Will Brian's user avatar
Will Brian's user avatar
Will Brian's user avatar
Will Brian
  • Member for 7 years, 11 months
  • Last seen this week
122 votes

Tweetable Mathematics

66 votes
Accepted

Bijection from the plane to itself that sends circles to squares

45 votes

When can one continuously prescribe a unit vector orthogonal to a given orthonormal system?

42 votes

Which popular games have been studied mathematically?

40 votes
Accepted

A topology on $\Bbb R$ where the compact sets are precisely the countable sets

38 votes
Accepted

Are all free ultrafilters 'the same' in some sense?

29 votes

Proofs where higher dimension or cardinality actually enabled much simpler proof?

27 votes
Accepted

Does the axiom of choice follow from the statement "Every simple undirected graph is either connected, or its complement is connected"?

25 votes

Is it possible to define higher cardinal arithmetics

25 votes

Can you partition the sphere into orthonormal bases?

23 votes
Accepted

Can random variables that almost surely solve equations be repaired to surely solve these equations?

23 votes
Accepted

Continuous images of $\beta \mathbb{N} \setminus\mathbb{N}$

22 votes

Unnecessary uses of the Continuum Hypothesis

20 votes
Accepted

Can an injective $f: \Bbb{R}^m \to \Bbb{R}^n$ have a closed graph for $m>n$?

19 votes
Accepted

Is $[0,1]$ a disjoint union of $\aleph_1$ compact subsets with empty interior?

17 votes

Continuous bijections vs. Homeomorphisms

17 votes
Accepted

Is there a known condition for partial sums of a decreasing positive sequence to take all values up to the total sum?

17 votes

Is every function $f: \mathbb R \to \mathbb R$ differentiable at at least one point when restricted to some everywhere dense subset of $\mathbb R$?

17 votes
Accepted

A metric characterization of the real line

16 votes
Accepted

Ultrafilter subtraction and "zero"

16 votes

Necessary use of large cardinals in mathematics

15 votes
Accepted

Can two-point sets be Borel?

15 votes
Accepted

Does the class of Hausdorff spaces have a shared "Coordinate space"?

14 votes
Accepted

On the Large Cardinal Strength of Normal Moore Space Conjecture

14 votes
Accepted

How “disconnected” can a continuum be?

14 votes
Accepted

Partitions of the real line into Borel subsets

13 votes

Fair cutting of the plane with lines

13 votes
Accepted

Graphs that are not $\mathbb{R}^2$-realizable

13 votes
Accepted

Packing obtuse vectors in $\mathbb{R}^d$

13 votes

Is there a subset of the plane that meets every line in two open intervals?

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