ORBi Open Repository and Bibliography
In may 2007, the ULg's Administrative Board (joined in June 2007 by the FUSAGx) decided to create an institutional repository and defined a strong institutional self-archiving policy to increase the visibility, accessibility and impact of the University's publications (Board's decision).
This decision led to the official launch, in November 2008, of the ORBi platform including both the Academic Bibliography and the Institutional Repository of the Wallonia-Europe University Academy.
Business & economic sciences => Quantitative methods in economics & management
Quadratizations of pseudo-Boolean functions - Crama, Yves
A pseudo-Boolean function is a real-valued function of 0-1 variables. Every pseudo-Boolean function can be represented by various analytical expressions, e.g., as a polynomial in its variables, or as a polynomial in its variables and in their Boolean complements, or as a disjunctive form, or as pointwise minimum of a family of affine functions, and so forth.
Motivated by the problem of minimizing pseudo-Boolean functions, we consider yet another class of representations. Namely, we say that g(x,y) is a quadratization of the pseudo-Boolean function f(x) if g(x,y) is a quadratic pseudo-Boolean function of x and of m auxiliary binary variables y...
Revealed preference tests of collectively rational consumption behavior - Crama, Yves
To verify the empirical adequacy of a particular household consumption model, it is important to develop efficient tests did can be applied to real-world data. These tests check whether the observed household behavior is "rational" in the sense that it is consistent with the predictions of the model. In this talk, we present different approaches based on revealed preferences to test collective models of household consumption. Testing collective rationality is computationally difficult (NP-hard). In order to overcome this negative result, we introduce mixed-integer programming formulations which can be used for medium-sized datasets. Next, we propose simulated annealing heuristics, which allow...
Economic Design of Control Charts In Presence of Censored Data - Faraz, Alireza; Heuchenne, Cédric
we present Shewhart type Z ̅ and S2 control charts for monitoring individual or joint shifts in the scale and shape parameters of a Weibull distributed process. The advantage of this method is its ease of use and flexibility for the case where the process distribution is Weibull, although the method can be applied to any distribution. We illustrate the performance of our method through simulation and the application through the use of an actual data set. Our results indicate that Z ̅ and S2 control charts perform well in detecting shifts in the scale and shape parameters. We also...
Quadratic reformulations of nonlinear binary optimization problems - Anthony, Martin; Boros, Endre; Crama, Yves; Gruber, Aritanan
Very large nonlinear unconstrained binary optimization problems arise in a broad array of applications. Several exact or heuristic techniques have proved quite successful for solving many of these problems when the objective function is a quadratic polynomial. However, no similarly efficient methods are available for the higher degree case. Since high degree objectives are becoming increasingly important in certain application areas, such as computer vision, various techniques have been recently developed to reduce the general case to the quadratic one, at the cost of increasing the number of variables. In this paper we initiate a systematic study of these quadratization...
BRAIN TRAINS: Intermodal rail freight transport and hinterland connections A SWOT analysis to assess the Belgian rail practice - Troch, Frank; Vanelslander, Thierry; Belboom, Sandra; Léonard, Angélique; Limbourg, Sabine; Merchan Arribas, Angel; Mostert, Martine; Pauwels, Tom; Vidar, Stevens; Sys, Christa; Tawfik, Christine Maher Fouad; Verhoest, Koen
This paper focuses on transversal research of the role and influences of rail freight transport, as a part of intermodal transport in Belgium. A SWOT analysis of the current situation is conducted, starting from the actual weak usage of this mode of transport. Five different fields have been identified, impacting the economy and society. Each field indicates critical internal strengths and weaknesses for intermodal rail transportation in Belgium, and identifies possible future developments and setbacks. A Delphi-like approach is used, including a heterogeneous panel of experts, discussing and validating the SWOT results. To prioritize the characteristics, a survey on the...