Transport networks’ accessibility and jobs’ accessibility: the significance of this correlation on the configuration of labor market and their consequences on social configuration in the city Bogotá

Several researches have been done about transport in Bogotá (Colombia) but no one has treated the impact of the transport network on the configuration of employment in the city. This research has two different aims which are directly interrelated. The definition of the effective size of labor market in the city is necessary to sheds light on the relation of transport accessibility and type of jobs or social classes within different zones in Bogotá. We support the first part of our study on the existing literature about the effective size of labor market. Under the specification of a conceptual model, we want to demonstrate the significant correlation (even causality) between accessibility and type of jobs in Bogotá. In order to capture the possible endogeneity among transport' accessibility and type of jobs we will use a Structural Equation Modeling (SEM). Results will give us enough tools to know if transport network' accessibility, jobs' accessibility and type of jobs (or social classes) are large interrelated or not in the city of Bogotá. It will also let us to know if improvement of public network infrastructures traduced in a tacit enhancement on accessibility has a positive effect on incomes of inhabitants. We will understand the degree of correlation between accessibility to public transports and accessibility to jobs with respect to type of jobs and/or social class of labor force. Actually, first results show us that, there is a direct relationship between socio-economic class and time accessibility to jobs; the more accessibility of public transport system is in a zone of the city, the best is the social class and the better are the type of jobs of inhabitants so the highest will be the income. Nevertheless, it is observed (but not proved yet) that in some zones of the city where accessibility index is high, social class and types of jobs of inhabitants connected and living in these zones are not the best ones. Even so, we hope that with our methodology and data we could collect, we will be able to elucidate our research question.

Towards a Unified Framework for Declarative Structured Communications

We present a unified framework for the declarative analysis of structured communications. By relying on a (timed) concurrent constraint programming language, we show that in addition to the usual operational techniques from process calculi, the analysis of structured communications can elegantly exploit logic-based reasoning techniques. We introduce a declarative interpretation of the language for structured communications proposed by Honda, Vasconcelos, and Kubo. Distinguishing features of our approach are: the possibility of including partial information (constraints) in the session model; the use of explicit time for reasoning about session duration and expiration; a tight correspondence with logic, which formally relates session execution and linear-time temporal logic formulas

Are public transport improvements endogenous with respect to employment and income location in a city?

URL des Documents de travail : http://centredeconomiesorbonne.univ-paris1.fr/Documents de travail du Centre d'Economie de la Sorbonne 2014.12 - ISSN : 1955-611XPrevious research has proved the existence of a causal relationship between the concentration of jobs in a city and the income of inhabitants. Other researchers have studied the close and nearly causal relationship between those variables and the infrastructure such as highways in different zones of a city. Nevertheless, no one study has taken into account the degree to which each area of a city benefits from the latest improvements to public transport. The aim of this research is to analyse the relationship between the size of the labour market, the income and the employment concentration with respect to improvements to public transport (Transmilenio) in Bogota. The degree of enhancement of public transport in a zone is suspected to be endogenous. Through the use of OLS estimations and then 2SLS, the validation of endogeneity provides sufficient tools to infer causality of improvement of public transport. The size of companies, defined by the number of jobs they offer, plays the role of instrumental variable. In essence, the number of jobs, the size of the labour market and income are largely defined by the level of improvement to urban public transport in each zone of the city but the causality relationship changes depending on the size of companies established in each zone. In the case of Bogota, public transport improvements seams to have a causality relationship with the income of inhabitants in each zone and the number of jobs, and this changes with respect to the size of enterprises. In contrast, the size of the labour market, defined as the number of jobs reachable in a specific time, is not determined by the degree of the presence of public transport enhancement.L'existence d'une relation causale entre la concentration des emplois urbains et le niveau des revenus de ses habitants a été démontrée dans de précédentes études. Cependant, aucune étude ne s'est penchée sur l'impact de l'amélioration des transports publics sur les différentes zones intra-urbaines. L'objectif de cet article est d'analyser la relation entre la taille effective du marché du travail, le niveau de revenu de ses habitants et la concentration des emplois dans chaque zone de Bogota par rapport au degré dont chaque zone de la ville bénéfice de la présence de Transmilenio. Une analyse approfondie de l'éventuelle endogénéité de Transmilenio sur les trois variables à expliquer à l'aide des estimations OLS et 2SLS permet d'inférer une possible relation causale entre Transmilenio et les variables à expliquer. Les résultats montrent que la présence d'un nouveau système de transport public a une relation causale sur le niveau de revenu des habitants et sur la concentration des emplois mais que cet effet est fonction de la taille des entreprises dans chaque zone de la ville. Enfin, la présence de Transmilenio semble ne pas avoir d'effet direct sur la taille effective du marché du travail

A Constraint-based Language for Multiparty Interactions.

Abstract Multiparty interactions are common place in today's distributed systems. An agent usually communicates, in a single session, with other agents to accomplish a given task. Take for instance an online transaction including the vendor, the client, the credit card system and the bank. When specifying this kind of system, we probably observe a single transaction including several (binary) communications leading to changes in the state of all the involved agents. Multiway synchronization process calculi, that move from a binary to a multiparty synchronization discipline, have been proposed to formally study the behavior of those systems. However, adopting models such as Bodei, Brodo, and Bruni's Core Network Algebra (CNA), where the number of participants in an interaction is not fixed a priori, leads to an exponential blow-up in the number of states/behaviors that can be observed from the system. In this paper we explore mechanisms to tackle this problem. We extend CNA with constraints that declaratively allow the modeler to restrict the interaction that should actually happen. Our extended process algebra, called CCNA, finds application in balancing the interactions in a concurrent system, leading to a simple, deadlock-free and fair solution for the Dinning Philosopher problem. Our definition of constraints is general enough and it offers the possibility of accumulating costs in a multiparty negotiation. Hence, only computations respecting the thresholds imposed by the modeler are observed. We use this machinery to neatly model a Service Level Agreement protocol. We develop the theory of CCNA including its operational semantics and a behavioral equivalence that we prove to be a congruence. We also propose a prototypical implementation that allows us to verify, automatically, some of the systems explored in the paper

Universal Concurrent Constraint Programing: Symbolic Semantics and Applications to Security

International audienceWe introduce the Universal Timed Concurrent Constraint Programming (utcc) process calculus; a generalisation of Timed Concurrent Constraint Programming. The utcc calculus allows for the specification of mobile behaviours in the sense of Milner's pi-calculus: Generation and communication of private channels or links. We first endow utcc with an operational semantics and then with a symbolic semantics to deal with problematic operational aspects involving infinitely many substitutions and divergent internal computations. The novelty of the symbolic semantics is to use temporal constraints to represent finitely infinitely-many substitutions. We also show that utcc has a strong connection with Pnueli's Temporal Logic. This connection can be used to prove reachability properties of utcc processes. As a compelling example, we use utcc to exhibit the secrecy flaw of the Needham-Schroeder security protocol