scholarly journals Rapidly mixing chain and perfect sampler for logarithmic separable concave distributions on simplex

2005 ◽  
Vol DMTCS Proceedings vol. AD,... (Proceedings) ◽  
Author(s):  
Shuji Kijima ◽  
Tomomi Matsui
Keyword(s):  
Probability Function ◽  
Discrete Distribution ◽  
Integral Point ◽  
Dimensional Simplex ◽  
Perfect Sampling ◽  
The Past ◽  
International Audience ◽  
Hit And Run ◽  
Multivariate Discrete Distribution ◽  
Dimensional Integral

International audience In this paper, we are concerned with random sampling of an n dimensional integral point on an $(n-1)$ dimensional simplex according to a multivariate discrete distribution. We employ sampling via Markov chain and propose two "hit-and-run'' chains, one is for approximate sampling and the other is for perfect sampling. We introduce an idea of <i>alternating inequalities </i> and show that a <i>logarithmic separable concave</i> function satisfies the alternating inequalities. If a probability function satisfies alternating inequalities, then our chain for approximate sampling mixes in $\textit{O}(n^2 \textit{ln}(Kɛ^{-1}))$, namely $(1/2)n(n-1) \textit{ln}(K ɛ^{-1})$, where $K$ is the side length of the simplex and $ɛ (0<ɛ<1)$ is an error rate. On the same condition, we design another chain and a perfect sampler based on monotone CFTP (Coupling from the Past). We discuss a condition that the expected number of total transitions of the chain in the perfect sampler is bounded by $\textit{O}(n^3 \textit{ln}(Kn))$.

Computer program for a fault-plane solution

1963 ◽  
Vol 53 (1) ◽  
pp. 1-13
Author(s):  
Keichi Kasahara
Keyword(s):  
Probability Function ◽  
Fault Plane ◽  
Successive Approximations ◽  
Standard Errors ◽  
Machine Time ◽  
The Past ◽  
First Approximation ◽  
Plane Solution ◽  
Earthquake Mechanism ◽  
Time Required

Abstract In its earthquake mechanism studies the Dominion Observatory has been producing solutions graphically, but a program based on a probability function defined by Knopoff has been written for the IBM 1620 which permits the best solution to be obtained by a series of successive approximations from a given first approximation. The program prints out the strike and dip of the two nodal planes, their standard errors, the azimuth and plunge of their line of intersection, and a list of the stations producing inconsistent data. Weights can be assigned to each station; in practice these weights would depend on the past reliablity of the station. The machine time required depends on the number of stations used, the accuracy of the first approximation and other factors; in general 20 to 30 minutes is required for a solution involving 30-40 stations.

scholarly journals The Bibliometric Analysis of Czech Geography in the Scopus Database

Geografie ◽  
2012 ◽  
Vol 117 (1) ◽  
pp. 52-71 ◽  
Author(s):  
Artur Bajerski ◽  
Tadeusz Siwek
Keyword(s):  
Bibliometric Analysis ◽  
Restricted Range ◽  
Geographical Research ◽  
Geographical Society ◽  
The Past ◽  
Exchange Of Information ◽  
International Audience ◽  
Regional Basis ◽  
Scopus Database

The analysis focuses on two journals: Geografie (published by the Czech Geographical Society in Czech and English) and Moravian Geographical Reports (only in English). The analysis demonstrates that the scope of both journals is only regional, due to their relatively restricted range of authors and citations: the first periodical functions mainly within Bohemia, with some overlap into other Czech regions, while the second is active primarily in Moravia, overlapping somewhat into Slovakia and Poland. Despite their status as premier Czech geographical periodicals, both journals serve mainly as conduits for the exchange of information among academics on a regional basis. Important papers presenting the results of Czech geographical research to a wide international audience are rarely featured in these journals; such research is usually published as monographs, as has been the case in the past. This paper lists the most frequently cited Czech geographers and interdisciplinary citations – especially in and from sociology and economics papers.

scholarly journals "Medusa's Smirk" (1975) by Mihaela Miroiu

Aspasia ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 147-150
Author(s):  
Maria Bucur
Keyword(s):  
Sexual Violence ◽  
Political Scientist ◽  
Traumatic Memories ◽  
The Past ◽  
International Audience ◽  
The One ◽  
Past Half ◽  
Half Decade

Over the past half decade, philosopher and political scientist Mihaela Miroiu published a series of short autobiographical stories that were eventually collected in a book, Cumintea mea de femeie [With my woman’s mind] (Bucharest: Cartea românească, 2017), which was reviewed in Aspasia (vol. 12) in 2018. While the whole volume deserves an international audience, I have selected the story “Medusa’s Smirk,” for translation because it sheds light on a topic little known, yet extremely important, in the lives of many women: sexual violence. Discussing sexual violence was a taboo topic under communism, and many women suppressed their traumatic memories of violence both seen and experienced. Yet accounts such as the one shared below have circulated orally and deserve further attention from scholars. For another relevant account, see http://www.publicseminar.org/2017/12/sex-in-the-time-of-communism/.

scholarly journals The structure of communication problems in cellular automata

2011 ◽  
Vol DMTCS Proceedings vol. AP,... (Proceedings) ◽  
Author(s):  
Raimundo Briceño ◽  
Pierre-Etienne Meunier
Keyword(s):  
Cellular Automata ◽  
Communication Complexity ◽  
Intrinsic Universality ◽  
The Past ◽  
Communication Problems ◽  
International Audience ◽  
Simulation Relations

International audience Studying cellular automata with methods from communication complexity appears to be a promising approach. In the past, interesting connections between communication complexity and intrinsic universality in cellular automata were shown. One of the last extensions of this theory was its generalization to various "communication problems'', or "questions'' one might ask about the dynamics of cellular automata. In this article, we aim at structuring these problems, and find what makes them interesting for the study of intrinsic universality and quasi-orders induced by simulation relations.

scholarly journals Counting quadrant walks via Tutte's invariant method (extended abstract)

2020 ◽  
Vol DMTCS Proceedings, 28th... ◽  
Author(s):  
Olivier Bernardi ◽  
Mireille Bousquet-Mélou ◽  
Kilian Raschel
Keyword(s):  
Differential Equation ◽  
Functional Equation ◽  
Linear Differential Equation ◽  
Generating Function ◽  
Algebraic Approach ◽  
Rational Functions ◽  
The Past ◽  
Lattice Walks ◽  
International Audience ◽  
Linear Differential

Extended abstract presented at the conference FPSAC 2016, Vancouver. International audience In the 1970s, Tutte developed a clever algebraic approach, based on certain " invariants " , to solve a functional equation that arises in the enumeration of properly colored triangulations. The enumeration of plane lattice walks confined to the first quadrant is governed by similar equations, and has led in the past decade to a rich collection of attractive results dealing with the nature (algebraic, D-finite or not) of the associated generating function, depending on the set of allowed steps. We first adapt Tutte's approach to prove (or reprove) the algebraicity of all quadrant models known or conjectured to be algebraic (with one small exception). This includes Gessel's famous model, and the first proof ever found for one model with weighted steps. To be applicable, the method requires the existence of two rational functions called invariant and decoupling function respectively. When they exist, algebraicity comes out (almost) automatically. Then, we move to an analytic viewpoint which has already proved very powerful, leading in particular to integral expressions of the generating function in the non-D-finite cases, as well as to proofs of non-D-finiteness. We develop in this context a weaker notion of invariant. Now all quadrant models have invariants, and for those that have in addition a decoupling function, we obtain integral-free expressions of the generating function, and a proof that this series is differentially algebraic (that is, satisfies a non-linear differential equation).

scholarly journals Latitudinal Gradient in Urban Pressure and Socio-Environmental Quality: The “Peninsula Effect” in Italy

Land ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 126 ◽  
Author(s):  
Bernardino Romano ◽  
Lorena Fiorini ◽  
Chiara Di Dato ◽  
Vanessa Tomei
Keyword(s):  
Urban Development ◽  
Environmental Quality ◽  
Continental Margin ◽  
Latitudinal Gradient ◽  
Southern Italy ◽  
Final Part ◽  
Behavioral Characteristics ◽  
The Past ◽  
International Audience

The purpose of this work is to synthesize, for an international audience, certain fundamental elements that characterize the Italian peninsular territory, through the use of a biogeographical model known as the “peninsula effect” (PE). Just as biodiversity in peninsulas tends to change, diverging from the continental margin, so do some socio-economic and behavioral characteristics, for which it is possible to detect a progressive and indisputable variation depending on the distance from the continental mass. Through the use of 14 indicators, a survey was conducted on the peninsular sensitivity (which in Italy is also latitudinal) of as many phenomena. It obtained confirmation results for some of them, well known as problematic for the country, but contradictory results for others, such as those related to urban development. In the final part, the work raises a series of questions, also showing how peninsular Italy, and in particular Central–Southern Italy, is not penalized so dramatically by its geography and morphology as many political and scientific opinions suggest. The result is a very ambiguous image of Italy, in which the country appears undoubtedly uniform in some aspects, while the PE is very evident in others; it is probably still necessary to investigate, without relying on simplistic and misleading equations, the profound reasons for some phenomena that could be at the basis of less ephemeral rebalancing policies than those practiced in the past.

scholarly journals Perfect sampling methods for random forests

2008 ◽  
Vol 40 (03) ◽  
pp. 897-917 ◽  
Author(s):  
Hongsheng Dai
Keyword(s):  
Random Forests ◽  
Probability Space ◽  
Sampling Methods ◽  
Weighted Graph ◽  
Rejection Sampling ◽  
Perfect Sampling ◽  
Target Distribution ◽  
The Past ◽  
Coupling From The Past ◽  
Vertex Set

A weighted graph G is a pair (V, ℰ) containing vertex set V and edge set ℰ, where each edge e ∈ ℰ is associated with a weight We . A subgraph of G is a forest if it has no cycles. All forests on the graph G form a probability space, where the probability of each forest is proportional to the product of the weights of its edges. This paper aims to simulate forests exactly from the target distribution. Methods based on coupling from the past (CFTP) and rejection sampling are presented. Comparisons of these methods are given theoretically and via simulation.

Understanding Basava: history, hagiography and a modern Kannada drama

1998 ◽  
Vol 61 (2) ◽  
pp. 228-261 ◽  
Author(s):  
Julia Leslie
Keyword(s):  
Twentieth Century ◽  
Religious Experience ◽  
Twelfth Century ◽  
Religious Studies ◽  
Social Implications ◽  
Religious Context ◽  
The Past ◽  
International Audience ◽  
Primary Focus ◽  
New Religion

This paper is a meditation from a religious studies perspective on the twelfth-century Vīraśaiva saint, Basava (c. 1105–68); that is, its primary focus is religious experience rather than literary evaluation or the historicity of the past. By exploring a variety of sources—ancient and modern, fact and fiction—and by making connections with urgent twentieth-century concerns, it seeks to bring into focus the religious aspirations and social implications of Basava's world. Part 1 is derived from history and hagiography. It provides an outline of Vīraśaiva belief and practice, and then proceeds to discuss the religious context of twelfth-century Karnataka, the debate regarding the origins of this ‘new’ religion, and a key inscription in the debate. It ends with a summary of the tradition's account of Basava's life. Part 2 focuses on a play written in Kannada (Taledaṇḍa, ‘Death by beheading’, 1990) and then rewritten in English for a pan-Indian and international audience (Talé-Daṇḍa: a play, 1993), in both cases by Girish Karnad. Karnad is not the first playwright to focus on Basava, and he will not be the last. In the preface to the Kannada version, he explains that ‘it becomes inevitable for every Kannadiga to return, like a tongue that returns again and again to a painful tooth, to the victories and agonies of that period.’ Karnad's dramatization of Basava's catastrophic final year is discussed in the context of the historical and hagiographical material considered in Part 1.

scholarly journals The frequency of pattern occurrence in random walks

2015 ◽  
Vol DMTCS Proceedings, 27th... (Proceedings) ◽  
Author(s):  
Sergi Elizalde ◽  
Megan Martinez
Keyword(s):  
Time Series ◽  
Random Walks ◽  
Permutation Patterns ◽  
Equal Frequency ◽  
Time Intervals ◽  
The Past ◽  
Data Points ◽  
International Audience ◽  
Ordinal Patterns ◽  
Analysis Of Time Series

International audience In the past decade, the use of ordinal patterns in the analysis of time series and dynamical systems has become an important tool. Ordinal patterns (otherwise known as a permutation patterns) are found in time series by taking $n$ data points at evenly-spaced time intervals and mapping them to a length-$n$ permutation determined by relative ordering. The frequency with which certain patterns occur is a useful statistic for such series. However, the behavior of the frequency of pattern occurrence is unstudied for most models. We look at the frequency of pattern occurrence in random walks in discrete time, and we define a natural equivalence relation on permutations under which equivalent patterns appear with equal frequency, regardless of probability distribution. We characterize these equivalence classes applying combinatorial methods. Au cours de la dernière décennie, l’utilisation des motifs ordinaux dans l’analyse des séries chronologiques et systèmes dynamiques est devenu un outil important. Des motifs ordinaux (autrement appelés motifs de permutations) se trouvent dans les séries chronologiques en prenant $n$ points de données au intervalles de temps uniformément espacées et les faisant correspondre à une permutation de longueur $n$ déterminée par leur ordre relatif. La fréquence avec laquelle certains motifs apparaissent est une statistique utile pour ces séries. Toutefois, le comportement de la fréquence d’apparition de ces motifs n’a pas été étudié pour la plupart des modèles. Nous regardons la fréquence d’occurrence des motifs dans les marches aléatoires en temps discret, et nous définissons une relation d’équivalence naturelle sur des permutations dans laquelle les motifs équivalents apparaissent avec la même fréquence, quelle que soit la distribution de probabilité. Nous caractérisons ces classes d’équivalence utilisant des méthodes combinatoires

scholarly journals Sign variation, the Grassmannian, and total positivity

2015 ◽  
Vol DMTCS Proceedings, 27th... (Proceedings) ◽  
Author(s):  
Steven N. Karp
Keyword(s):  
Total Positivity ◽  
Oriented Matroids ◽  
Plücker Coordinates ◽  
The Past ◽  
Sign Patterns ◽  
International Audience

International audience The <i>totally nonnegative Grassmannian</i> is the set of $k$-dimensional subspaces $V$ of &#8477;<sup>$n$</sup> whose nonzero Plücker coordinates (i.e. $k &times; k$ minors of a $k &times; n$ matrix whose rows span $V$) all have the same sign. Total positivity has been much studied in the past two decades from an algebraic, combinatorial, and topological perspective, but first arose in the theory of oscillations in analysis. It was in the latter context that Gantmakher and Krein (1950) and Schoenberg and Whitney (1951) independently showed that a subspace $V$ is totally nonnegative iff every vector in $V$, when viewed as a sequence of $n$ numbers and ignoring any zeros, changes sign fewer than $k$ times. We generalize this result, showing that the vectors in $V$ change sign fewer than $l$ times iff certain sequences of the Plücker coordinates of some <i>generic perturbation</i> of $V$ change sign fewer than $l &minus; k &plus; 1$ times. We give an algorithm which constructs such a generic perturbation. Also, we determine the <i>positroid cell</i> of each totally nonnegative $V$ from sign patterns of vectors in $V$. These results generalize to oriented matroids. La <i>grassmannienne totalement non négative</i> est l’ensemble des sous-espaces $V$ de &#8477;<sup>$n$</sup> de dimension $k$ dont coordonnées plückeriennes non nulles (mineurs de l’ordre $k$ d’une matrice $k &times; n$ dont les lignes engendrent $V$) ont toutes le même signe. La positivité totale a beaucoup été étudiée durant les deux dernières décennies d’une perspective algébrique, combinatoire, et topologique, mais a pris naissance dans la théorie analytique des oscillations. C’est dans ce contexte que Gantmakher et Krein (1950) et Schoenberg et Whitney (1951) ont indépendamment démontré qu’un sous-espace $V$ est totalement non négatif ssi chaque vecteur dans $V$, lorsque considéré comme une séquence de $n$ nombres et dont on ignore les zéros, change de signe moins de $k$ fois. Nous généralisons ce résultat, démontrant que les vecteurs dans $V$ changent de signe moins de $l$ fois ssi certaines séquences des coordonnées plückeriennes d’une <i>perturbation générique</i> de $V$ changent de signe moins de $l &minus; k &plus; 1$ fois. Un algorithme construisant une telle perturbation générique est obtenu. De plus, nous déterminons la <i>cellule positroïde</i> de chaque $V$ totalement non négatif à partir des données de signe des vecteurs dans $V$. Ces résultats sont valides pour les matroïdes orientés.

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