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Lord_Farin
  • Member for 11 years, 5 months
  • Last seen more than 1 year ago
16 votes
2 answers
1k views

Proving existence of a surjection $2^{\aleph_0} \to \aleph_1$ without AC

14 votes
1 answer
2k views

Every net has an ultranet as subnet: direct proof

13 votes
2 answers
950 views

Motivating the compact-open topology

12 votes
2 answers
2k views

Countable ordinals are embeddable in the rationals $\Bbb Q$ -- proofs and their use of AC

9 votes
1 answer
832 views

Proving the $\Delta$ lemma using Fodor's Theorem

7 votes
1 answer
781 views

Factoring polynomials with prime discriminant

7 votes
1 answer
248 views

Instance of Continuum Hypothesis implying cardinal inequality

5 votes
1 answer
645 views

Showing that the sheaf-functor $\epsilon: \tilde{\sf C} \to \tilde{\tilde{\sf C}}$ is an equivalence

4 votes
1 answer
84 views

Is it impossible to recover multiplication from the division lattice categorically?

3 votes
0 answers
1k views

How many ternary functionally complete connectives are there?

2 votes
0 answers
118 views

Checking continuity for homotopy on glued space -- is it necessary?

2 votes
1 answer
708 views

A proof about $\sigma$-algebras via transfinite induction

2 votes
2 answers
110 views

Bases for $\Bbb Z^n$ containing a given vector