Primary Facets Of Order Polytopes

Mixture models on order relations play a central role in recent investigations of transitivity in binary choice data. In such a model, the vectors of choice probabilities are the convex combinations of the characteristic vectors of all order relations of a chosen type. The five prominent types of order relations are linear orders, weak orders, semiorders, interval orders and partial orders. For each of them, the problem of finding a complete, workable characterization of the vectors of probabilities is crucial---but it is reputably inaccessible. Under a geometric reformulation, the problem asks for a linear description of a convex polytope whose vertices are known. As for any convex polytope, a shortest linear description comprises one linear inequality per facet. Getting all of the facet-defining inequalities of any of the five order polytopes seems presently out of reach. Here we search for the facet-defining inequalities which we call primary because their coefficients take only the values -1, 0 or 1. We provide a classification of all primary, facet-defining inequalities of three of the five order polytopes. Moreover, we elaborate on the intricacy of the primary facet-defining inequalities of the linear order and the weak order polytopes

Metric and latticial medians

This paper presents the -linked- notions of metric and latticial medians and it explains what is the median procedure for the consensus problems, in particular in the case of the aggregation of linear orders. First we consider the medians of a v-tuple of arbitrary or particular binary relations.. Then we study in depth the difficult (in fact NP-difficult) problem of finding the median orders of a profile of linear orders. More generally, we consider the medians of v-tuples of elements of a semilattice and we describe the median semilattices, i.e. the semilattices were medians are easily computable.Ce texte présente les notions -reliées- de médianes métriques et latticielles et explique le rôle de la procédure médiane dans les problèmes de consensus, notamment dans le cas de l'agrégation d'ordres totaux.. Après avoir étudié les médianes d'un v-uple de relations binaires arbitraires ou particulières, on étudie en détail le problème -difficile (NP-difficile)- d'obtention des ordres médians d'un profil d'ordres totaux. Plus généralement on considère les médianes de v-uples d'éléments d'un demi-treillis (ou d'un treillis) et l'on décrit les demi-treillis à médianes,i.e. ceux où l'obtention des médianes est aisée

OPTIMIZATION OF RAILWAY TRANSPORTATION HAZMATS AND REGULAR COMMODITIES

Transportation of dangerous goods has been receiving more attention in the realm of academic and scientific research during the last few decades as countries have been increasingly becoming industrialized throughout the world, thereby making Hazmats an integral part of our life style. However, the number of scholarly articles in this field is not as many as those of other areas in SCM. Considering the low-probability-and-high-consequence (LPHC) essence of transportation of Hazmats, on the one hand, and immense volume of shipments accounting for more than hundred tons in North America and Europe, on the other, we can safely state that the number of scholarly articles and dissertations have not been proportional to the significance of the subject of interest. On this ground, we conducted our research to contribute towards further developing the domain of Hazmats transportation, and sustainable supply chain management (SSCM), in general terms. Transportation of Hazmats, from logistical standpoint, may include all modes of transport via air, marine, road and rail, as well as intermodal transportation systems. Although road shipment is predominant in most of the literature, railway transportation of Hazmats has proven to be a potentially significant means of transporting dangerous goods with respect to both economies of scale and risk of transportation; these factors, have not just given rise to more thoroughly investigation of intermodal transportation of Hazmats using road and rail networks, but has encouraged the competition between rail and road companies which may indeed have some inherent advantages compared to the other medium due to their infrastructural and technological backgrounds. Truck shipment has ostensibly proven to be providing more flexibility; trains, per contra, provide more reliability in terms of transport risk for conveying Hazmats in bulks. In this thesis, in consonance with the aforementioned motivation, we provide an introduction into the hazardous commodities shipment through rail network in the first chapter of the thesis. Providing relevant statistics on the volume of Hazmat goods, number of accidents, rate of incidents, and rate of fatalities and injuries due to the incidents involving Hazmats, will shed light onto the significance of the topic under study. As well, we review the most pertinent articles while putting more emphasis on the state-of-the-art papers, in chapter two. Following the discussion in chapter 3 and looking at the problem from carrier company’s perspective, a mixed integer quadratically constraint problem (MIQCP) is developed which seeks for the minimization of transportation cost under a set of constraints including those associating with Hazmats. Due to the complexity of the problem, the risk function has been piecewise linearized using a set of auxiliary variables, thereby resulting in an MIP problem. Further, considering the interests of both carrier companies and regulatory agencies, which are minimization of cost and risk, respectively, a multiobjective MINLP model is developed, which has been reduced to an MILP through piecewise linearization of the risk term in the objective function. For both single-objective and multiobjective formulations, model variants with bifurcated and nonbifurcated flows have been presented. Then, in chapter 4, we carry out experiments considering two main cases where the first case presents smaller instances of the problem and the second case focuses on a larger instance of the problem. Eventually, in chapter five, we conclude the dissertation with a summary of the overall discussion as well as presenting some comments on avenues of future work

The Complexity of Computing Medians of Relations

The Complexity of Computing Medians of Relation

Integrating expert-based objectivist and nonexpert-based subjectivist paradigms in landscape assessment

This thesis explores the integration of objective and subjective measures of landscape aesthetics, particularly focusing on crowdsourced geo-information. It addresses the increasing importance of considering public perceptions in national landscape governance, in line with the European Landscape Convention's emphasis on public involvement. Despite this, national landscape assessments often remain expert-centric and top-down, facing challenges in resource constraints and limited public engagement. The thesis leverages Web 2.0 technologies and crowdsourced geographic information, examining correlations between expert-based metrics of landscape quality and public perceptions. The Scenic-Or-Not initiative for Great Britain, GIS-based Wildness spatial layers, and LANDMAP dataset for Wales serve as key datasets for analysis. The research investigates the relationships between objective measures of landscape wildness quality and subjective measures of aesthetics. Multiscale geographically weighted regression (MGWR) reveals significant correlations, with different wildness components exhibiting varying degrees of association. The study suggests the feasibility of incorporating wildness and scenicness measures into formal landscape aesthetic assessments. Comparing expert and public perceptions, the research identifies preferences for water-related landforms and variations in upland and lowland typologies. The study emphasizes the agreement between experts and non-experts on extreme scenic perceptions but notes discrepancies in mid-spectrum landscapes. To overcome limitations in systematic landscape evaluations, an integrative approach is proposed. Utilizing XGBoost models, the research predicts spatial patterns of landscape aesthetics across Great Britain, based on the Scenic-Or-Not initiatives, Wildness spatial layers, and LANDMAP data. The models achieve comparable accuracy to traditional statistical models, offering insights for Landscape Character Assessment practices and policy decisions. While acknowledging data limitations and biases in crowdsourcing, the thesis discusses the necessity of an aggregation strategy to manage computational challenges. Methodological considerations include addressing the modifiable areal unit problem (MAUP) associated with aggregating point-based observations. The thesis comprises three studies published or submitted for publication, each contributing to the understanding of the relationship between objective and subjective measures of landscape aesthetics. The concluding chapter discusses the limitations of data and methods, providing a comprehensive overview of the research

Market size, competition and the product mix of exporters

Recent empirical evidence has highlighted how the export patterns of multi-product firms dominate world trade flows, and how these multi-product firms respond to different economic conditions across export markets by varying the number of products they export. In this paper, we further analyze the effects of those export market conditions on the relative export sales of those goods: we refer to this as the firm's product mix choice. We build a theoretical model of multi-product firms that highlights how market size and geography (the market sizes of and bilateral economic distances to trading partners) affects both a firm's exported product range and its exported product mix across market destinations. We show how tougher competition in an export market - associated with a downward shift in the distribution of markups across all products sold in the market - induces a firm to skew its export sales towards its best performing products. We find very strong confirmation of this competitive effect for French exporters across export market destinations. Our theoretical model shows how this effect of export market competition on a firm's product mix then translates into differences in measured firm productivity. Thus, a firm operating a given technology will produce relatively more output per worker when it exports to markets with tougher competition. This productivity gain is further compounded by the effect of competition on the mix of exported products.

Advanced Family Law

Meeting proceedings of a seminar by the same name, held July 29-30, 2021

Assessing road network vulnerability: a User Equilibrium interdiction model

Road networks are vulnerable to natural and man-made disruptions. The loss of one or many critical links of the network often leads to increased traffic congestion. Therefore, quantitative models are necessary to identify these critical assets so that actions can be taken by decision makers to mitigate the impact of disruptions. This paper proposes an optimisation model to identify the set of arcs that, when lost, results in the worst congestion under user equilibrium traffic. The model is formulated as a bi-level non-linear problem. The challenging formulation is solved via a customised version of Greedy Randomised Adaptive Search Procedure (GRASP) meta-heuristic. Computational experiments are run on a dataset of artificial grids and managerial insights are provided based on popular Sioux and Berlin network case-studies

New graduate registered nurse practice readiness for Australian healthcare contexts: a collective instrumental case study

For new graduate registered nurses (NGRNs) practice readiness, or the ability to enter the healthcare setting and practice competently as a registered nurse (RN) is essential for safe patient care and meeting the needs of healthcare providers (individuals and institutions) (HCPs). A NGRN's level of practice readiness can affect transition to the RN role, retention rates and patient safety. Studies aimed at exploring the preparation and transition of NGRNs from student to RN suggest that NGRNs are not 'practice ready'. Researchers that have investigated the concept of practice readiness describe it as a multidimensional concept that is poorly defined and shaped by context. Researchers examining the practice readiness of Australian NGRNs have focussed on specific geographic areas and healthcare contexts; undergraduate nurses (UGNs); or involved graduates from other professions. Minimal research has been undertaken to explore the perspectives of healthcare professionals working with NGRNs in Australian healthcare settings across diverse geographic locations. While growing evidence implies that NGRNs are not practice ready, a common understanding of NGRN practice readiness and how practice readiness is achieved, measured and determined remains unclear and variable. As a result, inconsistencies in expectations exist between HCPs, NGRNs and education providers. Such inconsistencies can lead to NGRNs having difficulty meeting HCPs' expectations, adjusting to their new role and providing a safe standard of care. Using a multiple case study approach, the concept of NGRN practice readiness from the perspective of healthcare professionals in Queensland, Australia is explored. Four case studies of healthcare institutions in four different geographic locations were completed. Constructivism and symbolic interactionism were used as the theoretical framework to help explain how individual HCP's perception, context and practice intersect to conceptualise descriptions and meanings of NGRN practice readiness. Methods employed for data generation and collection included individual and focus group interviews; document review; field notes; and memos. Individual and cross-case analyses were conducted using selected grounded theory methods of coding and categorising of data; concurrent data collection and analysis; constant comparative analysis; and memo writing. Data from each case were integrated and interpreted against the research questions to provide an in-depth understanding of NGRN practice readiness. The cross-case analysis identified four major categories: Dominance of context; Determining practice readiness; Defining practice readiness; and Developing practice readiness. The findings highlight how decisions about practice readiness are informed by HCP's personal and professional context. Practice readiness is defined as a multidimensional concept encompassing personal, clinical, industry and professional capabilities. Findings indicate that acquiring the required level of practice readiness relies on factors present in a NGRN's pre- and post-registration education and clinical experiences and occurs across a 4-year continuum of learning that includes a NGRN's first year of practice, where the NGRN makes the final transition from student to professional RN. Recommendations from this study will inform policies and practices that aim to improve NGRN practice readiness and consequently their transition, integration and retention in the healthcare workforce

Multi-attribute value measurement and economic paradigms in environmental decision making

Bibliography: p. 219-228.The two environmental decision-making approaches of environmental economics (EE) valuation and multi-criteria decision analysis (MCDA) differ fundamentally in their underlying philosophies and approach; hence they are characterised as paradigms. The EE paradigm includes the idea that, if appropriate prices can be found and implemented for goods not normally traded on the market, then the market mechanism will efficiently distribute resources and decisions are therefore based on the concepts of individual willingness to pay and consumer sovereignty. That an efficient market is not necessarily equitable or sustainable has long been acknowledged, but EE adjustments are subject to theoretical and methodological problems. The MCDA paradigm is based on the idea that values and preferences should be examined and constructed through interaction between workshop participants and the analyst, given basic measurement theory axioms. Various EE and MCDA methods have been devised for measuring value in different contexts, some of which were applied, in the context of environmental (particularly water resources) management, in six action research case studies. The EE methods were contingent behaviour valuation, the contingent valuation method, conjoint analysis and the travel cost method. The MCDA method was a version of the simple multi-attribute rating technique (called SMARTx). In the SMARTx cases, applying a group-value sharing model during a series of workshops, stakeholders rated the effect of alternatives on a number of environmental, social and economic attributes directly or using value functions and gave weights to criteria. Indirect compensatory values of one criterion in terms of another were determined. In the EE cases, survey respondents were asked their travel costs, preference for multi-attribute profiles and willingness to pay for alternatives. Total and average willingness to pay for an amenity, its attributes or changes in environmental quality were determined. The practical and theoretical implications of applying the different methods were examined and compared in terms of four metacriteria: resonance with and validity within the prevailing political and decision-context, general validity and reliability, ability to include equity and sustainability criteria and practicality