We have examined the Mg–σ relation for early-type galaxies in the EFAR sample and its dependence on cluster properties. A comprehensive maximum likelihood treatment of the sample selection and measurement errors gives fits to the global Mg–σ relation of Mgb = 0.131 logσ− 0.131 and Mg2 = 0.257 logσ− 0.305. The slope of these relations is 25% steeper than that obtained by most other authors due t...

We present a general method for dynamically posting symmetry breaking constraints during search. The basic idea is very simple. Given any set of symmetry breaking constraints, if during search a symmetry of one of these constraints is entailed and this is consistent with previously posted symmetry breaking constraints, then we post this constraint. We illustrate the method with two examples whe...

This paper is devoted to bilevel optimization, a branch of mathematical programming of both practical and theoretical interest. Starting with a simple example, we proceed towards a general formulation. We then present fields of application, focus on solution approaches, and make the connection with MPECs (Mathematical Programs with Equilibrium Constraints).

Mathematical programs whose formulation is symmetric often take a long time to solve using Branch-and-Bound type algorithms, because of the several symmetric optima. A simple technique used in these cases is to adjoin symmetry breaking constraints to the formulation before solving the problem. These constraints: (a) aim to guarantee that at least one optimum is feasible, whilst making some of t...

Various models that incorporate concepts from Non-Cooperative Game Theory (NCGT) are described in the transport literature. Game Theory provides powerful tools for analysing transport systems, but these tools have some drawbacks that should be recognised. In the current paper we review games that describe transport problems and discuss them within a uniform context. Although the paper does not ...

In the current social, physical, economical and environmental circumstances of scarcity, the design and management of vital lifelines like transportation systems, especially within the metropolitan context, are subject to the implementation of multiple objectives in a unified framework. Thus, one of the most important issues is the identification of optimal trade-offs among crucial objectives b...

Previous approaches for scheduling a league with round-robin and divisional tournaments involved decomposing the problem into easier subproblems. This approach, used to schedule the top Swedish handball league Elitserien, reduces the problem complexity but can result in suboptimal schedules. This paper presents an integrated constraint programming model that allows to perform the scheduling in ...

Symmetry breaking for constraint satisfaction problems (CSPs) has attracted considerable attention in recent years. Various general schemes have been proposed to eliminate symmetries. In general, these schemes may take exponential space or time to eliminate all the symmetries. We identify several classes of CSPs that encompass many practical problems and for which symmetry breaking for various ...

in this paper, the important formation control problem of nonholonomic wheeled mobile robots is investigated via a leader-follower strategy. to this end, the dynamics model of the considered wheeled mobile robot is derived using lagrange equations of motion. then, using adams multi-body simulation software, the obtained dynamics of the wheeled system in matlab software is verified. after that, ...

this study deals with the 3d recovering of magnetic susceptibility model by incorporating the sparsity-based constraints in the inversion algorithm. for this purpose, the area under prospect was divided into a large number of rectangular prisms in a mesh with unknown susceptibilities. tikhonov cost functions with two sparsity functions were used to recover the smooth parts as well as the sharp ...