Peter LeFanu Lumsdaine's user avatar
Peter LeFanu Lumsdaine's user avatar
Peter LeFanu Lumsdaine's user avatar
Peter LeFanu Lumsdaine
  • Member for 14 years, 4 months
  • Last seen this week
61 votes
Accepted

Why should we believe in the axiom of regularity?

53 votes
Accepted

Are dagger categories truly evil?

48 votes

Interesting examples of vacuous / void entities

48 votes

Why do people say Gödel's sentence is true when it is true in some models but false in others?

47 votes

Why are matrices ubiquitous but hypermatrices rare?

42 votes

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

40 votes

Is a vector space naturally isomorphic to its dual?

36 votes

Are there categories whose internal hom is somewhat 'exotic'?

33 votes
Accepted

What "metatheory" did early set theory/logic researchers use to prove semantic results?

31 votes

Alternatives to the law of the excluded middle

29 votes

Abstract thought vs calculation

26 votes

Category theory and arithmetical identities

25 votes
Accepted

Is there a "disjoint union" sigma algebra?

25 votes

What is the most transparent, rigorous definition of the Univalence Axiom?

22 votes

The advantage of asymmetric objects

21 votes

Conceptual reason that monadic functors create limits?

20 votes

What is an explicit bijection in combinatorics?

19 votes

Formal definition of homotopy type theory

19 votes
Accepted

Missing axiom in the typed definition of a category?

19 votes
Accepted

Characterization of Kleisli adjunctions

19 votes
Accepted

Manifolds as Cauchy completed objects

19 votes
Accepted

What is known about the homotopy type of the classifier of subobjects of simplicial sets?

18 votes

Do combinatory logic bases need a function of 3 variables?

18 votes
Accepted

The role of univalence in the homotopy interpretation of type theory

17 votes
Accepted

Why are W-types called "W"?

17 votes

What is the endgoal of formalising mathematics?

16 votes

Constructively, is the unit of the “free abelian group” monad on sets injective?

16 votes
Accepted

Universal property of the set of injections in the category of sets

16 votes
Accepted

Why is $1$ not a dense sub-site in a group with the trivial Grothendieck topology?

15 votes

Most intriguing mathematical epigraphs

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