bio  website  

location  Münster, Germany  
age  27  
visits  member for  5 years, 5 months 
seen  16 hours ago  
stats  profile views  37,351 
I am interested in the interactions between algebraic geometry and category theory. More specifically, I "model" algebraic geometry on cocomplete symmetric monoidal categories.
Here is a link to my PhD thesis. Comments are welcome.
Email: [my last name] [at] unimuenster.de
16h

comment 
Simple examples for the use of spectral sequences
I wish I could do these calculations in my head! 
May 24 
awarded  Favorite Question 
May 17 
awarded  Popular Question 
May 14 
awarded  Good Answer 
May 6 
asked  Kan extensions in the $2$category of monoidal categories 
May 2 
awarded  Popular Question 
Apr 30 
revised 
Should the formula for the inverse of a 2x2 matrix be obvious?
deleted 10 characters in body 
Apr 30 
accepted  Exact sequences of pointed sets  two definitions 
Apr 30 
revised 
Exact sequences of pointed sets  two definitions
added 70 characters in body 
Apr 29 
awarded  Popular Question 
Apr 28 
asked  Exact sequences of pointed sets  two definitions 
Apr 23 
comment 
Awfully sophisticated proof for simple facts
@Vectornaut: Why? 
Apr 20 
comment 
How would set theory research be affected by using ETCS instead of ZFC?
Couldn't we just say that the notions of transitive sets and wellfounded relations are more or less restricted to "material set theories" (as defined at the nlab)? And then ETCS and SEAR, as structural set theories, will have some problems with these notions. Still, structural set theories seem to capture what's going on in all fields of mathematics except for what is called "set theory", but which is really "material set theory". Right? 
Apr 20 
comment 
How would set theory research be affected by using ETCS instead of ZFC?
@Todd Trimble: Has SEAR been published in a journal or a book? 
Apr 18 
comment 
(co)limits in the category of diffeological spaces vs. category of smooth manifolds
@user59001: Why do you post this on mathoverflow after having received an answer on math.stackexchange? Could you please at least leave a comment there? 
Apr 16 
awarded  Popular Question 
Apr 14 
comment 
Sexy vacuity …
Oups, I meant continuous functions into discrete spaces, aka locally constant functions. 
Apr 8 
comment 
Do homsets really live in the category Set?
I just wanted to remark that I've posted an answer on the math.SE version of this question. 
Mar 30 
comment 
Why is a topology made up of 'open' sets?
"the category of topological spaces is equivalent to the category of relational algebras for the ultrafilter monad."  they are isomorphic, I guess. 
Mar 30 
comment 
Why is a topology made up of 'open' sets?
This great answer reminds me of several "unbiased" or "monadic" definitions of structures such as monoids or monoidal categories. The definition of a monoid "should" really introduce $n$fold products for $n \in \mathbb{N}$, not just $0$fold and $2$fold products. Curiously, the monoid axioms are quite easy to state for $n$fold products; this is even more true for the coherence axioms in the definition of a monoidal category via $n$fold tensor products. 