48

Answers
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4
Left/right exact functor “in nature” which is not a right/left adjoint
2
semiring with zero- and nonzero test
1
Subtler than meets the eye: does x=y imply forall x forall y x=y?
4
Is it true that a set is countable if and only if there exists a Turing machine to enumerate all the elements in the set?
12
Simple adjective for “of the size of a proper class”?
1
Topos theory reference suitable for undergraduates
1
The effective topos - by Hyland
4
Game involving ‘asking questions about a real’
16
Is there a “disjoint union” sigma algebra?
12
Is it possible to construct (without choice, even?) a non-finitely-generated group with no proper non-finitely-generated subgroup?
5
Are the axioms for higher category-theory effectively computable?
28
Why are matrices ubiquitous but hypermatrices rare?
5
“classes” with no cardinality; “classes” with no equality notion
17
Sexy vacuity …
2
What’s the name of this flavor of n-category?
9
compact-open topology
6
Can we define geometric morphisms (between ETCS categories) elementarily?
9
Locally a topos
1
Rings with right inverses
6
Axiom of Replacement in Category Theory
2
Strict ordering on natural numbers
2
Need help understanding a topos theory proof (any topos generated by subobjects of 1 in whose subobject lattices are complete and Boolean satisfies AC)
2
The “skinnest” object
2
Maximal subcoalgebras of an $F+1$-coalgebra corresponding to an $F$-coalgebra
2
Do normal categories have pullbacks?
2
Pushout over a whole diagram
8
Indecomposable objects in a category
3
A functor that comes from a morphism in a bigger category
3
An elementary question about adjunctions between presheaf categories preserving pullbacks.
2
Equivalence of the two definitions of k-compactness/k-presentability
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