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Olya Mandelshtam

Publications and source records attributed to Olya Mandelshtam.

26 records · Page 2Linked to original sources

arXiv2020

Combinatorics of the two-species ASEP and Koornwinder moments

In previous work, the first and third authors introduced staircase tableaux, which they used to give combinatorial formulas for the stationary distribution of the asymmetric simple exclusion process (ASEP) and for the moments of the Askey-Wilson weight function. The fact that the ASEP and Askey-Wilson moments are related at all is quite surprising, and is due to Uchiyama-Sasamoto-Wadati. The ASEP is a model of particles hopping on a one-dimensional lattice of N sites with open boundaries, particles can enter and exit at both left and right borders. It was introduced around 1970 and is cited as a model for both traffic flow and translation in protein synthesis. Meanwhile, the Askey-Wilson polynomials are a family of orthogonal polynomials in one variable, they sit at the top of the hierarchy of classical orthogonal polynomials. So we have the relationship ASEP -- staircase tableaux -- Askey-Wilson moments It is well-known that Askey-Wilson polynomials can be viewed as the one-variable case of the multivariate Koornwinder polynomials, also known as the Macdonald polynomials for the type BC root system. It is natural then to ask whether one can generalize the relationships among the ASEP, Askey-Wilson moments, and staircase tableaux, in such a way that Koornwinder moments replace Askey-Wilson moments. In a recent work, we demonstrated a close connection between Koornwinder moments and the two-species ASEP (a particle model involving two species of particles with different "weights"). In this article we introduce rhombic staircase tableaux, and show that we have the relationship 2-species ASEP -- rhombic staircase tableaux -- Koornwinder moments In particular, we give formulas for the steady state distribution of the two-species ASEP and for Koornwinder moments, in terms of rhombic staircase tableaux.

math.CO↗

arXiv2020

Tableaux combinatorics of the two-species PASEP

We study a two-species PASEP, in which there are two types of particles, "heavy" and "light," hopping right and left on a one-dimensional lattice of $n$ cells with open boundaries. In this process, only the "heavy" particles can enter on the left of the lattice and exit from the right of the lattice. In the bulk, any transition where a heavier particle type swaps places with an adjacent lighter particle type is possible. We generalize combinatorial results of Corteel and Williams for the ordinary PASEP by defining a combinatorial object which we call a rhombic alternative tableau that gives a combinatorial formula for the stationary probabilities for the states of this two-species PASEP.

math.CO↗

arXiv2019

Compact formulas for Macdonald polynomials and quasisymmetric Macdonald polynomials

We present several new and compact formulas for the modified and integral form of the Macdonald polynomials, building on the compact "multiline queue" formula for Macdonald polynomials due to Corteel, Mandelshtam and Williams. We also introduce a new quasisymmetric analogue of Macdonald polynomials. These quasisymmetric Macdonald polynomials refine the (symmetric) Macdonald polynomials and specialize at $q=t=0$ to the quasisymmetric Schur polynomials defined by Haglund, Luoto, Mason, and van Willigenburg. This is an extended abstract.

math.CO↗

arXiv2019

Toric tableaux and the inhomogeneous two-species TASEP on a ring

The inhomogeneous two-species TASEP on a ring is an exclusion process that describes particles of different species hopping clockwise on a ring with parameters giving the hopping rates for different species. We introduce a combinatorial object that we call \emph{toric rhombic alternative tableaux}, which are certain fillings of tableaux on a triangular lattice tiled with rhombi, and are in bijection with the well-studied \emph{multiline queues} of Ferrari and Martin. Using the tableaux, we obtain a formula for the stationary probabilities of this TASEP, which specializes to results of Ayyer and Linusson. We obtain, in addition, an explicit determinantal formula for these probabilities, and define a Markov chain on the tableaux that projects to the two-species TASEP on a ring.

math.CO↗

arXiv2016

Rhombic alternative tableaux and assemblées of permutations

In this paper, we introduce the rhombic alternative tableaux, whose weight generating functions provide combinatorial formulae to compute the steady state probabilities of the two-species ASEP. In the ASEP, there are two species of particles, one heavy and one light, hopping right and left on a one-dimensional finite lattice with open boundaries. Parameters $α$, $β$, and $q$ describe the hopping probabilities. The rhombic alternative tableaux are enumerated by the Lah numbers, which also enumerate certain assemblées of permutations. We describe a bijection between the rhombic alternative tableaux and these assemblées. We also provide an insertion algorithm that gives a weight generating function for the assemblées. Combined, these results give a bijective proof for the weight generating function for the rhombic alternative tableaux, which is also the partition function of the two-species ASEP at $q=1$.

math.CO↗

arXiv2015

LGV proof of a determinantal theorem for TASEP probabilities

The Totally Asymmetric Simple Exclusion Process (TASEP) is a non-equilibrium particle model on a finite one-dimensional lattice with open boundaries. In our earlier paper, we obtained a determinantal formula that computes the steady state probabilities of this process by the enumeration of "Catalan alternative tableaux", which are certain fillings of Young diagrams. Here, we present a new, more illuminating bijective proof of this determinantal formula using the Lindström-Gessel-Viennot Lemma.

math.CO↗

arXiv2015

Multi-Catalan Tableaux and the Two-Species TASEP

The goal of this paper is to provide a combinatorial expression for the steady state probabilities of the two-species PASEP. In this model, there are two species of particles, one "heavy" and one "light", on a one-dimensional finite lattice with open boundaries. Both particles can swap places with adjacent holes to the right and left at rates 1 and $q$. Moreover, when the heavy and light particles are adjacent to each other, they can swap places as if the light particle were a hole. Additionally, the heavy particle can hop in and out at the boundary of the lattice. Our main result is a combinatorial interpretation for the stationary distribution at $q=0$ in terms of certain multi-Catalan tableaux. We provide an explicit determinantal formula for the steady state probabilities, as well as some general enumerative results for this case. We also describe a Markov process on these tableaux that projects to the two-species PASEP, and thus directly explains the connection between the two. Finally, we give a conjecture that extends our formula for the stationary distribution to the $q=1$ case, using certain two-species alternative tableau.

math.CO↗

arXiv2015

A Determinantal Formula for Catalan Tableaux and TASEP Probabilities

We present a determinantal formula for the steady state probability of each state of the TASEP (Totally Asymmetric Simple Exclusion Process) with open boundaries, a 1D particle model that has been studied extensively and displays rich combinatorial structure. These steady state probabilities are computed by the enumeration of Catalan tableaux, which are certain Young diagrams filled with $α$'s and $β$'s that satisfy some conditions on the rows and columns. We construct a bijection from the Catalan tableaux to weighted lattice paths on a Young diagram, and from this we enumerate the paths with a determinantal formula, building upon a formula of Narayana that counts unweighted lattice paths on a Young diagram. Finally, we provide a formula for the enumeration of Catalan tableaux that satisfy a given condition on the rows, which corresponds to the steady state probability that in the TASEP on a lattice with $n$ sites, precisely $k$ of the sites are occupied by particles. This formula is an $α /\ β$ generalization of the Narayana numbers.

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