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Trebor
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33 votes
1 answer
896 views

Is there an elementary expression for every real sequence?

7 votes
0 answers
106 views

Why are there so many concepts beginning with "mod-"?

6 votes
1 answer
118 views

On a peculiar operation on polynomials

6 votes
1 answer
112 views

How can we quickly verify naturality?

5 votes
1 answer
120 views

Axiom of choice for lifting infinitary operation

4 votes
1 answer
170 views

Prove that a surreal number is born in a finite stage if and only if it is of the form $\frac m{2^n}$.

4 votes
2 answers
92 views

Functionally complete set of a particular trivalued logic

3 votes
1 answer
128 views

What is the automorphism group of $\mathbb R / \mathbb Z$ as a group?

3 votes
1 answer
248 views

Understanding a particular method of solving generalized version of Pell's equation

3 votes
1 answer
330 views

What are all the functions that preserve the cross ratio?

3 votes
1 answer
54 views

Connectedness of $\{(x,y,z)\ : \ x,y,z \in \mathbb Z, \gcd(x,y,z) = 1\}$ under the relation $\vec u \cdot \vec v = 1$

2 votes
2 answers
210 views

Proving that no positive integer solutions exist for $x^2 = y^{119}+1$

2 votes
1 answer
813 views

Proving $\vdash \neg \neg P \to P$ (double negation elimination) in first order logic, preferrably without deduction theorem

2 votes
2 answers
84 views

Do type constructors have type themselves?

2 votes
1 answer
269 views

Why should we adopt the cumulative universe convention?

2 votes
2 answers
65 views

Choosing a "good" partition given that non-null measurable sets have a "good" subset with positive measure

1 vote
0 answers
53 views

Visually suggestive way to present a finite group

1 vote
1 answer
315 views

Why is there only one point at infinity in the extended complex plane, but one in each direction in the real projective plane?

1 vote
0 answers
117 views

Cohomology of Hawaiian earring, Hatcher exercise

1 vote
1 answer
91 views

When can non-trivial roots of unity be partitioned such that product of their sums is an integer?

0 votes
0 answers
38 views

Zariski opens of an affine space and (po)sites

0 votes
0 answers
55 views

If a set of polynomial equations with integral coefficients has a complex solution, does it have a solution $\bmod p$?