The Shapley value without efficiency and additivity

We provide a new characterization of the Shapley value neither using the efficiency axiom nor the additivity axiom. In this characterization, efficiency is replaced by the gain-loss axiom (Einy and Haimanko, 2011), i.e., whenever the total worth generated does not change, a player can only gain at the expense of another one. Additivity and the equal treatment axiom are substituted by fairness (van den Brink, 2001) or differential marginality (Casajus, 2011), where the latter requires equal productivity differentials of two players to translate into equal payoff differentials. The third axiom of our characterization is the standard dummy player axiom.     

On an axiomatization of the banzhaf value without the additivity axiom

We prove that the Banzhaf value is a unique symmetric solution having the dummy player property, the marginal contributions property introduced by Young (1985) and satisfying a very natural reduction axiom of Lehrer (1988).     

An introduction to the Ribe program

We survey problems, results, ideas, and recent progress in the Ribe program. The goal of this research program, which is motivated by a classical rigidity theorem of Martin Ribe, is to obtain structural results for metric spaces that are inspired by the local theory of Banach spaces. We also present examples of applications of the Ribe program to several areas, including group theory, theoretical computer science, and probability theory.     

An introduction to the k-defect polynomials

The 0-defect polynomial of a graph is just the chromatic polynomial. This polynomial has been widely studied in the literature. Yet little is known about the properties of k-defect polynomials of graphs in general, when 0 < k ≤ |E(G)|. In this survey we give some properties of k-defect polynomials, in particular we highlight the properties of chromatic polynomials which also apply to k-defect polynomials. We discuss further research which can be done on the k-defect polynomials.     

An introduction to timetabling

A huge variety of timetabling models have been described in the OR literature; they range from the weekly timetable of a school to the scheduling of courses or exams in a university. Graphs and networks have proven to be useful in the formulation and solution of such problems. Various models will be described with an emphasis on graph theoretical models.     

An introduction to the perplex number system

The perplex number system is a generalization of the abstract logical relationships among electrical particles. The inferential logic of the new number system is homologous to the inferential logic of the progression of the atomic numbers. An electrical progression is defined categorically as a sequence of objects with teridentities. Each identity infers corresponding values of an integer, units and a correspondence relation between each unit and its integer. Thus, in this logical system, each perplex numeral contains an exact internal representational structure; it carries an internal message. This structure is a labeled bipartite graph that is homologous to the internal electrical structure of a chemical atom. The formal logical operations are conjunctions and disjunctions. Combinations of conjunctions and disjunctions compose the spatiality of objects. Conjunctions may include the middle term of pairs of propositions with a common term, thereby creating new information. The perplex numerals are used as a universal source of diagrams.The perplex number system, as an abstract generalization of concrete objects and processes, constitutes a new exact notation for chemistry without invoking alchemical symbols. Practical applications of the number system to concrete objects (chemical elements, simple ions and molecules, and the perplex isomers, ethanol and dimethyl ether) are given. In conjunction with the real number system, the relationships between the perplex number system and scientific theories of concrete systems (thermodynamics, intra-molecular dynamics, molecular biology and individual medicine) are described.     

An introduction to nonlinear dynamics

This paper presents a brief introduction to topological and analytical aspects of nonlinear dynamics. Competing attractors in phase space are described, and the vector field viewpoint is outlined. Poincaré mapping techniques for driven oscillators are presented, and the use of smoothed variational equations in the Van der Pol plane is illustrated by a study of Duffing's equation. The location of domains of attraction by mapping techniques is described drawing on the recent contributions of Hayashi on the subharmonic resonances of driven oscillators.     

An introduction to Minkowski geometries

The fundamental ideas of Minkowski geometries are presented. Learning about Minkowski geometries can sharpen our students’ understanding of concepts such as distance measurement. Many of its ideas are important and accessible to undergraduate students. Following a brief overview, distance and orthogonality in Minkowski geometries are thoroughly discussed and many illustrative examples and applications are supplied. Suggestions for further study of these geometries are given. Indeed, Minkowski geometries are an excellent source of topics for undergraduate research and independent study.     

An introduction to preconvexity spaces

Axioms are given for a preconvexity space and certain consequences obtained. In particular, it is shown that in a very natural way, a preconvexity on a space yields an abstract convexity space in much the same manner as a proximity yields a topological space. This revised version was published online in June 2006 with corrections to the Cover Date.     

An introduction to mathematical physiology and biology

Book Review

An introduction to mathematical physiology and biologyJ. Mazumdar: Cambridge University Press, 1989, xi + 208pp., £27.50 (hardback), £9.95 (paperback)     

Large deviations: An introduction to 2007 Abel prize

2007 Abel prize has been awarded to S R S Varadhan for creating a unified theory of large deviations. We attempt to give a flavour of this branch of probability theory, highlighting the role of Varadhan.     

An introduction to the analysis of approximation algorithms

Approximation algorithms may be inevitable choice when it comes to the solution of difficult combinatorial problems. The mathematical analysis of approximation algorithms can lead to various types of results. In this introductory paper, these various possibilities are illustrated on an example taken from scheduling theory.