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In this note we introduce several instructive examples of bijections found between several different combinatorially defined sequences of sets. Each sequence has cardinalities given by the Catalan numbers. Our results answer some questions…

Combinatorics · Mathematics 2013-03-01 Stefan Forcey , Mohammadmehdi Kafashan , Mehdi Maleki , Michael Strayer

Vincular and covincular patterns are generalizations of classical patterns allowing restrictions on the indices and values of the occurrences in a permutation. In this paper we study the integer sequences arising as the enumerations of…

Combinatorics · Mathematics 2017-06-12 Christian Bean , Anders Claesson , Henning Ulfarsson

We define a map between the set of permutations that avoid either the four patterns $3214,3241,4213,4231$ or $3124,3142,4123,4132$, and the set of Dyck prefixes. This map, when restricted to either of the two classes, turns out to be a…

Combinatorics · Mathematics 2013-01-10 Marilena Barnabei , Flavio Bonetti , Matteo Silimbani

We complete the enumeration of cyclic permutations avoiding two patterns of length three each by providing explicit formulas for all but one of the pairs for which no such formulas were known. The pair $(123,231)$ proves to be the most…

Combinatorics · Mathematics 2023-06-22 Miklos Bona , Michael Cory

Prior work on language model pre-training has explored different architectures and learning objectives, but differences in data, hyperparameters and evaluation make a principled comparison difficult. In this work, we focus on…

Computation and Language · Computer Science 2022-10-27 Mikel Artetxe , Jingfei Du , Naman Goyal , Luke Zettlemoyer , Ves Stoyanov

Language is contextual as meanings of words are dependent on their contexts. Contextuality is, concomitantly, a well-defined concept in quantum mechanics where it is considered a major resource for quantum computations. We investigate…

Computation and Language · Computer Science 2021-08-02 Daphne Wang , Mehrnoosh Sadrzadeh , Samson Abramsky , Victor H. Cervantes

The aim of this paper is two-fold. We first prove several new interpretations of a kind of $(q,t)$-Catalan numbers along with their corresponding $\gamma$-expansions using pattern avoiding permutations. Secondly, we give a complete…

Combinatorics · Mathematics 2018-10-16 Shishuo Fu , Dazhao Tang , Bin Han , Jiang Zeng

This paper presents a Bayesian model for unsupervised learning of verb selectional preferences. For each verb the model creates a Bayesian network whose architecture is determined by the lexical hierarchy of Wordnet and whose parameters are…

Computation and Language · Computer Science 2007-05-23 Massimiliano Ciaramita , Mark Johnson

Dokos et. al. studied the distribution of two statistics over permutations $\mathfrak{S}_n$ of $\{1,2,\dots, n\}$ that avoid one or more length three patterns. A permutation $\sigma\in\mathfrak{S}_n$ contains a pattern…

Combinatorics · Mathematics 2017-09-26 Samantha Dahlberg

We consider the avoidance of patterns in inversion sequences that relate sorting via sorting machines including data structures such as pop stacks and stacks. Such machines have been studied under a variety of additional constraints and…

Combinatorics · Mathematics 2025-02-12 Toufik Mansour , Howard Skogman , Rebecca Smith

While large language models (LLMs) demonstrate impressive capabilities across numerous applications, their robustness remains a critical concern. This paper is motivated by a specific vulnerability: the order sensitivity of LLMs. This…

Machine Learning · Computer Science 2025-05-22 Beni Egressy , Jan Stühmer

The Backpack is a Transformer alternative shown to improve interpretability in English language modeling by decomposing predictions into a weighted sum of token sense components. However, Backpacks' reliance on token-defined meaning raises…

Computation and Language · Computer Science 2023-10-20 Hao Sun , John Hewitt

A reformulation of the path length of binary search trees is given in terms of permutations, allowing to extend the definition to the instance of words, where the letters are obtained by independent geometric random variables (with…

Combinatorics · Mathematics 2007-05-23 Helmut Prodinger

We present an unsupervised word segmentation model, in which the learning objective is to maximize the generation probability of a sentence given its all possible segmentation. Such generation probability can be factorized into the…

Computation and Language · Computer Science 2021-03-03 Lihao Wang , Zongyi Li , Xiaoqing Zheng

In this paper we propose a notion of pattern avoidance in binary trees that generalizes the avoidance of contiguous tree patterns studied by Rowland and non-contiguous tree patterns studied by Dairyko, Pudwell, Tyner, and Wynn.…

Discrete Mathematics · Computer Science 2024-06-17 Petr Gregor , Torsten Mütze , Namrata

The usage of transformers has grown from learning about language semantics to forming meaningful visiolinguistic representations. These architectures are often over-parametrized, requiring large amounts of computation. In this work, we…

Computation and Language · Computer Science 2020-07-09 Prajjwal Bhargava

Layout-sensitive grammars have been adopted in many modern programming languages. However, tool support for this kind of grammars still remains limited and immature. In this paper, we present Lay-it-out, an interactive framework for…

Programming Languages · Computer Science 2022-03-31 Fengmin Zhu , Jiangyi Liu , Fei He

A frequent topic in the study of pattern avoidance is identifying when two sets of patterns $\Pi, \Pi'$ are Wilf equivalent, that is, when $|\text{Av}_n(\Pi)| = |\text{Av}_n(\Pi')|$ for all $n$. In recent work of Dokos et al. the notion of…

Combinatorics · Mathematics 2019-04-24 Caden Bielawa , Robert Davis , Daniel Greeson , Qinhan Zhou

An important task for the design of Question Answering systems is the selection of the sentence containing (or constituting) the answer from documents relevant to the asked question. Most previous work has only used the target sentence to…

Computation and Language · Computer Science 2020-06-03 Ivano Lauriola , Alessandro Moschitti

Context-free languages can be characterized in several ways. This article studies projective linearisations of languages of simple dependency trees, i.e., dependency trees in which a node can govern at most one node with a given syntactic…

Formal Languages and Automata Theory · Computer Science 2024-01-17 Carles Cardó