An Invitation to Coarse Groups

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This book lays the foundation for a theory of coarse groups: namely, sets with operations that satisfy the group axioms “up to uniformly bounded error”. These structures are the group objects in the category of coarse spaces, and arise naturally as approximate subgroups, or as coarse kernels. The first aim is to provide a standard entry-level introduction to coarse groups. Extra care has been taken to give a detailed, self-contained and accessible account of the theory. The second aim is to quickly bring the reader to the forefront of research. This is easily accomplished, as the subject is still young, and even basic questions remain unanswered. Reflecting its dual purpose, the book is divided into two parts. The first part covers the fundamentals of coarse groups and their actions. Here the theory of coarse homomorphisms, quotients and subgroups is developed, with proofs of coarse versions of the isomorphism theorems, and it is shown how coarse actions are related to fundamental aspects of geometric group theory. The second part, which is less self-contained, is an invitation to further research, where each thread leads to open questions of varying depth and difficulty. Among other topics, it explores coarse group structures on set-groups, groups of coarse automorphisms and spaces of controlled maps. The main focus is on connections between the theory of coarse groups and classical subjects, including: number theory; the study of bi-invariant metrics on groups; quasimorphisms and stable commutator length; groups of outer automorphisms; and topological groups and their actions. The book will primarily be of interest to researchers and graduate students in geometric group theory, topology, category theory and functional analysis, but some parts will also be accessible to advanced undergraduates.

INVITATION TO QUANTUM MECHANICS

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How do atoms and electrons behave? Are they just like marbles, basketballs, suns, and planets, but smaller? They are not. Atoms and electrons behave in a fashion quite unlike the familiar marbles, basketballs, suns, and planets. This sophomore-level textbook delves into the counterintuitive, intricate, but ultimately fascinating world of quantum mechanics. Building both physical insight and mathematical technique, it opens up a new world to the discerning reader. After discussing experimental demonstrations showing that atoms behave differently from marbles, the book builds up the phenomena of the quantum world — quantization, interference, and entanglement — in the simplest possible system, the qubit. Once the phenomena are introduced, it builds mathematical machinery for describing them. It goes on to generalize those concepts and that machinery to more intricate systems. Special attention is paid to identical particles, the source of considerable student confusion. In the last chapter, students get a taste of what is not treated in the book and are invited to continue exploring quantum mechanics. Problems in the book test both conceptual and technical knowledge, and invite students to develop their own questions. Sample Chapter(s) Chapter 1: "Something Isn't Quite Right" Request Inspection Copy Contents: Synoptic Contents Welcome "Something Isn't Quite Right" What Is Quantum Mechanics About? Forging Mathematical Tools The Quantum Mechanics of Position Solving the Energy Eigenproblem Identical Particles Atoms The Vistas Open to Us Appendix A Significant Figures Appendix B Dimensions Readership: Textbook for second-year undergraduate students in physics, chemistry, engineering, or allied fields, and aimed specifically at the ubiquitous "Modern Physics" course.