Coset enumeration, based on the methods described by Todd & Coxeter, is one of the basic tools for investigating nitely presented groups. The process is not well understood, and various pathological presentations of, for example, the trivial group have been suggested as challenge problems. Here we consider one such presentation. We show that it is much easier than it rst appears, albeit at the ...

We describe a class of groups with the property that the finite ones among them are precisely the complex reflection groups of rank two. This situation is reminiscent of Coxeter groups, among which the finite ones are precisely the real reflection groups. We also study braid relations between complex reflections and indicate connections to an axiomatic study of root systems and to the Shephard-...

Simon’s (1955) famous paper was one of the first to cast doubt on the validity of rational choice theory; it has been supplemented by many more papers in the last three and a half decades. Nevertheless, rational choice theory plays a crucial role in classical and neoclassical economic theory, which presumes a completely rational agent. The central points characterizing such an agent are: (1) Th...

A packing of spherical caps on the surface of a sphere (that is, a spherical code) is called rigid or jammed if it is isolated within the space of packings. In other words, aside from applying a global isometry, the packing cannot be deformed. In this paper, we systematically study the rigidity of spherical codes, particularly kissing configurations. One surprise is that the kissing configurati...

We present a new algorithm obtained by changing the search directions in the algorithm given in [8]. This algorithm is based on a new technique for finding the search direction and the strategy of the central path. At each iteration, we use only the full Nesterov-Todd (NT)step. Moreover, we obtain the currently best known iteration bound for the infeasible interior-point algorithms with full NT...

An infeasible interior-point algorithm for mixed symmetric cone linear complementarity problems is proposed. Using the machinery of Euclidean Jordan algebras and Nesterov-Todd search direction, the convergence analysis of the algorithm is shown and proved. Moreover, we obtain a polynomial time complexity bound which matches the currently best known iteration bound for infeasible interior-point ...

Which characteristics of managers ’ information search behavior distinguish successful from less successful use of (executive) information systems. 3 This article addresses this question by employing a new process-tracing approach in an exploratory laboratory study with fifty managers as participants. Building upon and extending existing theoretical models, three main factors are identified rel...

http://dx.doi.org/10.1016/j.paid.2014.03.032 0191-8869/ 2014 Published by Elsevier Ltd. q Project supported by National Science Center Poland (N N106 291239) to Lukasz Kaczmarek. Todd Kashdan was funded by the Center for the Advancement of Well-Being, George Mason University. ⇑ Corresponding author. Address: Department of Psychology, MS 3F5, George Mason University, Fairfax, VA 22030, United St...

Economists have long been interested in the performance of specific regional economies and the forces driving a particular economy. The McCarthy–Steindel and Kuttner– Sbordone studies of the New York metropolitan area follow in this tradition. McCarthy and Steindel focus on documenting the performance of New York relative to that of the nation and distinguishing the roles of national and region...

An interior point method (IPM) defines a search direction at each interior point of the feasible region. These search directions form a direction field, which in turn gives rise to a system of ordinary differential equations (ODEs). Thus, it is natural to define the underlying paths of the IPM as solutions of the system of ODEs. In [32], these off-central paths are shown to be well-defined anal...