Mastodawn

So pleased to have posted a preprint with Amanda Burcroff this week, on eventual sign coherence for quiver mutation. http://arxiv.org/abs/2605.12865

I'm especially happy to now be a scholar of brogs https://www.xenoserieswiki.org/wiki/Brog
#combinatorics #xenoblade #quivers #clusteralgebras

Eventual sign coherence

The sign coherence of $c$-vectors is one of the fundamental theorems of cluster algebras with principal coefficients. In 2019, Gekhtman and Nakanishi posed the asymptotic sign coherence conjecture for arbitrary cluster algebras of geometric type, which says sign coherence should eventually hold in any sufficiently generic infinite mutation sequence. We prove that their conjecture holds almost always for skew-symmetric cluster algebras of arbitrary rank. That is, we prove that with probability $1$, the sequence of $c$-vectors obtained by random mutation of an arbitrary quiver eventually becomes sign-coherent. Our results also establish the conjecture in full generality for many families of quivers by studying a new class of brog quivers.

arXiv.org

Jan Marthedal Rasmussen May 9

Generating All Permutations http://janmr.com/posts/generating-all-permutations/ #combinatorics #algorithms #python #rust

janmr.com | Generating All Permutations

janmr.com

Paul Balduf May 4

Registration is open for the 2026 colloquia in #combinatorics on 13+14 of May, 2026, in London.
#scientificConference #mathematics
https://2dcic.github.io/

kipriyanovich Apr 27

Alright, future engineers!
**Combinations:** Ways to *choose* items from a set where the order *doesn't* matter.
Ex: Picking 3 teammates from 5 friends: `C(5,3) = 10` ways.
Pro-Tip: If swapping items doesn't create a new outcome, it's a combination!
#DiscreteMath #Combinatorics #STEM #StudyNotes

kipriyanovich Apr 25

Alright, future engineers!
**Combinations**: ways to choose items where order *doesn't* matter.
Ex: Choose 2 teammates from 5 friends: `C(5,2) = 5!/(2!3!) = 10` ways.
Pro-Tip: Think 'choosing a committee' – the group is what matters, not selection order!
#Probability #Combinatorics #STEM #StudyNotes

kipriyanovich Apr 24

Alright, future engineers!

**Combinations**: ways to choose items where order *doesn't* matter.
Ex: Picking 3 committee members from 5 people: C(5,3) = 10 ways.
Pro-Tip: Think 'selecting ingredients for a soup' – the order you add them doesn't change the final soup!

#Combinatorics #DiscreteMath #STEM #StudyNotes

kipriyanovich Apr 24

Alright, future engineers!

**Permutations**: ways to arrange items where order matters.
Ex: Arranging 3 books (A,B,C) is 3! = 6 ways.
Pro-Tip: Think 'President, VP, Secretary' - roles are distinct!

#Probability #Combinatorics #STEM #StudyNotes

kipriyanovich Apr 20

Alright, future engineers!
**Combinations** count selections where order *doesn't* matter. Ex: Picking 3 teammates from 10. Formula: C(n,r) = n! / (r!(n-r)!). Pro-Tip: If reordering items yields the *same* group, it's a combination!
#Probability #Combinatorics #STEM #StudyNotes

kipriyanovich Apr 12

Alright, future engineers!
A **Combination** is a selection of items where order *doesn't* matter. Ex: Choosing 3 people for a committee from 10. `C(N,K) = N!/(K!(N-K)!)`. Pro-Tip: Use for groups, not sequences!
#Combinatorics #DiscreteMath #STEM #StudyNotes

Paul Balduf Apr 10

Registration is open for the 31st British Combinatorial Conference in Cardiff in Early July. Besides the plenary talks, there are minisymposia on various topics of #combinatorics and related areas of #mathematics , participants can submit abstracts for 20-min contributed talks.
Registration is cheaper before 17 May.
https://sites.google.com/view/bcc2026/home

31st BCC 2026

The British Combinatorial Conference is held every two years at a UK university. It features nine renowned plenary speakers, showcasing the full range of combinatorial mathematics, alongside several mini-symposia on more specialised topics, and contributed talks. The registration for the 31st