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Enriched categories, topoi, abelian categories, monoidal categories, homological algebra.
15
votes
1
answer
521
views
What are the advantages of various "models" for the motivic stable homotopy category
People use several distinct models for the motivic stable homotopy category (so, there are some choices for the underlying category and a collection of available model structures). I would like to ask …
13
votes
Is there an additive functor between abelian categories which isn't exact in the middle?
As far as I remember, there is an important example of a functor that transforms mono- and epimorphisms into mono- and epimorphisms, respectively, but is not half-exact; this is the functor of interm …
13
votes
4
answers
2k
views
Localizing an arbitrary additive category
Under which conditions localizing an additive category by some class S of morphisms yields and additive category? It seems easy to define certain addition on morphisms if we fix their representatives …
12
votes
1
answer
403
views
Which statements and arguments of Hovey's "Model categories" fail without functorial factori...
I would like to study the homotopy theory of the category of pro-objects over a proper model category $M$. $Pro-M$ is endowed with the strict model structure; it seems that functorial functorizations …
11
votes
Accepted
Does the Grothendieck group depend on the embedding?
I think that the Grothendieck group DOES depend on A. Indeed, any additive category C could be embedded (by the Yoneda embedding) into the abelian category of contravariant additive functors from C to …
9
votes
1
answer
649
views
Objects of which Grothendieck abelian categories have elements?
The Freyd-Mitchell embedding theorem is a very useful tool for dealing with small abelian categories. However, it does not allow to use "elements" of objects of an abelian category $A$ in those statem …
8
votes
Accepted
When does a triangulated category have a heart?
A silly remark is that "trivial" $t$-structures always exist. You should probably say that you want a bounded or a non-degenerate $t$-structure. As far as I remember, non-zero negative $K$-groups of $ …
7
votes
2
answers
400
views
Properness of the category of modules over a spectrum (that represents algebraic cobordism o...
The abstract form of the question: let $C$ be a closed proper stable model category, $R$ is a ring object in it. Which conditions ensure that the category $R-mod$ is also proper?
Since weak equivalen …
7
votes
A toy example of a tensor triangulated category?
I think that the simplest example is $K(B)$ (the homotopy category of complexes; you can also consider $K^b(B)$) where $B$ is any tensor additive category. Certainly, this example is not independent f …
6
votes
0
answers
230
views
Nice references for injective model structures and Quillen functors between motivic homotopy...
It seems that for the injective model structures for the categories simplicial presheaves and simplicial Nisnevich sheaves (on the category of smooth varieties over a perfect field $k$) there exist co …
6
votes
1
answer
927
views
Does there exist a definition of equivalence of functors?
I have two functors $F_1,F_2$ from a category $C$ into two distinct categories $D_1,D_2$. I would like to say that $F_1$ and $F_2$ are equivalent if there exists a commutative square
$\require{AMScd}$ …
6
votes
0
answers
71
views
How would you say that transformations are isomorphic in the arrow category?
For functors $E,F,E',F':X\to Y$ I would like to say that transformations $\tau:E\to F$ and $\tau':E'\to F'$ are isomorphic if they are isomorpic in the arrow category of functors $X\to Y$, that is, t …
5
votes
1
answer
349
views
Which abelian categories possess an exact faithful functor into abelian groups that respects...
Let $A$ be an abelian category closed with respect to small coproducts (that is, and AB3 category). Which assumptions are sufficient to ensure the existence of an exact faithful functor from $A^{op}$ …
5
votes
0
answers
186
views
Which t-structure extend from subcategories of compact objects uniquely?
Let $T$ be a compactly generated triangulated category, that is, $T$ is closed with respect to small coproducts and equals its own smallest triangulated subcategory closed with respect to coproducts a …
5
votes
Accepted
Clarification on Hanamura's work on $t$ structure of triangulated category of mixed motives
1) I believe that the (Murre's) vanishing needed for Hanamura's argument is stronger than the BS conjecture.
2) There are certain standard conditions ensuring that a triangulated category is equivale …