37 citations · 193 across the 39 of their papers we have counts for
41 papers
Peaks and peak-nestings on unit interval graphs
Per Alexandersson, Leonardo Saud Maia Leite
Unit interval graphs admit a classical Catalan encoding by area sequences, or equivalently by Dyck paths. We introduce a new statistic on these graphs, called peak-nesting, defined…
Real-rootedness and interlacing for parking functions and Chow polynomials
Per Alexandersson
We prove real-rootedness for the Chow polynomials of the noncrossing partition lattices by transferring tieless parking functions to finite-alphabet Smirnov words and applying an i…
New cases of the Strong Stanley Conjecture
Per Alexandersson, Ryan Mickler
We make progress towards understanding the structure of Littlewood-Richardson coefficients for products of Jack symmetric functions. Building on recent results of the s…
Restricted Birkhoff polytopes and Ehrhart period collapse
Per Alexandersson, Sam Hopkins, Gjergji Zaimi
We show that the polytopes obtained from the Birkhoff polytope by imposing additional inequalities restricting the "longest increasing subsequence" have Ehrhart quasi-polynomials w…
Linear first order differential operators and their Hutchinson-invariant sets
Per Alexandersson, Nils Hemmingsson, Dmitry Novikov +2
In this paper, we initiate the study of a new interrelation between linear ordinary differential operators and complex dynamics which we discuss in details in the simplest case of…
Pattern-avoidance and Fuss-Catalan numbers
Per Alexandersson, Samuel Asefa Fufa, Frether Getachew +1
We study a subset of permutations, where entries are restricted to having the same remainder as the index, modulo some integer . We show that when also imposing the class…
Peaks are preserved under run-sorting
Per Alexandersson, Olivia Nabawanda
We study a sorting procedure (run-sorting) on permutations, where runs are rearranged in lexicographic order. We describe a rather surprising bijection on permutations on length $n…
An involution on derangements preserving excedances and right-to-left minima
Per Alexandersson, Frether Getachew Kebede
We give a bijective proof of a result by R.~Mantaci and F.~Rakotondrajao from 2003, regarding even and odd derangement with a fixed number of excedances. We refine this result by a…
Refined Catalan and Narayana cyclic sieving
Per Alexandersson, Svante Linusson, Samu Potka +1
We prove several new instances of the cyclic sieving phenomenon (CSP) on Catalan objects of type A and type B. Moreover, we refine many of the known instances of the CSP on Catalan…
Promotion and cyclic sieving on families of SSYT
Per Alexandersson, Ezgi Kantarci Oğuz, Svante Linusson
We examine a few families of semistandard Young tableaux, for which we observe the cyclic sieving phenomenon under promotion. The first family we consider consists of stretched hoo…
Skew characters and cyclic sieving
Per Alexandersson, Stephan Pfannerer, Martin Rubey +1
In 2010, B. Rhoades proved that promotion together with the fake-degree polynomial associated with rectangular standard Young tableaux give an instance of the cyclic sieving phenom…
A combinatorial expansion of vertical-strip LLT polynomials in the basis of elementary symmetric functions
Per Alexandersson, Robin Sulzgruber
We give a new characterization of the vertical-strip LLT polynomials as the unique family of symmetric functions that satisfy certain combinatorial relations.…
NP-complete variants of some classical graph problems
Per Alexandersson
Some classical graph problems such as finding minimal spanning tree, shortest path or maximal flow can be done efficiently. We describe slight variations of such problems which are…
Symmetric polynomials in the symplectic alphabet and their expression via Dickson--Zhukovsky variables
Per Alexandersson, Luis Angel González-Serrano, Egor A. Maximenko +1
Given a symmetric polynomial in variables, there exists a unique symmetric polynomial in variables such that \[ P(x_1,\ldots,x_n,x_1^{-1},\ldots,x_n^{-1}) =Q(x_1+x…
LaserTank is NP-complete
Per Alexandersson, Petter Restadh
We show that the classical game LaserTank is -complete, even when the tank movement is restricted to a single column and the only blocks appearing on the board are mir…
Cyclic sieving, skew Macdonald polynomials and Schur positivity
Per Alexandersson, Joakim Uhlin
When is a partition, the specialized non-symmetric Macdonald polynomial is symmetric and related to a modified Hall--Littlewood polynomial. We show that whenever a…
Free action and cyclic sieving on skew semi-standard Young tableaux
Per Alexandersson
In this note, we provide a short proof of Theorem 3.3 in the paper titled \emph{Crystals, semistandard tableaux and cyclic sieving phenomenon}, by Y.-T.~Oh and E.~Park, which conce…
The cyclic sieving phenomenon on circular Dyck paths
Per Alexandersson, Svante Linusson, Samu Potka
We give a -enumeration of circular Dyck paths, which is a superset of the classical Dyck paths enumerated by the Catalan numbers. These objects have recently been studied by Ale…
LLT polynomials, elementary symmetric functions and melting lollipops
Per Alexandersson
We conjecture an explicit positive combinatorial formula for the expansion of unicellular LLT polynomials in the elementary symmetric basis. This is an analogue of the Shareshian-W…
Ehrhart positivity and Demazure characters
Per Alexandersson, Elie Alhajjar
Demazure characters, also known as key polynomials, generalize the classical Schur polynomials. In particular, when all variables are set equal to , these polynomials count the…
Some conjectures on the Schur expansion of Jack polynomials
Per Alexandersson, James Haglund, George Wang
We present positivity conjectures for the Schur expansion of Jack symmetric functions in two bases given by binomial coefficients. Partial results suggest that there are rich combi…
-partitions and -positivity
Per Alexandersson, Robin Sulzgruber
Using the combinatorics of -unimodal sets, we establish two new results in the theory of quasisymmetric functions. First, we obtain the expansion of the fundamental basis into q…
Enumeration of border-strip decompositions & Weil-Petersson volumes
Per Alexandersson, Linus Jordan
We describe an injection from border-strip decompositions of certain shapes to permutations. This allows us to provide enumeration results, as well as -analogues of enumeration…
On the Schur expansion of Jack polynomials
Per Alexandersson, James Haglund, George Wang
We present positivity conjectures for the Schur expansion of Jack symmetric functions in two bases given by binomial coefficients. Partial results suggest that there are rich combi…