On Buffon Machines and Numbers

The well-know needle experiment of Buffon can be regarded as an analog (i.e., continuous) device that stochastically "computes" the number 2/pi ~ 0.63661, which is the experiment's probability of success. Generalizing the experiment and simplifying the computational framework, we consider probability distributions, which can be produced perfectly, from a discrete source of unbiased coin flips. We describe and analyse a few simple Buffon machines that generate geometric, Poisson, and logarithmic-series distributions. We provide human-accessible Buffon machines, which require a dozen coin flips or less, on average, and produce experiments whose probabilities of success are expressible in terms of numbers such as, exp(-1), log 2, sqrt(3), cos(1/4), aeta(5). Generally, we develop a collection of constructions based on simple probabilistic mechanisms that enable one to design Buffon experiments involving compositions of exponentials and logarithms, polylogarithms, direct and inverse trigonometric functions, algebraic and hypergeometric functions, as well as functions defined by integrals, such as the Gaussian error function.Comment: Largely revised version with references and figures added. 12 pages. In ACM-SIAM Symposium on Discrete Algorithms (SODA'2011

Îles-frontières, territoires impossibles?

Japan has a tradition of borders, not only at sea but also on land. Given the country's insularity and historical development, the former kind are the ones that will be of concern to international relations. Their demarcation, and the disputes that may arise with adjacent maritime countries (Russia, China, Korea), are a legacy of both history and geography. A remote island is not necessarily an ideal point for marking off a territory, as exemplified by the Takeshima/Tok-to islets which Japan and Korea have been disputing. The recent delimitation of maritime Exclusive Economic Zones is raising the stakes and stirring up tensions

A survey to evaluate how non designers perceive aesthetic properties of styling features

World-wide market competition and the need to create products that better satisfy the market expectations require a more comprehensive involvement of the customer in the product definition loop. Therefore, it is crucial to provide customers with very easy-to-use shape definition and modification tools, allowing them to verify and evaluate possible shape alternatives without requiring specific knowledge on geometric modeling. A set of aesthetic properties guiding the shape characterization and appraisal have been identified together with measures for their evaluation and shape modeling methods for their direct modification. Since these properties have been indicated by stylists, no guarantee exists that they are usable in a context directly involving customers in the product definition loop. To verify the extent to which the terms indicating the properties, their meaning and their measures are significant and understandable by non-expert designer people we carried out a survey. This paper describes the methodology adopted and the outcomes of this survey

The northern New Hebrides back-arc troughs : history and relation with the North Fiji basin

The New Hebrides back arc troughs (southwest Pacific) are located between the New Hebrides trench arc system and the active North Fiji marginal basin. They are restricted to the southern and northern segments of the arc and were generally related to effects of the Indo Australian subducting plate (rolling back and/or subduction of the d'Entrecasteaux ridge). A detailed bathymetric and magnetic survey over the northern back arc troughs is used to propose a new model for the origin of the New Hebrides back arc troughs. The northern troughs extend over a width of 60 km and are composed of N S trending grabens and horsts, discontinuous along strike and associated with volcanism. The troughs are disrupted southward at 13° 30'S, where the Hazel Holme fracture zone intercepts the New Hebrides island arc. The E W trending Hazel Holme fracture zone is an extensional feature bisecting the North Fiji basin. In its western end, the Hazel Hohne fracture zone is composed of a succession of horsts and grabens striking N90 ° N100 ° E. Geometrical and structural relationships between the back arc troughs and the Hazel Holme fracture zone suggest that both these extensional features result from the same process and are closely linked. The northern troughs western end of the Hazel Holme fracture zone region is dominated by N130° 135°E trending magnetic lineations typical of oceanic crust. These lineations are oblique to the horsts and grabens systems, and are characteristic of the old North Fiji basin oceanic crust. Consequently we conclude that the northern back arc troughs are partly developed on the North Fiji basin oceanic basement and that extensional tectonic processes postdate the oldest North Fiji basin oceanic crust. Morphological and structural evidence suggests that both the back arc troughs and the Hazel Holme fracture zone are recent, still active and result from NE SW extensional tectonics. Because other tectonic features throughout the North Fiji basin are related to the same stress field, it is inferred that such a NE SW extension could be a large scale deformation affecting the North Fiji basin. It is proposed that the back arc troughs are primarily related to this recent extension within the North Fiji basin, but their locations along the arc are also influenced by the subduction of the d'Entrecasteaux ridge which produces, south of 13°30'S, nearly E W trending compression and prevents the formation of troughs. Possibly, these recent extensional tectonic processes result from a major reorganization in the spreading process of the North Fiji basin, and could be as young as 0.6-0.7 Ma

Des mers de Chine à la mer du Japon : Un détroit sous influences nippo-coréennes

Historiquement, le détroit situé entre la Corée du Sud et le Japon, appelé officiellement «détroit de Corée» et parcouru par le puissant courant marin Ao-shio, est le lieu d’une civilisation originale, à l’extrémité orientale du continent asiatique. Les îles et les rives du détroit sont marquées par des échanges commerciaux anciens et une culture commune, mais aussi par de violents conflits et une piraterie endémique. L’île de Tsushima, au coeur du détroit, en est le témoin privilégié. Les litiges territoriaux pour l’exploitation des ressources maritimes, notamment halieutiques, sont dorénavant réglés dans le détroit, avec la délimitation des zones économiques exclusives. Actuellement, les tendances dominantes vont dans le sens des échanges transfrontaliers et de la construction d’une région économique autour du détroit.Historically, the strait between South Korea and Japan, officially designated the “Korea Strait” in which the powerful Ao-shio ocean current flows, is the place of a unique civilization at the eastern tip of the Asian mainland. The islands and shores of the strait have been marked by ancient commercial trade and shared cultures, but also by violent conflicts and endemic piracy. The island of Tsushima, in the centre of the strait, is the best example of this. Territorial disputes for the rights to maritime resources, fishing in particular, are in these days settled in the strait with exclusive economical zones delimitation. Today, trends are now shifting to cross border trade and development of an economic region within the strait

Le Japon, « la plus grande merveille de l’histoire », vu par Élisée Reclus et Léon Metchnikoff

Élisée Reclus (1830-1905) et Léon Metchnikoff (1838-1888), deux géographes anarchistes, proposent sur le Japon de Meiji une lecture qui est originale pour leur temps, et qui le reste encore vu son caractère innovant. Appelé par des dirigeants de Satsuma et ayant séjourné plus de deux ans à Tokyo (1874-1876) au début du nouveau régime, le second apporte au premier des éléments cruciaux qui lui permettent de considérer l’évolution du Japon comme étant autre chose qu’un simple processus d’occidentalisation ou d’imitation servile. Il s’agit d’un processus endogène qui puise dans la prise de conscience et la mémoire japonaises du danger impérialiste, ainsi que dans la profusion biogéographique de l’archipel. Reclus alerte également sur la montée en puissance belliciste et impérialiste du Japon, alors sous-estimée par la plupart de ses contemporains.エリゼ・ルクリュ（1830年～1905年）とレオン・メーチニコフ（1838年～1888年）は無政府主義の地理学者であり、明治時代の日本について独自の見解を残したが、その斬新さは今日でも失われていない。薩摩藩の指導者らに招かれ、明治新政府下の1874年から1876年にかけて東京に滞在したメーチニコフがもたらした重要な知見により、ルクリュは日本の変化が単なる西洋化もしくは卑屈な模倣ではないと考えた。それは帝国主義の危険性を意識し記憶した日本で内発的に起きたものであり、また、日本列島の生物地理学的な豊かさを源とするのである。同時にルクリュは、彼の同時代人たちからは過小評価されていた日本が、急激に好戦的かつ帝国主義的になりつつあることについて警鐘を鳴らしている。The anarchist geographers Élisée Reclus (1830–1905) and Léon Metchnikoff (1838–1888) offered an innovative vision of Meiji Japan that is as original now as it was in its day. Having spent over two years in Tokyo (1874–1876) at the invitation of Satsuma leaders, Metchnikoff provided Reclus with crucial elements that enabled him to consider the evolution of Japan as something other than a simple process of Westernisation or servile imitation. Instead, he saw it as an endogenous process rooted in Japan’s awareness and memory of the imperialist danger and in the country’s biogeographical abundance. Reclus also warned of the rising imperialist and militarist threat from Japan, which was underestimated at the time by the majority of his contemporaries

Fécondité des femmes immigrantes et descendantes d’immigrantes selon le statut conjugal au Québec

Au cours des dernières décennies, plusieurs changements sociaux survenus au Québec ont eu pour conséquence une perte d’intérêt pour le mariage et l’apparition de l’union libre en tant que statut socialement accepté. Avec les nouvelles mentalités liées à la réussite professionnelle et individuelle, la fécondité a baissé. Dans notre étude, nous comptons observer non seulement les écarts de fécondité par région de provenance, qui ont déjà fait l’objet de précédentes recherches, mais également ceux régis par le statut conjugal des femmes (mariées ou en union libre). L’objectif de notre recherche consiste à déterminer si la fécondité des immigrantes est plus élevée que celle des femmes natives et si les différences de fécondité en fonction des statuts conjugaux de mariée ou en union libre, sont identiques pour tous les groupes d’immigrantes et de femmes natives. Les résultats tirés du recensement canadien de 2006 nous ont permis de constater que la fécondité est plus élevée pour la plupart des femmes immigrantes. Cependant, en distinguant les mariées et celles en union libre on remarque que les femmes ayant une fécondité supérieure à celle des natives représentent une plus faible proportion que lorsque l’on considère l’ensemble des immigrantes. Bien qu’on observe des différences entre les statuts conjugaux, la tendance montre que les femmes qui ont une fécondité plus élevée dans le mariage par rapport aux natives sont également dans cette situation lorsqu’elles sont en union libre. Enfin, la majorité des femmes mariées ont un taux de fécondité plus élevé que celles en union libre.In recent decades, many social changes occurred in Quebec have resulted in a loss of interest in marriage and the emergence of common law as a socially accepted status. With new attitudes related to personal and professional success, fertility has declined. In our study, we want to observe not only the fertility differentials by region of origin, which have already been the subject of previous research, but also those covered by the marital status of women (married or common law). The objective of our research is to determine if the fertility of immigrant women is higher than that of native women and if differences in fertility according to marital status categories (married or in common law) are the same for all groups of immigrant and native women. Results from the 2006 Canadian census have revealed that fertility is higher for most immigrant women. But, distinguishing between married and common law we see that women with higher fertility than the native-born represent a smaller proportion when we consider all immigrants. Although there are differences between the marital status, the trend shows that women have higher fertility within marriage compared to native-born are also in this situation when in common law. Finally, the majority of married women hold a higher fertility rate than those in common law

La grande séparation à résorber : L’Orient et l’Occident vus par Elisée Reclus

Elisée Reclus (1830-1905), géographe anarchiste, a parcouru le monde entier mais ne s’est jamais rendu en Asie orientale. Grâce à d’excellentes informations récupérées grâce à son vaste et multiforme réseau de contacts, il a néanmoins beaucoup écrit sur celle-ci à la fin de sa vie. Il salue l’ancienneté, sinon l’origine commune, des civilisations en Orient et en Occident, tout en déplorant leur éloignement progressif dans le temps (l’histoire) et l’espace (la séparation montagneuse et désertique du Béloutchistan jusqu’à l’Ob, en passant par les barrières de l’Hindu Kouch et des Tian Shan). Constatant leur différentiel de puissance sur la scène mondiale, qui tourne à l’avantage de l’Europe et de l’Amérique, il en recherche les causes sur le temps long et l’espace profond, en maniant ainsi une approche de géohistoire et de géopolitique avant la lettre. Sa conception géographique de l’une ou l’autre des deux aires est pionnière. Sa façon de traiter la zone-limite le distingue du futur géopoliticien Mackinder. Ses remarques sur le Japon sont à maints égards prophétiques.Elisée Reclus (1830-1905), an anarchist geographer, travelled round the world but never went to the Far East. Owing to excellent information collected through a wide and varied network of connections, he nevertheless wrote extensively about it towards the end of his life. He celebrated the age, if not the common origin, of Western and Eastern civilizations, while regretting their gradual separation in time (through history), and space (through the steep and desolate boundary stretching from Baluchistan to the Ob’, including the barriers of Hindu Kush and of the Tian Shan). Observing that Europe and America were getting the upper hand on the world scene, he tried to determine the causes of this imbalance in history and in geography, thus implementing an early geohistorical and geopolitical method. He had a very innovative geographical conception of both regions. The way he tackled the borderline zone set him apart from the future geopolitics of Mackinder. His remarks on Japan appear in many ways prophetic

Révolution, évolution, progrès et régrès chez Élisée Reclus

Pour Élisée Reclus (1830-1905), géographe anarchiste, il n’y a pas de philosophie de l’histoire mais des variations de milieux (physiques, humains) faits de progrès et de régrès. Le progrès est une amélioration de la condition humaine : il « consiste à trouver l’ensemble des intérêts et des volontés commun à tous les peuples, il se confond avec la solidarité ». Nulle situation n’est figée puisque chaque milieu étant localement divers, chaque peuple peut effectuer des choix techniques et culturels différents malgré des conditions parfois proches. Reclus critique aussi bien les contempteurs que les laudateurs du progrès.For Élisée Reclus (1830-1905), the philosophy of history does not exist but there are many variations of « milieux » (physical and human) constitued by progress and « regress ». Progress is a way for improvement of human condition : it « means find the whole of interest and will common to all peoples, merged with solidarity ». No situation is fixed since each milieu is locally diverse, each people making technical and cultural choices in spite of similar conditions. Reclus is critical both towards people who admire or reject progress