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
1 vote

A conservative extension of Peano Arithmetic

5 votes

Does the simplex map to the cube?

8 votes
Accepted

Is the Rado graph the unique countable graph that has all finite graphs as induced subgraphs?

8 votes
Accepted

In what sense does the sentence $\operatorname{con}(\mathsf{PA})$ "say" that $\mathsf{PA}$ is consistent?

10 votes

Why are the source-target rules of composition always strictly defined?

3 votes
Accepted

Is there an $X$ and a non-surjective continuous function $f:X\to X$ such that $f\simeq {\rm id}_X$ but $f(X)$ and $X$ are not homotopy equivalent?

8 votes
Accepted

Epimorphisms of relations

6 votes
Accepted

Has this category of relational structures been studied?

7 votes
Accepted

Consistency in pure type systems

14 votes

Is End() a functor from the category of directed graphs to the category of monoids?

5 votes

Effective epimorphisms and 0-truncations (HTT, 7.2.1.14)

19 votes
Accepted

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

5 votes

Categorical equivalences vs. categories of simplices

12 votes
Accepted

Why isn't pullback-stability defined for individual colimits but for colimits with the same shape?

11 votes
Accepted

Why are enriched (co)ends defined like that?

3 votes
Accepted

Intuitive meaning of Giry monad's $\sigma$-algebra

3 votes

Original manuscript of Archimedes' cattle problem

3 votes

An application of ping-pong lemma

7 votes

An application of ping-pong lemma

5 votes

Book that shows a construction of ZFC with Calculus of Constructions

3 votes

two conjugate subgroups and one is a proper subset of the other? plus, a covering space interpretation.

7 votes

Books containing new results

6 votes
Accepted

On the definition of small categories in SGA4

7 votes
Accepted

Is the category of modules over a commutative ring the category of abelian objects in a topos?

16 votes
Accepted

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

13 votes

Are arbitrary nonempty intersections of principal filters principal?

19 votes
Accepted

Manifolds as Cauchy completed objects

16 votes
Accepted

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

7 votes

Can we write Tangled Type Theory without reference to type sequences?

22 votes

The advantage of asymmetric objects

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