872 reputation
211
bio website hewwolff.org
location
age
visits member for 2 years, 3 months
seen Sep 16 at 19:11

Aug
11
answered Boundary connected sum of manifolds
Aug
10
accepted Why is the number of binary Lyndon words of length n usually divisible by 3?
Aug
10
comment Why is the number of binary Lyndon words of length n usually divisible by 3?
Very nice. To clarify, the second equation holds for all $n$, whether or not $n$ is a multiple of $3$. When $n$ is not a multiple of 3, we can use that equation to show that $a_n$ is a multiple of 3. So probably we should remove that line "If $n$ is not a multiple of 3" from the proof. Right?
Aug
3
asked Why is the number of binary Lyndon words of length n usually divisible by 3?
Jul
27
answered Lexicographical rank of a string with duplicate characters
Jul
27
answered How morphism of coverings induces morphism of automorphisms groups?
Jul
9
accepted Defining algebras over noncommutative rings
Jul
9
comment Defining algebras over noncommutative rings
I'm still trying to digest the monoidal category concept, but the list of axioms looks like what I need, thank you. Can we say more about what a "natural" monoidal structure is, and why the bimodules have one but the left modules don't?
Jul
3
comment Irrationality measure.
Can you post some of the proposed definitions so we can evaluate them?
Jul
2
awarded  Curious
Jun
29
revised Ideals of infinite product rings
incorporated feedback, expanded
Jun
28
comment Defining algebras over noncommutative rings
Thanks, fixed now.
Jun
28
revised Defining algebras over noncommutative rings
clarified: two-sided algebra has ring structure
Jun
28
asked Defining algebras over noncommutative rings
Jun
23
awarded  Yearling
Jun
7
comment Does a four-variable analog of the Hall-Witt identity exist?
We could formulate a more general question like this. A permutation $\pi$ on the set $S$ induces a permutation $F(\pi)$ on the free group $F(S)$. If $\pi$ is a cycle on a set $S$ with $n$ elements, what are the nontrivial $\gamma \in F(S)$ such that $\prod_{i=1}^n F(\pi)^i(\gamma) = 1$?
Jun
7
comment For what categories do category algebras exist?
I have some questions about the "Finitary incidence algebras" paper (from 2008, not the quasiorder one), but my e-mail to you bounced...
May
31
comment generalization of bijection proof
Maybe "partitions with no values divisible by $k$" and "partitions with no $k$-tuples of the same value", for $k > 2$? I think we need to know more about what kind of generalization you're looking for.
May
31
comment Column or row of a matrix?
I don't know of a standard notation for either the rows or columns, except maybe $M_{i*}$ and $M_{*j}$.
May
31
revised For what $x$ and $y$, the sum of the factorials of $x$ and $y$ equals 10 factorial?
tag was confusing