Pareto Local Optima of Multiobjective NK-Landscapes with Correlated Objectives

International audienceIn this paper, we conduct a fitness landscape analysis for multiobjective combinatorial optimization, based on the local optima of multiobjective NK-landscapes with objective correlation. In single-objective optimization, it has become clear that local optima have a strong impact on the performance of metaheuristics. Here, we propose an extension to the multiobjective case, based on the Pareto dominance. We study the co-influence of the problem dimension, the degree of non-linearity, the number of objectives and the correlation degree between objective functions on the number of Pareto local optima

On the Effect of Connectedness for Biobjective Multiple and Long Path Problems

Recently, the property of connectedness has been claimed to give a strong motivation on the design of local search techniques for multiobjective combinatorial optimization (MOCO). Indeed, when connectedness holds, a basic Pareto local search, initialized with at least one non-dominated solution, allows to identify the efficient set exhaustively. However, this becomes quickly infeasible in practice as the number of efficient solutions typically grows exponentially with the instance size. As a consequence, we generally have to deal with a limited-size approximation, where a good sample set has to be found. In this paper, we propose the biobjective multiple and long path problems to show experimentally that, on the first problems, even if the efficient set is connected, a local search may be outperformed by a simple evolutionary algorithm in the sampling of the efficient set. At the opposite, on the second problems, a local search algorithm may successfully approximate a disconnected efficient set. Then, we argue that connectedness is not the single property to study for the design of local search heuristics for MOCO. This work opens new discussions on a proper definition of the multiobjective fitness landscape.Comment: Learning and Intelligent OptimizatioN Conference (LION 5), Rome : Italy (2011

Managing Cow’s Milk Protein Allergy in Indonesia:A Cost-effectiveness Analysis of Hypoallergenic Milk Formulas from the Private Payers’ Perspective

Background: Cow’s milk protein allergy is very common in early childhood. Extensively hydrolyzed formulas are recommended in the first-line management of cow’s milk protein allergy in non-breastfed children. Choice of formulas should be informed by efficacy and cost data. Objectives: This study aims to compare the cost-effectiveness of extensively hydrolyzed casein formula with Lacticaseibacillus rhamnosus Gorbach Goldin (EHCF+LGG), extensively hydrolyzed whey formula (EHWF), amino acid formula, and soy formula in the first-line management of cow’s milk protein allergy in non-breastfed children in Indonesia. Methods: A trial-based decision analytic cohort model was adapted to simulate the occurrence of cow’s milk protein allergy symptoms or being symptom free. The model was based on a prospective nonrandomized study that followed up children for 36 months. Costs and health consequences were discounted at 3% annually. Resources required to manage cow’s milk protein allergy and unit costs for clinical appointments and exams were based on a panel of 15 clinicians, from a private payers’ perspective. Other unit costs were based on publicly available national data. Results were reported as cost per additional child free from allergic manifestations or per additional immunotolerant child at 3 years, and per life-years under the same conditions. Uncertainty was assessed using deterministic and probabilistic sensitivity analysis. Results: Children receiving EHCF+LGG were associated with more symptom-free time, a higher probability of cow’s milk tolerance at 3 years, and lower healthcare resources and transportation use when compared with children receiving other formulas (with 38%-49% lower costs). Formula costs were lower for soy, but EHCF+LGG was predicted to save 9% and 54% of overall costs compared with extensively hydrolyzed whey formula and amino acid formula, respectively. Results were robust to sensitivity analyses. Conclusion: Use of EHCF+LGG resulted in more symptom-free time and the highest 3-year probability of cow’s milk tolerance. It also led to healthcare resource and transportation savings when compared with other hypoallergenic milk formulas. Soy formula remained an alternative if formula price represents a major constraint

Vector bundles on the projective line and finite domination of chain complexes

Finitely dominated chain complexes over a Laurent polynomial ring in one indeterminate are characterised by vanishing of their Novikov homology. We present an algebro-geometric approach to this result, based on extension of chain complexes to sheaves on the projective line. We also discuss the K-theoretical obstruction to extension.Comment: v1: 11 page

Ownership and control in a competitive industry

We study a differentiated product market in which an investor initially owns a controlling stake in one of two competing firms and may acquire a non-controlling or a controlling stake in a competitor, either directly using her own assets, or indirectly via the controlled firm. While industry profits are maximized within a symmetric two product monopoly, the investor attains this only in exceptional cases. Instead, she sometimes acquires a noncontrolling stake. Or she invests asymmetrically rather than pursuing a full takeover if she acquires a controlling one. Generally, she invests indirectly if she only wants to affect the product market outcome, and directly if acquiring shares is profitable per se. --differentiated products,separation of ownership and control,private benefits of control

On the performance of local search for the biobjective traveling salesman problem

SCOPUS: ar.kinfo:eu-repo/semantics/publishe