asked Jul 23, 2021 at 3:36

3 votes

1 answer

706 views

Can hyperreal numbers be studied 'naively', like surreal numbers?

logic nonstandard-analysis

asked May 29, 2014 at 0:55

3 votes

1 answer

278 views

Banach valued sequence spaces $\ell^p(X)$

functional-analysis reference-request banach-spaces lp-spaces

asked Jul 20, 2014 at 1:24

3 votes

0 answers

92 views

Is there an intuitive reason why hippopede, the intersection curve of a sphere and a cylinder, is traced by composing two rotational motions?

geometry differential-geometry intuition recreational-mathematics kinematics

asked Jan 15, 2015 at 18:22

2 votes

1 answer

393 views

Are order isomorphic real closed fields isomorphic?

field-theory model-theory ordered-fields

asked Aug 7, 2014 at 19:55

0 votes

1 answer

122 views

Is there a formalisation of set theory where unions can be taken over some classes that are not a priori known to be sets?

logic set-theory

asked May 25, 2014 at 3:49

0 votes

1 answer

206 views

Non-convex functions and their supporting hyperplanes

geometry convex-analysis convex-geometry

asked Mar 8, 2020 at 1:26

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27 Questions

Are there non-standard counterexamples to the Fermat Last Theorem?

Are there spaces that 'look the same' at every point, but are not homogeneous?

Why do we know that Gödel sentences are true in the standard model of set theory, but do not know if the continuum hypothesis is?

Is Archimedes's method for computing volumes equivalent to Cavalieri's?

What is the reflection across a parabola?

Is there a clever way to find a smaller number that produces the Euclidean algorithm of given length?

Are triangles the strongest shape?

How many different products can be formed by multiplying $n$ numbers at most once?

What is the multiplicative order of a product of two integers $\mod n$?

Why is the powerset axiom more acceptable than the axiom of choice?

Functions with every point being a Lebesgue point

Partial order on cardinalities without the axiom of choice

Is there a theory of integration in elementary terms for definite integrals?

How do inconsistent arithmetics get around Gödel incompleteness?

Circle inversion and the Pappus chain paradox

Are all rationally parametrized plane curves algebraic? How does one find their degree?

Can one prove existence of incommensurables without the Pythagorean theorem?

Finding covering system of congruences with prescribed moduli

Can existence of aleph one be proved without the power set axiom? [duplicate]

What is the dual space in the strong operator topology?

How many integer matrices have spectral radius bounded by a constant?

Can hyperreal numbers be studied 'naively', like surreal numbers?

Banach valued sequence spaces $\ell^p(X)$

Is there an intuitive reason why hippopede, the intersection curve of a sphere and a cylinder, is traced by composing two rotational motions?

Are order isomorphic real closed fields isomorphic?

Is there a formalisation of set theory where unions can be taken over some classes that are not a priori known to be sets?

Non-convex functions and their supporting hyperplanes