Flip invariance for domino tilings of three-dimensional regions with two floors

We investigate tilings of cubiculated regions with two simply connected floors by 2 x 1 x 1 bricks. More precisely, we study the flip connected component for such tilings, and provide an algebraic invariant that "almost" characterizes the flip connected components of such regions, in a sense that we discuss in the paper. We also introduce a new local move, the trit, which, together with the flip, connects the space of domino tilings when the two floors are identical.Comment: 33 pages, 34 figures, 2 tables. We updated the reference lis

Chile-Perú : las raíces de una difícil relación

En este artículo se abordan las relaciones entre Chile y Perú a partir de la persistencia de una serie de percepciones cruzadas, conformadas a partir de tres imágenes: la de país ganador frente a un país vencido, la de invasor e invadido y, por último, la de un país exitoso y estable frente a la imagen de un país políticamente inestable y con altos niveles de pobreza.  El análisis considera la existencia de factores esenciales, que cruzan transversalmente la vinculación entre estos dos países, como son la desconfianza histórica y la presencia de diferencias culturales vitales entre ambas naciones.  En su conjunto, estos factores permiten entender las limitantes que existen para alcanzar una vinculación más profunda; para dar un salto cualitativo que supere la herencia del pasado

The industry of microbreweries in the canton of Geneva: what are the current challenges faced by microbreweries in the market of Geneva and who are their customers ?

Switzerland is the country with the highest number of breweries per capita in the world (Genillard, 2018). In 2019, the number of microbreweries is around 1000. However, it has not always been the case that Switzerland was the leading country in terms of number of microbreweries. Indeed, in 1990, there were only 32 microbreweries in Switzerland. This phenomenon is something recent and even if the number has not stopped rising since 1990, there are many microbreweries that have failed to launch their enterprise which disappeared or went bankrupt. This bachelor project aims at identifying the diverse challenges faced by the microbrewers in the canton of Geneva. Moreover, the project also tries to build a consumer profile as well as identifying the important features of craft beers for the consumers. There are three different challenges identified that microbrewers in the canton of Geneva encounter. The first one being the difficulty to find a production warehouse and/or selling point. Indeed, it is quite expensive and constraining for diverse reasons. The second challenge identified is the initial investment and the machinery to be able to brew. The third challenge is the access to financing. Daily management and other important matters to think about are also addressed by this report. This report also addresses the future of the industry of microbrewery as well as the existing consortium. The future of the industry is currently difficult to forecast. Regarding the consumer profile, the key finding was that a typical consumer profile can be drawn. There are some factors that are relevant such as gender, income, occupation and education and some other that are inconclusive such as age. Plus, many different reasons where found to understand why a person do not drink a craft beer. The percentage of people that drinks craft beer was also identified. The findings show that consumers drink either often craft beers or drink it on a casual basis. The typical place where consumers drink craft beer was examined. The easiness of finding craft beer was analysed on the consumer point of view. Then, an investigation of the average amount spend by consumer was done and it seems that in average people spend up to 50 CHF per month. The features of craft beers that are important for consumers were also looked at. Plus, this report analyses if consumers living in Geneva consume mostly craft beers from Geneva or other places. Furthermore, craft beer was studied to see if this is something recently consumed in Geneva. Lastly, the favourite beers/microbreweries were identified for consumers in the market of Geneva

The Discriminatory Effect of Domestic Regulations on International Trade in Services: Evidence from Firm-Level Data

URL des Documents de travail : http://centredeconomiesorbonne.univ-paris1.fr/bandeau-haut/documents-de-travail/Documents de travail du Centre d'Economie de la Sorbonne 2013.19 - ISSN : 1955-611XIn order to promote international trade in services, the WTO-GATS aims at progressively eliminating discriminatory regulations, which apply to foreign suppliers, byguaranteeing equal national treatment. This paper looks instead at the trade effect of domestic regulations, which apply to all firms indifferently and do not intend to exclude foreign suppliers. We propose a theory-based empirical test to determine whether or not these domestic regulations affect foreign suppliers more than local ones. We take this test to the data by using French firm-level exports of professional services to OECD countries. Our econometric results show that domestic regulations in the importing markets matter significantly for trade in services. They reduce both the decision to export and the individual exports. These results tend to prove that domestic regulations are de facto discriminatory even if they are not de jure.Afin de promouvoir le commerce international de services, l'AGCS (OMC) a pour but l'élimination des régulations discriminantes qui s'appliquent aux entreprises étrangères, en garantissant un accès au marché identique à toutes les entreprises. Dans cet article, nous nous intéressons aux régulations qui sont non discriminantes par nature, et s'appliquent de manière identique aux entreprises domestiques et étrangères. Nous proposons un test empirique basé sur un modèle simple de commerce international avec firmes hétérogènes, afin de déterminer si ces régulations affectent plus les entreprises étrangères que les entreprises domestiques. Nous utilisons des données individuelles sur les exportations de services professionnels par les entreprises françaises vers les pays de l'OCDE. Nos résultats montrent que les régulations dans les secteurs des services des pays importateurs constituent une barrière importante au commerce international de services. Ces régulations réduisent à la fois la probabilité d'exporter, et les exportations individuelles. Ces résultats montrent que les régulations domestiques sont discriminantes de facto, même si elles ne le sont pas de jure

Domino tilings of three-dimensional regions: flips, trits and twists

In this paper, we consider domino tilings of regions of the form $\mathcal{D} \times [0,n]$, where $\mathcal{D}$ is a simply connected planar region and $n \in \mathbb{N}$. It turns out that, in nontrivial examples, the set of such tilings is not connected by flips, i.e., the local move performed by removing two adjacent dominoes and placing them back in another position. We define an algebraic invariant, the twist, which partially characterizes the connected components by flips of the space of tilings of such a region. Another local move, the trit, consists of removing three adjacent dominoes, no two of them parallel, and placing them back in the only other possible position: performing a trit alters the twist by $\pm 1$. We give a simple combinatorial formula for the twist, as well as an interpretation via knot theory. We prove several results about the twist, such as the fact that it is an integer and that it has additive properties for suitable decompositions of a region.Comment: 38 pages, 17 figures. Most of this material is also covered in the first author's Ph.D. thesis (arXiv:1503.04617

Shadowing and Lighting Acceleration

Cílem této práce je prezentovat metody pro akceleraci výpočtů stínů a osvětlení.  Práce se zabývá akcelerací na vzorek přesných stínů pomocí stínových těles na různých platformách. Obsahem práce je také zvýšení přesnosti stínových map a zvýšení přesnosti osvětlování scény s mnoha světly.The goal of the thesis is to present methods for acceleration of shadows and lighting. The main focus of the thesis is an acceleration of per-sample precise shadows using shadow volumes on different platforms. Other parts of this thesis also describe methods for increasing the precision of shadow map based methods and lighting.