bio | website | Mail:firstname.lastnameatgmai… |
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location | Regensburg, Germany | |
age | ||
visits | member for | 4 years, 9 months |
seen | 20 mins ago | |
stats | profile views | 3,739 |
Jul 22 |
reviewed | Approve suggested edit on Solve this functional equation with respect to $f$ |
Jul 22 |
comment |
Proof correctness problem
There is a big list for question 2: mathoverflow.net/questions/35468/… |
Jul 20 |
reviewed | Approve suggested edit on Derivatives of infinite order |
Jul 19 |
awarded | Nice Question |
Jul 18 |
answered | Proof correctness problem |
Jul 17 |
comment |
Extremely messy proofs
Well, it's a paper of 30 pages. The relevant definitions and the actual proof are given on pages 4-19 which contain spacious diagrams and not too much text and additional examples on D-modules which can be skipped. Also it is so nicely written that you would rather want to last it longer :-) |
Jul 2 |
awarded | Curious |
Jul 1 |
awarded | Good Answer |
Jun 13 |
comment |
Merging / combining categories
@user52856 The combination of several structures is category theoretically best handled by looking at internal versions of the structures in question. Topological groups are group objects in Top. Group objects can be seen as product preserving functors from a small category, the Lawvere theory of groups, or from an even smaller product sketch. Combination of first order structures can be nicely described in the language of sketches: There is a tensor product of sketches such that a model of $A \otimes B$ is the same as a model of $A$ in the category of models of $B$... |
Jun 11 |
comment |
Merging / combining categories
An object in the pullback (strict or weak) in CAT of Top->Set<-Grp ist a set with a topology and a group structure. Nothing ensures that the structure maps of the group are continuous. Same with the required compatibilities in your other examples, e.g. if you try to present Rng as the pullback of Grp->Set<-Monoid you won't get a distributive law... |
May 29 |
comment |
What are the connections between pi and prime numbers?
It shows up when one considers the infinite prime together with the usual primes: mathoverflow.net/q/7656/733 |
May 24 |
reviewed | Approve suggested edit on Are all counterexamples of OEIS A226181 both Poulet numbers and Proth numbers? |
Mar 31 |
reviewed | Edit suggested edit on Is there a purely group-theoretic reformulation of an equivalence of subgroups? |
Mar 31 |
revised |
Is there a purely group-theoretic reformulation of an equivalence of subgroups?
I've added a link to a video of a conference of M. Izumi on this subject. |
Mar 31 |
comment |
Given a 2-category, is the hammock localization wrt the equivalences equivalent to taking the hom-wise nerve of the maximal subgroupoids?
@Zhen Lin : This helped me. Thanks again! |
Mar 31 |
comment |
Given a 2-category, is the hammock localization wrt the equivalences equivalent to taking the hom-wise nerve of the maximal subgroupoids?
Thank you for this example! You are right that the hammock localization cannot distinguish different 2-isomorphisms. Now if the hom-categories are preorders, the answer could still be affirmative. Any thoughts on this? |
Mar 30 |
asked | Given a 2-category, is the hammock localization wrt the equivalences equivalent to taking the hom-wise nerve of the maximal subgroupoids? |
Mar 30 |
awarded | Electorate |
Mar 20 |
awarded | Custodian |
Mar 20 |
reviewed | Approve suggested edit on Order homomorphism functions on $\omega_1$ |