Andreas Blass's user avatar
Andreas Blass's user avatar
Andreas Blass's user avatar
Andreas Blass
  • Member for 13 years, 11 months
  • Last seen this week
30 votes

Mathematicians who made important contributions outside their own field?

30 votes

About the axiom of choice, the fundamental theorem of algebra, and real numbers

30 votes

Theorems first published in textbooks?

30 votes

Finite axiom of choice: how do you prove it from just ZF?

30 votes
Accepted

Direct product of filters

30 votes

Is PA consistent? do we know it?

29 votes

How many orders of infinity are there?

29 votes

Fraktur symbols for Lie algebras

29 votes

How to explain the concentration-of-measure phenomenon intuitively?

28 votes
Accepted

Unprovable statements S where the only way to prove S is to assume S

28 votes
Accepted

Are proper classes objects?

27 votes

Why is the fibered coproduct of affine schemes not affine?

27 votes
Accepted

Bourbaki's epsilon-calculus notation

27 votes

Are there more connected or disconnected graphs on $n$ vertices?

27 votes

Who discovered the surreals?

27 votes

Is there a general theory of "compactification"?

26 votes
Accepted

Why is there a need for ordinal analysis?

26 votes

Nonessential use of large cardinals

26 votes
Accepted

About the proof of the proposition "there exists irrational numbers a, b such that a^b is rational"

26 votes

Proving Independence of Axioms by Exhibiting Models Which Don't Satisfy Our Intuition

26 votes

Why hasn't mereology succeeded as an alternative to set theory?

26 votes

Can infinity shorten proofs a lot?

25 votes

How many models of Peano arithmetic are isomorphic to the standard model and how many models of Peano arithmetic are non-standard?

24 votes
Accepted

Morse-Kelley set theory consistency strength

24 votes

How to introduce notions of flat, projective and free modules?

23 votes

What interesting/nontrivial results in Algebraic geometry require the existence of universes?

23 votes
Accepted

Partitioning $\mathbb{R}$ into $\aleph_1$ Borel sets

23 votes
Accepted

Is a random subset of the real numbers non-measurable? Is the set of measurable sets measurable?

23 votes

What's a non-abelian totally ordered group?

23 votes

Is there a useful limit or co-limit of a diagram that has only a single object?

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