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Trebor
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33 votes
1 answer
889 views

Is there an elementary expression for every real sequence?

7 votes
0 answers
105 views

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

6 votes
1 answer
117 views

On a peculiar operation on polynomials

6 votes
1 answer
107 views

How can we quickly verify naturality?

5 votes
1 answer
119 views

Axiom of choice for lifting infinitary operation

4 votes
1 answer
167 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
89 views

Functionally complete set of a particular trivalued logic

3 votes
1 answer
126 views

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

3 votes
1 answer
244 views

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

3 votes
1 answer
320 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
205 views

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

2 votes
1 answer
790 views

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

2 votes
2 answers
78 views

Do type constructors have type themselves?

2 votes
1 answer
264 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
52 views

Visually suggestive way to present a finite group

1 vote
1 answer
310 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
112 views

Cohomology of Hawaiian earring, Hatcher exercise

0 votes
0 answers
54 views

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