scholarly journals Latin square Thue-Morse sequences are overlap-free

2007 ◽  
Vol Vol. 9 no. 1 (Automata, Logic and Semantics) ◽  
Author(s):  
C. Robinson Tompkins
Keyword(s):  
Fixed Points ◽  
Latin Square ◽  
International Audience

Automata, Logic and Semantics International audience We define a morphism based upon a Latin square that generalizes the Thue-Morse morphism. We prove that fixed points of this morphism are overlap-free sequences, generalizing results of Allouche - Shallit and Frid.

scholarly journals Hadamard matrices of order 36 and double-even self-dual [72,36,12] codes

2005 ◽  
Vol DMTCS Proceedings vol. AE,... (Proceedings) ◽  
Author(s):  
Iliya Bouyukliev ◽  
Veerle Fack ◽  
Joost Winne
Keyword(s):  
Fixed Points ◽  
Hadamard Matrices ◽  
Dual Codes ◽  
International Audience

International audience Before this work, at least 762 inequivalent Hadamard matrices of order 36 were known. We found 7238 Hadamard matrices of order 36 and 522 inequivalent [72,36,12] double-even self-dual codes which are obtained from all 2-(35,17,8) designs with an automorphism of order 3 and 2 fixed points and blocks.

scholarly journals A new generation tree for permutations, preserving the number of fixed points

2014 ◽  
Vol DMTCS Proceedings vol. AT,... (Proceedings) ◽  
Author(s):  
Philippe Duchon ◽  
Romaric Duvignau
Keyword(s):  
Fixed Points ◽  
Random Number ◽  
Random Number Generator ◽  
Specific Property ◽  
Number Generator ◽  
Random Generation ◽  
Combinatorial Algorithm ◽  
International Audience ◽  
Uniform Generation ◽  
New Generation

International audience We describe a new uniform generation tree for permutations with the specific property that, for most permutations, all of their descendants in the generation tree have the same number of fixed points. Our tree is optimal for the number of permutations having this property. We then use this tree to describe a new random generation algorithm for derangements, using an expected n+O(1) calls to a random number generator. Another application is a combinatorial algorithm for exact sampling from the Poisson distribution with parameter 1.

scholarly journals The $q=-1$ phenomenon for bounded (plane) partitions via homology concentration

2009 ◽  
Vol DMTCS Proceedings vol. AK,... (Proceedings) ◽  
Author(s):  
P. Hersh ◽  
J. Shareshian ◽  
D. Stanton
Keyword(s):  
Fixed Points ◽  
General Framework ◽  
Plane Partitions ◽  
International Audience

International audience Algebraic complexes whose "faces'' are indexed by partitions and plane partitions are introduced, and their homology is proven to be concentrated in even dimensions with homology basis indexed by fixed points of an involution, thereby explaining topologically two quite important instances of Stembridge's $q=-1$ phenomenon. A more general framework of invariant and coinvariant complexes with coefficients taken $\mod 2$ is developed, and as a part of this story an analogous topological result for necklaces is conjectured. Complexes algébriques dont les "faces'' sont indexées par des partitions et des partitions planes sont introduits. Il est démontré que leur homologie est concentrée en dimensions paires, avec base de homologie indexée par des points fixes d'une involution. Ce résultat explique d'une manière topologique deux instances du phénomène $q=-1$ dû a Stembridge. De plus, un cadre plus général des complexes invariants et coinvariants dont les coefficients sont pris modulo $2$ est développé. Comme part de cette histoire, nous conjecturons un résultat analogue pour des colliers.

scholarly journals Cyclic Sieving, Promotion, and Representation Theory

2008 ◽  
Vol DMTCS Proceedings vol. AJ,... (Proceedings) ◽  
Author(s):  
Brendon Rhoades
Keyword(s):  
Representation Theory ◽  
Fixed Points ◽  
Canonical Basis ◽  
Dihedral Groups ◽  
Jeu De Taquin ◽  
Noncrossing Partitions ◽  
Dual Canonical Basis ◽  
International Audience ◽  
Cyclic Sieving

International audience We prove a collection of conjectures due to Abuzzahab-Korson-Li-Meyer, Reiner, and White regarding the cyclic sieving phenomenon as it applies to jeu-de-taquin promotion on rectangular tableaux. To do this, we use Kazhdan-Lusztig theory and a characterization of the dual canonical basis of $\mathbb{C}[x_{11}, \ldots , x_{nn}]$ due to Skandera. Afterwards, we extend our results to analyzing the fixed points of a dihedral action on rectangular tableaux generated by promotion and evacuation, suggesting a possible sieving phenomenon for dihedral groups. Finally, we give applications of this theory to cyclic sieving phenomena involving reduced words for the long elements of hyperoctohedral groups, handshake patterns, and noncrossing partitions.

scholarly journals The Bruhat order on conjugation-invariant sets of involutions in the symmetric group

2015 ◽  
Vol DMTCS Proceedings, 27th... (Proceedings) ◽  
Author(s):  
Mikael Hansson
Keyword(s):  
Fixed Point ◽  
Symmetric Group ◽  
Fixed Points ◽  
Bruhat Order ◽  
Rank Function ◽  
Invariant Sets ◽  
Graded Poset ◽  
International Audience ◽  
Complete Characterisation

12 pages, 3 figures International audience Let $I_n$ be the set of involutions in the symmetric group $S_n$, and for $A \subseteq \{0,1,\ldots,n\}$, let \[ F_n^A=\{\sigma \in I_n \mid \text{$\sigma$ has $a$ fixed points for some $a \in A$}\}. \] We give a complete characterisation of the sets $A$ for which $F_n^A$, with the order induced by the Bruhat order on $S_n$, is a graded poset. In particular, we prove that $F_n^{\{1\}}$ (i.e., the set of involutions with exactly one fixed point) is graded, which settles a conjecture of Hultman in the affirmative. When $F_n^A$ is graded, we give its rank function. We also give a short new proof of the EL-shellability of $F_n^{\{0\}}$ (i.e., the set of fixed point-free involutions), which was recently proved by Can, Cherniavsky, and Twelbeck. Soit $I_n$ l’ensemble d’involutions dans le groupe symétrique $S_n$, et pour $A \subseteq \{0,1,\ldots,n\}$, soit\[ F_n^A=\{\sigma \in I_n \mid \text{$\sigma$ a $a$ points fixes pour quelque $a \in A$}\}. \] Nous caractérisons tous les ensembles $A$ dont les $F_n^A$ , avec l’ordre induit par l’ordre de Bruhat sur $S_n$, est un posetgradué. En particulier, nous démontrons que $F_n^{\{1\}}$ (c’est-à-dire, l’ensemble d’involutions avec précis en point fixe)est gradué, ce qui résout une conjecture d’Hultman à l’affirmative. Lorsque $F_n^A$ est gradué, nous donnons sa fonctionde rang. En plus, nous donnons une nouvelle démonstration courte l’EL-shellability de $F_n^{\{0\}}$ (c’est-à-dire, l’ensembled’involutions sans points fixes), établie récemment par Can, Cherniavsky et Twelbeck.

scholarly journals Cyclic Sieving and Plethysm Coefficients

2015 ◽  
Vol DMTCS Proceedings, 27th... (Proceedings) ◽  
Author(s):  
David B Rush
Keyword(s):  
Fixed Points ◽  
Schur Function ◽  
Young Tableaux ◽  
Jeu De Taquin ◽  
Cyclic Action ◽  
Domino Tableaux ◽  
Ribbon Tableaux ◽  
International Audience ◽  
Cyclic Sieving ◽  
Element Set

International audience A combinatorial expression for the coefficient of the Schur function $s_{\lambda}$ in the expansion of the plethysm $p_{n/d}^d \circ s_{\mu}$ is given for all $d$ dividing $n$ for the cases in which $n=2$ or $\lambda$ is rectangular. In these cases, the coefficient $\langle p_{n/d}^d \circ s_{\mu}, s_{\lambda} \rangle$ is shown to count, up to sign, the number of fixed points of an $\langle s_{\mu}^n, s_{\lambda} \rangle$-element set under the $d^e$ power of an order $n$ cyclic action. If $n=2$, the action is the Schützenberger involution on semistandard Young tableaux (also known as evacuation), and, if $\lambda$ is rectangular, the action is a certain power of Schützenberger and Shimozono's <i>jeu-de-taquin</i> promotion.This work extends results of Stembridge and Rhoades linking fixed points of the Schützenberger actions to ribbon tableaux enumeration. The conclusion for the case $n=2$ is equivalent to the domino tableaux rule of Carré and Leclerc for discriminating between the symmetric and antisymmetric parts of the square of a Schur function. Une expression combinatoire pour le coefficient de la fonction de Schur $s_{\lambda}$ dans l’expansion du pléthysme $p_{n/d}^d \circ s_{\mu}$ est donné pour tous $d$ que disent $n$, dans les cas où $n=2$, ou $\lambda$ est rectangulaire. Dans ces cas, le coefficient $\langle p_{n/d}^d \circ s_{\mu}, s_{\lambda} \rangle$ se montre à compter, où l’on ignore le signe, le nombre des point fixés d’un ensemble de $\langle s_{\mu}^n, s_{\lambda} \rangle$ éléments sous la puissance $d^e$ d’une action cyclique de l’ordre $n$. Si $n=2$, l’action est l’involution de Schützenberger sur les tableaux semi-standard de Young (aussi connu sous le nom des évacuations), et si $\lambda$ est rectangulaire, l’action est une certaine puissance de l’avancement jeu-de-taquin de Schützenberger et Shimozono.Ce travail étend les résultats de Stembridge et Rhoades, liant les point fixés des actions de Schützenberger aux tableaux de ruban. Pour le cas $n=2$ , la conclusion est équivalent à la règle des tableaux de dominos de Carré et Leclerc, qui distingue entre les parties symétriques et asymétriques du carré d’une fonction de Schur.

scholarly journals A bijection between irreducible k-shapes and surjective pistols of height $k-1$

2014 ◽  
Vol DMTCS Proceedings vol. AT,... (Proceedings) ◽  
Author(s):  
Ange Bigeni
Keyword(s):  
Fixed Points ◽  
International Audience

International audience This paper constructs a bijection between irreducible $k$-shapes and surjective pistols of height $k-1$, which carries the "free $k$-sites" to the fixed points of surjective pistols. The bijection confirms a conjecture of Hivert and Mallet (FPSAC 2011) that the number of irreducible $k$-shape is counted by the Genocchi number $G_{2k}$. On construit une bijection entre les $k$-formes irréductibles et les pistolets surjectifs de hauteur $k-1$ qui envoie les ”$k$-sites libres” sur les points fixes des pistolets. Cette bijection démontre une conjecture de Hivert et Mallet (FPSAC 2011), selon laquelle les $k$-formes irréductibles sont comptées par les nombres de Genocchi $G_{2k}$.

scholarly journals The largest singletons in weighted set partitions and its applications

2011 ◽  
Vol Vol. 13 no. 3 (Combinatorics) ◽  
Author(s):  
Yidong Sun ◽  
Yanjie Xu
Keyword(s):  
Fixed Points ◽  
Combinatorial Identities ◽  
Total Weight ◽  
Explicit Formulas ◽  
Set Partitions ◽  
International Audience ◽  
Combinatorial Methods

Combinatorics International audience Recently, Deutsch and Elizalde studied the largest fixed points of permutations. Motivated by their work, we consider the analogous problems in weighted set partitions. Let A (n,k) (t) denote the total weight of partitions on [n + 1] = \1,2,..., n + 1\ with the largest singleton \k + 1\. In this paper, explicit formulas for A (n,k) (t) and many combinatorial identities involving A (n,k) (t) are obtained by umbral operators and combinatorial methods. In particular, the permutation case leads to an identity related to tree enumerations, namely, [GRAPHICS] where D-k is the number of permutations of [k] with no fixed points.

scholarly journals On uniform recurrence of a direct product

2010 ◽  
Vol Vol. 12 no. 4 ◽  
Author(s):  
Pavel Vadimovich Salimov
Keyword(s):  
Fixed Points ◽  
Direct Product ◽  
Special Issue ◽  
Infinite Word ◽  
International Audience ◽  
Bounded Gaps ◽  
Recurrent Word

special issue dedicated to the second edition of the conference AutoMathA: from Mathematics to Applications International audience The direct product of two words is a naturally defined word on the alphabet of pairs of symbols. An infinite word is uniformly recurrent if each its subword occurs in it with bounded gaps. An infinite word is strongly recurrent if the direct product of it with each uniformly recurrent word is also uniformly recurrent. We prove that fixed points of the expanding binary symmetric morphisms are strongly recurrent. In particular, such is the Thue-Morse word.

scholarly journals On the set of Fixed Points of the Parallel Symmetric Sand Pile Model

2011 ◽  
Vol DMTCS Proceedings vol. AP,... (Proceedings) ◽  
Author(s):  
Kévin Perrot ◽  
Thi Ha Duong Phan ◽  
Trung Van Pham
Keyword(s):  
Fixed Points ◽  
Lexicographic Order ◽  
Sand Pile ◽  
Self Organized ◽  
Successor Relation ◽  
Self Organized Criticality ◽  
International Audience ◽  
Transition Rules ◽  
The Difference ◽  
Pile Model

International audience Sand Pile Models are discrete dynamical systems emphasizing the phenomenon of $\textit{Self-Organized Criticality}$. From a configuration composed of a finite number of stacked grains, we apply on every possible positions (in parallel) two grain moving transition rules. The transition rules permit one grain to fall to its right or left (symmetric) neighboring column if the difference of height between those columns is larger than 2. The model is nondeterministic and grains always fall downward. We propose a study of the set of fixed points reachable in the Parallel Symmetric Sand Pile Model (PSSPM). Using a comparison with the Symmetric Sand Pile Model (SSPM) on which rules are applied once at each iteration, we get a continuity property. This property states that within PSSPM we can't reach every fixed points of SSPM, but a continuous subset according to the lexicographic order. Moreover we define a successor relation to browse exhaustively the sets of fixed points of those models.

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