Whirl Of The Wheel

Three children whirl back in time through an enchanted potter's wheel into the reality of evacuation in 1940s Britain. Connie, her brother Charlie-Mouse, and school pest Malcolm are drawn into dangers on the homefront and towards a military operations secret that will save their home. Suggested level: primary, intermediate.

Handbook of Combinatorics

This book is about the perils and pitfalls of the busy mind. Busyness not only challenges our mental and physical health; there are also the subliminal messages that come hidden within the concession to the demands of busyness. This book asks the reader to view the whirl going on in the world today as though it were a stage set, and you are the director as well as one of the actors in the drama. The stage set device is a way to get a fresh and, hopefully, a refreshing perspective on the whirligig merry-go-round that is the busy whirl happening on the world stage today. The movement of the book takes the reader from an unreflective absorption in the whirl of time to a standpoint of spacious clarity, a place that allows one to see clearly what is really going on.

Handbook of Combinatorics, Volume 1 focuses on basic methods, paradigms, results, issues, and trends across the broad spectrum of combinatorics. The selection first elaborates on the basic graph theory, connectivity and network flows, and matchings and extensions. Discussions focus on stable sets and claw free graphs, nonbipartite matching, multicommodity flows and disjoint paths, minimum cost circulations and flows, special proof techniques for paths and circuits, and Hamilton paths and circuits in digraphs. The manuscript then examines coloring, stable sets, and perfect graphs and embeddings and minors. The book takes a look at random graphs, hypergraphs, partially ordered sets, and matroids. Topics include geometric lattices, structural properties, linear extensions and correlation, dimension and posets of bounded degree, hypergraphs and set systems, stability, transversals, and matchings, and phase transition. The manuscript also reviews the combinatorial number theory, point lattices, convex polytopes and related complexes, and extremal problems in combinatorial geometry. The selection is a valuable reference for researchers interested in combinatorics.

The study of matroids is a branch of discrete mathematics with basic links to graphs, lattices, codes, transversals, and projective geometries. Matroids are of fundamental importance in combinatorial optimization and their applications extend into electrical engineering and statics. This incisive survey of matroid theory falls into two parts: the first part provides a comprehensive introduction to the basics of matroid theory while the second treats more advanced topics. The book contains over five hundred exercises and includes, for the first time in one place, short proofs for most of the subjects' major theorems. The final chapter lists sixty unsolved problems and details progress towards their solutions.