scholarly journals An algorithm which generates linear extensions for a non-simply-laced d-complete poset with uniform probability

2012 ◽  
Vol DMTCS Proceedings vol. AR,... (Proceedings) ◽  
Author(s):  
Kento Nakada
Keyword(s):  
Linear Extensions ◽  
Uniform Probability ◽  
International Audience

International audience \textbfAbstract. The purpose of this paper is to present an algorithm which generates linear extensions for a non-simply-laced d-complete poset with uniform probability. ≠wline Le but de ce papier est prèsenter un algorithme qui produit des extensions linèaires pour une non-simply-laced d-complete poset avec probabilitè constante.

scholarly journals An algorithm which generates linear extensions for a generalized Young diagram with uniform probability

2010 ◽  
Vol DMTCS Proceedings vol. AN,... (Proceedings) ◽  
Author(s):  
Kento Nakada ◽  
Shuji Okamura
Keyword(s):  
Young Diagram ◽  
Linear Extensions ◽  
Reduced Decompositions ◽  
Uniform Probability ◽  
Hook Formula ◽  
International Audience

International audience The purpose of this paper is to present an algorithm which generates linear extensions for a generalized Young diagram, in the sense of D. Peterson and R. A. Proctor, with uniform probability. This gives a proof of a D. Peterson's hook formula for the number of reduced decompositions of a given minuscule elements. \par Le but de ce papier est présenter un algorithme qui produit des extensions linéaires pour un Young diagramme généralisé dans le sens de D. Peterson et R. A. Proctor, avec probabilité constante. Cela donne une preuve de la hook formule d'un D. Peterson pour le nombre de décompositions réduites d'un éléments minuscules donné.

scholarly journals Operations on partially ordered sets and rational identities of type A

2013 ◽  
Vol Vol. 15 no. 2 (Combinatorics) ◽  
Author(s):  
Adrien Boussicault
Keyword(s):  
Partially Ordered Sets ◽  
Rational Functions ◽  
Hasse Diagram ◽  
Linear Extensions ◽  
Ordered Sets ◽  
Closed Expression ◽  
Schubert Polynomials ◽  
Special Cases ◽  
The Family ◽  
International Audience

Combinatorics International audience We consider the family of rational functions ψw= ∏( xwi - xwi+1 )-1 indexed by words with no repetition. We study the combinatorics of the sums ΨP of the functions ψw when w describes the linear extensions of a given poset P. In particular, we point out the connexions between some transformations on posets and elementary operations on the fraction ΨP. We prove that the denominator of ΨP has a closed expression in terms of the Hasse diagram of P, and we compute its numerator in some special cases. We show that the computation of ΨP can be reduced to the case of bipartite posets. Finally, we compute the numerators associated to some special bipartite graphs as Schubert polynomials.

scholarly journals Bijactions in Cataland

2014 ◽  
Vol DMTCS Proceedings vol. AT,... (Proceedings) ◽  
Author(s):  
Nathan Williams
Keyword(s):  
Linear Extensions ◽  
International Audience ◽  
Order Ideals ◽  
Reduced Words

International audience In this abstract, I will survey the story of two enumerative miracles that relate certain Coxeter-theoretic objects and other poset-theoretic objects. The first miracle relates reduced words and linear extensions, while the second may be thought of as relating group elements and order ideals. The purpose of this abstract is to use a conjecture from my thesis to present both miracles in the same light. Dans ce résumé, j’étudie l’histoire de deux miracles énumératifs qui relient certains objets de la théorie de Coxeter et d’autres objets de la théorie des posets. Le premier miracle relie des mots réduits et des extensions linéaires, tandis que le second relie des éléments du groupe et des idéaux d’ordre. Le but de ce résumé est d’utiliser une conjecture de ma thèse afin de présenter les deux miracles sous la même lumière.

scholarly journals Promotion and Rowmotion

2012 ◽  
Vol DMTCS Proceedings vol. AR,... (Proceedings) ◽  
Author(s):  
Jessica Striker ◽  
Nathan Williams
Keyword(s):  
Recent Work ◽  
Linear Extensions ◽  
Alternating Sign Matrices ◽  
Plane Partitions ◽  
International Audience ◽  
Order Ideals

International audience We present an equivariant bijection between two actions—promotion and rowmotion—on order ideals in certain posets. This bijection simultaneously generalizes a result of R. Stanley concerning promotion on the linear extensions of two disjoint chains and certain cases of recent work of D. Armstrong, C. Stump, and H. Thomas on noncrossing and nonnesting partitions. We apply this bijection to several classes of posets, obtaining equivariant bijections to various known objects under rotation. We extend the same idea to give an equivariant bijection between alternating sign matrices under rowmotion and under B. Wieland's gyration. Lastly, we define two actions with related orders on alternating sign matrices and totally symmetric self-complementary plane partitions. Nous prèsentons une bijection èquivariante entre deux actions—promotion et rowmotion—sur les idèaux d'ordre dans certaines posets. Cette bijection gènèralise simultanèment un rèsultat de R. Stanley concernant la promotion sur les extensions linèaire de deux cha\^ınes disjointes et certains cas des travaux rècents de D. Armstrong, C. Stump, et H. Thomas sur les partitions noncroisèes et nonembo\^ıtèes. Nous appliquons cette bijection à plusieurs classes de posets pour obtenir des bijections èquivariantes a des diffèrents objets connus sous la rotation. Nous gènèralisons la même idèe pour donnè une bijection èquivariante entre les matrices à signes alternants sous rowmotion et sous la gyration de B. Wieland. Finalement, nous dèfinissons deux actions avec des ordres similaires sur les matrices à signes alternants et les partitions plane totalement symètriques et autocomplèmentaires.

scholarly journals A combinatorial model for exceptional sequences in type A

2015 ◽  
Vol DMTCS Proceedings, 27th... (Proceedings) ◽  
Author(s):  
Alexander Garver ◽  
Jacob P. Matherne
Keyword(s):  
Type A ◽  
Linear Extensions ◽  
Quiver Representations ◽  
Noncrossing Partitions ◽  
Labeled Trees ◽  
Combinatorial Model ◽  
International Audience ◽  
Exceptional Sequences ◽  
Nous Utilisons

International audience Exceptional sequences are certain ordered sequences of quiver representations. We use noncrossing edge-labeled trees in a disk with boundary vertices (expanding on T. Araya’s work) to classify exceptional sequences of representations of $Q$, the linearly ordered quiver with $n$ vertices. We also show how to use variations of this model to classify $c$-matrices of $Q$, to interpret exceptional sequences as linear extensions, and to give a simple bijection between exceptional sequences and certain chains in the lattice of noncrossing partitions. In the case of $c$-matrices, we also give an interpretation of $c$-matrix mutation in terms of our noncrossing trees with directed edges. Les suites exceptionnelles sont certaines suites ordonnées de représentations de carquois. Nous utilisons des arbres aux arêtes étiquetés et aux sommets dans le bord d’un disque (expansion sur le travail de T. Araya) pour classifier les suites exceptionnelles de représentations du carquois linéairement ordonné à $n$ sommets. Nous exploitons des variations de ce modèle pour classifier les $c$-matrices dudit carquois, pour interpréter les suites exceptionnelles comme des extensions linéaires, et pour donner une bijection élémentaire entre les suites exceptionnelles et certaines chaînes dans le réseau des partitions sans croisement. Dans le cas des $c$-matrices, nous donnons également une interprétation de la mutation des $c$-matrices en termes des arbres sans croisement aux arêtes orientés.

scholarly journals A phase transition in the distribution of the length of integer partitions

2012 ◽  
Vol DMTCS Proceedings vol. AQ,... (Proceedings) ◽  
Author(s):  
Dimbinaina Ralaivaosaona
Keyword(s):  
Phase Transition ◽  
Positive Integer ◽  
Gaussian Distribution ◽  
Gumbel Distribution ◽  
Limiting Distribution ◽  
Integer Partitions ◽  
Random Partition ◽  
Uniform Probability ◽  
International Audience

International audience We assign a uniform probability to the set consisting of partitions of a positive integer $n$ such that the multiplicity of each summand is less than a given number $d$ and we study the limiting distribution of the number of summands in a random partition. It is known from a result by Erdős and Lehner published in 1941 that the distributions of the length in random restricted $(d=2)$ and random unrestricted $(d \geq n+1)$ partitions behave very differently. In this paper we show that as the bound $d$ increases we observe a phase transition in which the distribution goes from the Gaussian distribution of the restricted case to the Gumbel distribution of the unrestricted case.

scholarly journals Graph Orientations and Linear Extensions.

2014 ◽  
Vol DMTCS Proceedings vol. AT,... (Proceedings) ◽  
Author(s):  
Benjamin Iriarte
Keyword(s):  
Partial Order ◽  
Simple Graph ◽  
Linear Extensions ◽  
Acyclic Orientations ◽  
International Audience ◽  
General Graphs ◽  
Odd Cycles

International audience Given an underlying undirected simple graph, we consider the set of all acyclic orientations of its edges. Each of these orientations induces a partial order on the vertices of our graph, and therefore we can count the number of linear extensions of these posets. We want to know which choice of orientation maximizes the number of linear extensions of the corresponding poset, and this problem is solved essentially for comparability graphs and odd cycles, presenting several proofs. We then provide an inequality for general graphs and discuss further techniques.

scholarly journals Dyck tilings, linear extensions, descents, and inversions

2012 ◽  
Vol DMTCS Proceedings vol. AR,... (Proceedings) ◽  
Author(s):  
Jang Soo Kim ◽  
Karola Mészáros ◽  
Greta Panova ◽  
David B. Wilson
Keyword(s):  
Linear Extension ◽  
Lower Boundary ◽  
Linear Extensions ◽  
Young Diagrams ◽  
Dyck Paths ◽  
International Audience

International audience Dyck tilings were introduced by Kenyon and Wilson in their study of double-dimer pairings. They are certain kinds of tilings of skew Young diagrams with ribbon tiles shaped like Dyck paths. We give two bijections between "cover-inclusive'' Dyck tilings and linear extensions of tree posets. The first bijection maps the statistic (area + tiles)/2 to inversions of the linear extension, and the second bijection maps the "discrepancy'' between the upper and lower boundary of the tiling to descents of the linear extension. Les pavages de Dyck ont été introduits par Kenyon et Wilson dans leur étude du modèle des "double-dimères''. Ce sont des pavages des diagrammes de Young gauches avec des tuiles en forme de rubans qui ressemblent à des chemins de Dyck. Nous donnons deux bijections entre les pavages de Dyck ``couvre-inclusive'' et les extensions linéaires de posets dont le diagramme de Hasse est un arbre. La première bijection transforme la statistique (aire + tuiles) / 2 en inversions de l'extension linéaire, et la deuxième bijection transforme la "discordance'' entre la limite supérieure et inférieure du pavage en descentes de l'extension linéaire.

scholarly journals On q-integrals over order polytopes (extended abstract)

2020 ◽  
Vol DMTCS Proceedings, 28th... ◽  
Author(s):  
Jang Soo Kim
Keyword(s):  
Generating Function ◽  
Linear Extensions ◽  
Combinatorial Interpretation ◽  
Selberg Integral ◽  
Beta Integral ◽  
International Audience ◽  
Order Polytope

International audience A q-integral over an order polytope coming from a poset is interpreted as a generating function of linear extensions of the poset. As an application, theq-beta integral and aq-analog of Dirichlet’s integral are computed. A combinatorial interpretation of aq-Selberg integral is also obtained.

scholarly journals Poset vectors and generalized permutohedra

2013 ◽  
Vol DMTCS Proceedings vol. AS,... (Proceedings) ◽  
Author(s):  
Dorian Croitoru ◽  
Suho Oh ◽  
Alexander Postnikov
Keyword(s):  
Integer Lattice ◽  
Lattice Points ◽  
Linear Extensions ◽  
Integer Points ◽  
Nous Montrons ◽  
International Audience ◽  
Generalized Permutohedron

International audience We show that given a poset $P$ and and a subposet $Q$, the integer points obtained by restricting linear extensions of $P$ to $Q$ can be explained via integer lattice points of a generalized permutohedron. Nous montrons que, étant donné un poset $P$ et un subposet $Q$, les points entiers obtenus en restreignant les extensions linéaires de $P$ à $Q$peuvent être expliqués par les points entiers d’un permutohedron généralisé.

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