Minmax regret combinatorial optimization problems: an Algorithmic Perspective

Candia-Vejar, A (reprint author), Univ Talca, Modeling & Ind Management Dept, Curico, Chile.Uncertainty in optimization is not a new ingredient. Diverse models considering uncertainty have been developed over the last 40 years. In our paper we essentially discuss a particular uncertainty model associated with combinatorial optimization problems, developed in the 90's and broadly studied in the past years. This approach named minmax regret (in particular our emphasis is on the robust deviation criteria) is different from the classical approach for handling uncertainty, stochastic approach, where uncertainty is modeled by assumed probability distributions over the space of all possible scenarios and the objective is to find a solution with good probabilistic performance. In the minmax regret (MMR) approach, the set of all possible scenarios is described deterministically, and the search is for a solution that performs reasonably well for all scenarios, i.e., that has the best worst-case performance. In this paper we discuss the computational complexity of some classic combinatorial optimization problems using MMR. approach, analyze the design of several algorithms for these problems, suggest the study of some specific research problems in this attractive area, and also discuss some applications using this model

Production of subject-verb agreement, tense, mood, and negation in Italian agrammatic aphasia

Impaired (morpho)syntactic production is the hallmark of agrammatic aphasia. Several hypotheses have been proposed to account for agrammatic production, which often make different predictions. The Distributed Morphology Hypothesis (DMH) (Wang et al., 2014) posits that categories involving inflectional alternations are impaired in agrammatism. The Tense Underspecification Hypothesis (TUH) (Wenzlaff & Clahsen, 2004, 2005) states that what is impaired (\u201cunderspecified\u201d) is tense; subject-verb agreement and mood are well-preserved. The Interpretable Features\u2019 Impairment Hypothesis (IFIH) (Fyndanis et al., 2012) predicts categories involving integration processes (e.g., tense, mood, negation) to be more impaired than categories that do not involve integration processes (e.g., agreement). The Tree Pruning Hypothesis (TPH) (Friedmann & Grodzinsky, 1997) states that the syntactic tree is pruned at a specific node, usually tense, with all nodes/categories above the pruning site deleted/inaccessible and all nodes below intact. To reliably test these accounts, one should test agrammatic speakers on a wide range of (morpho)syntactic phenomena/categories. In this study, we investigate the ability of Italian-speaking agrammatic individuals to produce subject-verb agreement, tense, mood, and sentential negation. A sentence completion task (SCT) tapping agreement and tense, a SCT assessing mood, and a constituent ordering task tapping negation were administered to eight native speakers of Italian with chronic agrammatic aphasia and eight controls. Results are presented in Table 1. The control group performed better than the aphasic group on all four conditions. Both groups showed similar patterns of performance, with better performance on agreement and tense than on mood. Negation was better preserved than agreement, tense, and mood in the aphasic group, but in the control group negation was not different from any other category. At the individual level, five agrammatic participants exhibited the same pattern of performance (agreement/tense/negation>mood). At the group level, the results of the agrammatic participants are not consistent with any of the hypotheses discussed here. Contrary to the TUH, participants performed better on tense than on mood. The DMH cannot explain the observed, selective impairment of categories involving inflectional alternations (tense/agreement>mood). Results do not support the TPH, as the higher the category in the syntactic hierarchy (Neg>T(future/past)>M) (Cinque, 1999; Zanuttini, 2001), the better the performance of agrammatic participants. Lastly, results are at odds with the IFIH, because negation (+integration processes) is better preserved than agreement (-integration processes). Analogous results are observed at the individual level. None of the available hypotheses can account for the patterns of performance of all the agrammatic participants. Their results, together with the production results of other agrammatic speakers in the literature, show that all possible patterns can be observed in agrammatism, and that a unitary account of the disorder is unlikely to succeed. We suggest that subject-specific characteristics (e.g., site/type/volume of brain damage, type/severity of language impairment, education, age) and language-specific properties of functional categories (e.g., syntactic hierarchy, interpretability/involvement of integration processes, frequency) may interact in determining the way in which (morpho)syntactic impairments manifest themselves across agrammatic speakers and languages

Instrument for critical analysis of research reports : thesis and dissertations.

Objetivo: Este artigo tem como objetivo apresentar um instrumento de an?lise cr?tica de um tipo espec?fico de relat?rios de pesquisa: teses e disserta??es. Metodologia: Trata-se de um instrumento desenvolvido para realiza??o de uma atividade da disciplina Metodologia de Pesquisa do Programa de P?s-Gradua??o em Gest?o & Organiza??o do Conhecimento da Universidade Federal de Minas Gerais (PPGGOC/UFMG), no primeiro semestre de 2019. A finalidade do instrumento foi analisar a ader?ncia de uma pesquisa cient?fica ?s recomenda??es de Creswell (2014) e outras obras que abordam a metodologia cient?fica. ? composto por nove itens, subdivididos em 67 crit?rios, em formato de perguntas. Para avalia??o, em cada crit?rio ? necess?ria uma marca??o em uma escala do tipo Likert, de 5 pontos, ou seja, o valor 1 ? correspondente ? apresenta??o mais fraca do crit?rio e o valor 5, ? mais forte. Como recurso alternativo, foi inserida no instrumento a op??o ?N?o se aplica (N/A)? para aqueles crit?rios em que o avaliador entende que n?o condiz com a proposta estrutural da pesquisa. Resultados: Ap?s o relato das bases para o desenvolvimento e exposi??o do instrumento, o artigo apresenta seu teste por meio da sua aplica??o na avalia??o de uma tese e de uma disserta??o. Conclus?es: Conclui-se que o instrumento se mostrou adequado para a finalidade proposta, avalia??o de relat?rios de pesquisa de teses e disserta??es, com a recomenda??o de que o estilo do autor e a especificidade de cada investiga??o devam ser levados em considera??o.Objective: this article aims to present a tool for critical analysis of a specific type of research report: theses and dissertations. Methods: this instrument was developed to carry out an activity in the Scientific Methodology course of the Postgraduate Program in Management & Knowledge Organization at the Federal University of Minas Gerais (PPGGOC/UFMG), in the first semester of 2019. The purpose of the instrument was to analyze the adherence of a scientific research to the recommendations of Creswell (2014) and other works on scientific methodology. It consists of 9 items, subdivided into 67 criteria, in the form of questions. For evaluation, each criterion is rated on a 5-point Likert-type scale, with a value of 1 2 Encontros Bibli: revista eletr?nica de biblioteconomia e ci?ncia da informa??o, Florian?polis, v. 26, p. 01-25, 2021. Universidade Federal de Santa Catarina. ISSN 1518-2924. DOI: https://doi.org/10.5007/1518-2924.2021.e78678 corresponding to the less precise presentation of the criterion and a value of 5 to the more accurate presentation. The option ?Not applicable (N / A)? was inserted in the instrument for those criteria in which the evaluator believes that it does not match the structural proposal of the research. Results: After describing the basis for its development, the instrument is presented. Next it was tested through the evaluation of a doctoral dissertation and a master thesis. Conclusions: Results show on that the instrument was adequate for the purpose proposed, that is, the evaluation of research reports of theses and dissertations, with the recommendation that the style and specificity of each investigation must be taken into account

Progress on lead-free metal halide perovskites for photovoltaic applications: a review

ABSTRACT: Metal halide perovskites have revolutionized the field of solution-processable photovoltaics. Within just a few years, the power conversion efficiencies of perovskite-based solar cells have been improved significantly to over 20%, which makes them now already comparably efficient to silicon-based photovoltaics. This breakthrough in solution-based photovoltaics, however, has the drawback that these high efficiencies can only be obtained with lead-based perovskites and this will arguably be a substantial hurdle for various applications of perovskite-based photovoltaics and their acceptance in society, even though the amounts of lead in the solar cells are low. This fact opened up a new research field on lead-free metal halide perovskites, which is currently remarkably vivid. We took this as incentive to review this emerging research field and discuss possible alternative elements to replace lead in metal halide perovskites and the properties of the corresponding perovskite materials based on recent theoretical and experimental studies. Up to now, tin-based perovskites turned out to be most promising in terms of power conversion efficiency; however, also the toxicity of these tin-based perovskites is argued. In the focus of the research community are other elements as well including germanium, copper, antimony, or bismuth, and the corresponding perovskite compounds are already showing promising properties. GRAPHICAL ABSTRACT: [Image: see text

A Lower Bound to the Set Partitioning Problem with Side Constraints

A Lagrangean relaxation approach is proposed to provide a lower bound on the optimal solution of the set partitioning problem with side constraints, which is a general methodology to solve a combinatorial optimization problem. This Lagrangean relaxation approach is accomplished by a subgradient optimization procedure which solves at each iteration a special 0-1 knapsack problem. The approach seems to be promising since it produces feasible integer solutions to the side constraints that can hopefully be the optimal solution to most of the instances of the set partitioning problem with side constraint