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This chapter presents a set of alternatives of modelling depending on the quantitative nature of the elements. Some systems allow different setup for its elements. We analyze the alternatives to reach the optimal setup respect to the quantitative nature of the elements. Also a couple of cases with special nuances on the measurable character of the elements are presented.

In this chapter we are going to define the general structure that we are going to give to a mathematical programming model, without going into detail about its components. The components of the structure will be described from the following chapter. Here we will only define the relationships between them. We will also expose the analogy of the components of our structure with the classical components defined for mathematical programming models. Finally, two simple examples will be presented to illustrate the structure model.

In this chapter we define the first component of a model, the elements of the system where the optimization problem is stated. The definition of an element implies the definition of its data and its quantitative nature in the system. We will structure all the information of a problem through the elements data, presenting different alternatives to set up the information of some system. The quantitative nature of the elements will be used as a tool to help define correctly decision activities.

This chapter studies the main part of a mathematical programming model, the constraints. We integrate the concept of constraints on the concept of specification, giving a classification of specifications in two levels, first depending of the type of statement and second depending on the semantic. A complete scheme for the modelling of compound propositions is proposed. Important aspects as the identification of implicit specifications in a system and its relation with the elements also are defined in the chapter.

Los estudios de transporte urbano se han caracterizado por centrarse en el análisis de los problemas de movilidad entre dife-rentes zonas, buscando principalmente la minimización del tiempo de viaje. En los últimos años han cobrado gran importancia los efectos negativos (externalidades) que la movilidad urbana gene-ra, entre ellos los aspectos ambientales. La movilidad con motivo de viaje a campus o centros universitarios supone un gran núme-ro de los desplazamientos realizados dentro de la ciudad. En este estudio se describen los patrones de movilidad de los estudiantes, trabajadores y residentes en un campus universitario integrado en un entorno urbano. Se realiza una evaluación del consumo ener-gético y las emisiones de contaminantes emitidas a la atmosfera provocados por estos desplazamientos, y así tener un mayor nivel de concienciación sobre el daño producido al medio ambiente. De las conclusiones obtenidas en este trabajo se debe destacar que aunque existan modos de transportes más sostenibles, menos contaminaste y más económicos, las personas se resisten a utili-zarlos mientras existan infraestructuras que permitan el uso de otros modos más contaminantes y menos sostenibles, ya sea por el tiempo, comodidad o porque les cuesta cambiar de hábitos. Para poder incentivar estos usos más sostenibles, primero hay que concienciar a las personas de la contaminación que están pro-duciendo e igualmente facilitar, incentivar y potenciar los modos más sostenibles; y por otro lado, penalizar los más contaminantes y menos sostenibles • Urban transport studies have been characterized by focusing on the analysis of mobility problems between different areas, mainly looking to minimize travel time. In recent years, negative effects (externalities) of urban mobility have become very important because of environmental aspects. Mobility to campus or universities represents a large number of journeys within city. In this study, mobility patterns of students, workers and residents in an integrated urban campus environment are described. An assessment of energy consumption and emissions of pollutants into the atmosphere, caused by these displacements, to have a higher level of awareness of damage caused to environment was proposed. The paper conclusions are that although there are ways more sustainable, less polluted and more economical transport, people are reluctant to use them. Thereason is that while there are infrastructures that allow use of other more polluted and less sustainable modes due to the cost time, convenience or because people costs to change their habits. To encourage more sustainable transport, firstly we make awareness people of the pollution and to facilitate, encourage and promote most sustainable modes and secondly to penalize most polluting and less sustainable transport.