bio  website  mit.edu/~darij/www 

location  Karlsruhe (home), Munich (until summer 2011), Cambridge/MA (2011)  
age  26  
visits  member for  5 years, 5 months 
seen  14 mins ago  
stats  profile views  12,395 
I'm just here for asking stupid questions.
1d

comment 
Most harmful heuristic?
Both of your points are true. It is a good idea to bring up the Jordan normal form before the theory of modules over a PID, but it is not at all necessary to teach its proof and the algorithm before the general case of a PID. 
May 20 
revised 
Newton polyhedron and product of ideals
added 4 characters in body; edited title 
May 18 
awarded  Necromancer 
May 16 
awarded  Favorite Question 
May 11 
reviewed  Leave Open Fixed point theorem in ordered spaces 
May 11 
reviewed  Leave Open Why is the evaluation map of sheaves injective 
May 11 
reviewed  Close Orbits of a cyclic group on the powerset 
May 11 
reviewed  Leave Open Question about Eigenvalues of group elements 
May 11 
reviewed  Leave Open Representations of Hamilton's real/complex quaternions algebra 
May 11 
revised 
What are some examples of colorful language in serious mathematics papers?
added 55 characters in body 
May 6 
comment 
Reference for Hopf algebra applications to Feynman diagrams
Alessandra Frabetti is a name that comes to my mind, but I am as far from understanding this subject as one can be. 
May 5 
comment 
Combinatorial polynomials from general diagram fillings?
These $P$partition enumerators and their generalizations are the subject of several papers by Malvenuto and Reutenauer, e.g., arXiv:1407.0476v2, arXiv:0905.3508v1, and "Plethysm and conjugation of quasisymmetric functions". One thing that generalizes very well from the classical case are formulas for the coproduct and the antipode (in the Hopf algebra $\operatorname{QSym}$). I am trying to write an expository paper about this for a year now... 
May 5 
comment 
What are some examples of interesting uses of the theory of combinatorial species?
Very nice  worth an edit of the post, I guess. 
May 4 
reviewed  Approve How to prove the following determinant identity? 
May 4 
comment 
scalar multiple of Young symmetrizer
Ah! You want the general $n_x$. Sorry. 
May 4 
comment 
scalar multiple of Young symmetrizer
The $n_\lambda$ is the product of the hook lengths of $\lambda$. Combine Lemma 4.42 with Theorem 4.53 in arxiv.org/abs/0901.0827v5. (That said, I hope Fulton/Harris also have a proof of this somewhere.) 
May 3 
comment 
What are some examples of interesting uses of the theory of combinatorial species?
Does your recent arXiv preprint with Westbury warrant an update of this post? 
Apr 30 
awarded  Necromancer 
Apr 30 
comment 
Antisymmetrization of the Hochschild cocycle
You are right about homology vs. cohomology, though  these are different problems. Sorry! 
Apr 29 
comment 
Antisymmetrization of the Hochschild cocycle
$b^2 = 0$ does not hold with the wrong signs; check the case $n = 0$. 