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

Local search for the surgery admission planning problem

We present a model for the surgery admission planning problem, and a meta-heuristic algorithm for solving it. The problem involves assigning operating rooms and dates to a set of elective surgeries, as well as scheduling the surgeries of each day and room. Simultaneously, a schedule is created for each surgeon to avoid double bookings. The presented algorithm uses simple Relocate and Two-Exchange neighbourhoods, governed by an iterated local search framework. The problem's search space associated with these move operators is analysed for three typical fitness surfaces, representing different compromises between patient waiting time, surgeon overtime, and waiting time for children in the morning on the day of surgery. The analysis shows that for the same problem instances, the different objectives give fitness surfaces with quite different characteristics. We present computational results for a set of benchmarks that are based on the admission planning problem in a chosen Norwegian hospital

Biostratigraphy of large benthic foraminifera from Hole U1468A (Maldives): A CT-scan taxonomic approach

Large benthic foraminifera are important components of tropical shallow water carbonates. Their structure, developed to host algal symbionts, can be extremely elaborate and presents stratigraphically-significant evolutionary patterns. Therefore their distribution is important in biostratigraphy, especially in the Indo-Pacific area. To provide a reliable age model for two intervals of IODP Hole U1468A from the Maldives Inner-Sea, large benthic foraminifera have been studied with computed tomography. This technique provided 3D models ideal for biometric-based identifications, allowing the upper interval to be placed in the late middle-Miocene and the lower interval in the late Oligocene

The stratigraphic response to the Oligo-Miocene extension in the western Mediterranean from observations on the Sardinia graben system (Italy)

Abstract. – The Sardinian Cainozoic rifted basin is a useful model for studying the stratigraphic response to the Oligo- Miocene structural extension in the western Mediterranean because it allows precise observations on the relationship between sedimentation and normal faulting based on outcrops and seismic reflection data. The purpose of this paper, essentially of stratigraphic nature is to propose a chronology as precise as possible of the tectonic events and of the sedimentary formations. Indeed the tectono-sedimentary framework is complex, characterized by an extreme facies variability, from continental to marginal transitional and to marine environments (shallow-water, hemipelagic). Rifting, active calc-alkaline volcanism and sea-level changes caused rapid physiographical evolution, which controlled progressive marine ingression. New chrono-biostratigraphical data presented in this paper allow correlating the sequences, defining their environment and depth of deposition and specifying precisely the timing of pre-, syn-, and post-rift stages in the Oligo-Miocene graben system. In southwestern Sardinia during the middle-late Eocene, after the Pyrenean phase, a continental graben (Cixerri), W-E oriented, preceded the Oligo-Miocene extension, which reactivated inherited Eocene and Palaeozoic faults. The calc-alkaline volcanic activity ranging from 32 to 13 Ma, provides a good estimate for the time span of the west-dipping Apenninic subduction responsible for the continental extension and the oceanic accretion in the western Mediterranean. In Sardinia the Oligo-Miocene extensional tectonics started in a continental environment, preceding the earliest calc-alkaline volcanic products (32 Ma). The marine ingression is dated to the late Chattian-Aquitanian interval and corresponds to a rapid deepening of the Oligo-Miocene graben system of tectonic origin. The end of the rifting i.e. the end of normal faulting activity is pre-middle Burdigalian in age. When Sardinia was in the post-rift stage, extension continued until late Burdigalian – Langhian in the Algero-Provençal basin with oceanic accretion and rotation of the Corsica-Sardinia block (CSB)

Hypervolume-Based Multi-Objective Path Relinking Algorithm

Abstract. This paper presents a hypervolume-based multi-objective path relinking algorithm for approximating the Pareto optimal set of multi-objective combinatorial optimization problems. We focus on integrating path relinking techniques within a multi-objective local search as an initialization function. Then, we carry out a range of experiments on bi-objective flow shop problem and bi-objective quadratic assignment problem. Experimental results and a statistical comparison are reported in the paper. In comparison with the other algorithms, one version of our proposed algorithm is very competitive. Some directions for future research are highlighted

Fitness Landscape of the Factoradic Representation on the Permutation Flowshop Scheduling Problem

International audienceBecause permutation problems are particularly challenging to model and optimise, the possibility to represent solutions by means of factoradics has recently been investigated, allowing algorithms from other domains to be used. Initial results have shown that methods using factoradics can efficiently explore the search space, but also present difficulties to exploit the best areas. In the present paper, the fitness landscapeof the factoradic representation and one of its simplest operator is studied on the Permutation Flowshop Scheduling Problem (PFSP). Theanalysis highlights the presence of many local optima and a high ruggedness, which confirms that the factoradic representations is not suited for local search. In addition, comparison with the classic permutation representation establishes that local moves on the factoradic representationare less able to lead to the global optima on the PFSP. The study ends by presenting directions for using and improving the factoradic representation