Browsing by Author "Gutierrez, Gabriel"

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    A branch and cut algorithm for the hierarchical network design problem
    (ELSEVIER SCIENCE BV, 2010) Obreque, Carlos; Donoso, Macarena; Gutierrez, Gabriel; Marianov, Vladimir
    The Hierarchical Network Design Problem consists of locating a minimum cost bi-level network on a graph. The higher level sub-network is a path visiting two or more nodes. The lower level sub-network is a forest connecting the remaining nodes to the path. We optimally solve the problem using an ad hoc branch and cut procedure. Relaxed versions of a base model are solved using an optimization package and, if binary variables have fractional values or if some of the relaxed constraints are violated in the solution, cutting planes are added. Once no more cuts can be added. branch and bound is used. The method for finding valid cutting planes is presented. Finally, we use different available test instances to compare the procedure with the best known published optimal procedure, with good results. In none of the instances we needed to apply branch and bound, but only the cutting planes. (C) 2008 Elsevier B.V. All rights reserved.
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    Comparing degrees of 'publicness' and 'privateness' in school systems: the development and application of a public-private index
    (Routledge Journals, Taylor & Francis LTD, 2022) Gutierrez, Gabriel; Lupton, Ruth; Carrasco Rozas, Alejandro Javier; Rasse Figueroa, Alejandra Paz; CEDEUS (Chile)
    The process of privatising services historically provided by the state has blurred the boundaries between what is considered to be 'private' and 'public'. However, few efforts have been made in the educational arena to develop tools to measure this process. Most of the previous research has relied on narrow definitions about what is private and what is public. This work proposes a tool to measure the degree of publicness-privateness of school systems, avoiding binary separation of the concepts. We develop an index and test this tool in two different landscapes: London and Santiago. In these cases, it serves to illustrate major changes in the levels of public-private participation in both school systems, reflecting differences between the systems and over time. We conclude that the index has potential for development and use in the analysis of public and private dimensions in education in broader international contexts.