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justin's user avatar
justin's user avatar
justin
  • Member for 10 years, 6 months
  • Last seen more than a week ago
59 votes
10 answers
7k views

Is it an abuse of language to say "*the* integers," "*the* rational numbers," or "*the* real numbers," etc.?

39 votes
7 answers
4k views

Do the axioms of set theory actually define the notion of a set?

33 votes
9 answers
4k views

Is formal truth in mathematical logic a generalization of everyday, intuitive truth?

18 votes
3 answers
2k views

Should this "definition" of set equality be an axiom?

14 votes
2 answers
2k views

How to prove that Gödel's Incompleteness Theorems apply to ZFC?

13 votes
1 answer
2k views

Are categories larger than classes?

12 votes
2 answers
2k views

Is it circular to define the Von Neumann universe using "sets"?

12 votes
3 answers
2k views

Is the "domain of discourse" in axiomatic set theory also a "set"?

11 votes
2 answers
3k views

Terry Tao's computational perspective on set theory

8 votes
0 answers
339 views

What system was Grothendieck working in when he introduced universes?

7 votes
0 answers
126 views

Does introducing a new type create a different extension, and is it still conservative?

7 votes
1 answer
191 views

Do mathematical objects have underlying types?

6 votes
1 answer
1k views

In $\mathbb Q_p$, proving every open ball is the disjoint union of more than one open ball

6 votes
3 answers
587 views

Confusion in proof that primes $p = 4k + 1$ are uniquely the sums of two squares

6 votes
3 answers
3k views

Eigenvalues of a Permutation?

6 votes
1 answer
2k views

Left-invariant vector fields on the circle $S^1$

5 votes
1 answer
811 views

Why do we write $df/dx$ instead of $df/dx(x)$?

4 votes
3 answers
15k views

Find all irreducible monic polynomials of degree 3 in $\mathbb Z/3\mathbb Z[x].$

4 votes
2 answers
418 views

If $\overline A\cap B = A\cap \overline B = \varnothing$, $A\cup B$ is disconnected.

4 votes
2 answers
1k views

Proving that the cross ratio is a Möbius transformation

4 votes
1 answer
533 views

Proving that extension by radicals implies solvable group

4 votes
1 answer
700 views

Smooth function on a manifold not dependent on coordinate chart

4 votes
2 answers
2k views

There exists no inner product on $\mathbb R^n$ that induces the maximum norm

4 votes
2 answers
521 views

The difference between a finite set and an ordered $n-$tuple? Proving the set of all finite subsets of a countable set is countable.

4 votes
4 answers
947 views

Do these theorems about power sets hold for the empty set?

4 votes
3 answers
3k views

Proving that cardinality of the reals = cardinality of $[0,1]$

4 votes
1 answer
1k views

Is every isomorphism of an algebraically closed field onto one of its subfields an automorphism?

3 votes
1 answer
252 views

Finding a subfield of $\mathbb R$ such that $e^2$ is of degree five over that subfield.

3 votes
3 answers
136 views

Does $\{(1-x)x^k\}$ converge uniformly on $[0,1]?$

3 votes
1 answer
199 views

How to compute associative binary operation on a finite set based on partial information?