Claudi Alsina – författare

Solid geometry is the traditional name for what we call today the geometry of three-dimensional Euclidean space. This book presents techniques for proving a variety of geometric results in three dimensions. Special attention is given to prisms, pyramids, platonic solids, cones, cylinders and spheres, as well as many new and classical results. A chapter is devoted to each of the following basic techniques for exploring space and proving theorems: enumeration, representation, dissection, plane sections, intersection, iteration, motion, projection, and folding and unfolding. The book includes a selection of Challenges for each chapter with solutions, references and a complete index. The text is aimed at secondary school and college and university teachers as an introduction to solid geometry, as a supplement in problem solving sessions, as enrichment material in a course on proofs and mathematical reasoning, or in a mathematics course for liberal arts students.

A Cornucopia of Quadrilaterals collects and organizes hundreds of beautiful and surprising results about four-sided figures--for example, that the midpoints of the sides of any quadrilateral are the vertices of a parallelogram, or that in a convex quadrilateral (not a parallelogram) the line through the midpoints of the diagonals (the Newton line) is equidistant from opposite vertices, or that, if your quadrilateral has an inscribed circle, its center lies on the Newton line. There are results dating back to Euclid: the side-lengths of a pentagon, a hexagon, and a decagon inscribed in a circle can be assembled into a right triangle (the proof uses a quadrilateral and circumscribing circle); and results dating to Erdos: from any point in a triangle the sum of the distances to the vertices is at least twice as large as the sum of the distances to the sides. The book is suitable for serious study, but it equally rewards the reader who dips in randomly. It contains hundreds of challenging four-sided problems. Instructors of number theory, combinatorics, analysis, and geometry will find examples and problems to enrich their courses. The authors have carefully and skillfully organized the presentation into a variety of themes so the chapters flow seamlessly in a coherent narrative journey through the landscape of quadrilaterals. The authors' exposition is beautifully clear and compelling and is accessible to anyone with a high school background in geometry.

The authors present twenty icons of mathematics, that is, geometrical shapes such as the right triangle, the Venn diagram, and the yang and yin symbol and explore mathematical results associated with them. As with their previous books (Charming Proofs, When Less is More, Math Made Visual) proofs are visual whenever possible. The results require no more than high-school mathematics to appreciate and many of them will be new even to experienced readers. Besides theorems and proofs, the book contains many illustrations and it gives connections of the icons to the world outside of mathematics. There are also problems at the end of each chapter, with solutions provided in an appendix. The book could be used by students in courses in problem solving, mathematical reasoning, or mathematics for the liberal arts. It could also be read with pleasure by professional mathematicians, as it was by the members of the Dolciani editorial board, who unanimously recommend its publication.

A Panoply of Polygons presents and organizes hundreds of beautiful, surprising and intriguing results about polygons with more than four sides. (A Cornucopia of Quadrilaterals, a previous volume by the same authors, thoroughly explored the properties of four-sided polygons.) This panoply consists of eight chapters, one dedicated to polygonal basics, the next ones dedicated to pentagons, hexagons, heptagons, octagons and many-sided polygons. Then miscellaneous classes of polygons are explored (e.g., lattice, rectilinear, zonogons, cyclic, tangential) and the final chapter presents polygonal numbers (figurate numbers based on polygons). Applications, real-life examples, and uses in art and architecture complement the presentation where many proofs with a visual nature are included.A Panoply of Polygons can be used as a supplement to a high school or college geometry course. It can also be used as a source for group projects or extra-credit assignments. It will appeal, and be accessible to, anyone with an interest in plane geometry. Claudi Alsina and Roger Nelsen are, jointly and individually, the authors of thirteen previous MAA/AMS books. Those books, and this one, celebrate and illuminate the power of visualization in learning, teaching, and creating mathematics.

This book provides an exploration of the mathematics underlying the works of the Catalan architect Antoni Gaudi i Cornet (1852-1926). Illustrated by over 300 graphics and photographs, the text describes the applications of geometry that are found in Gaudí’s buildings. The narrative is further enhanced by numerous ""Math Moments,"" highlighting the mathematics and mathematicians that come to mind when one observes Gaudi's creations. After an opening chapter giving a pictorial overview of Gaudi's work, the book covers topics from two- and three-dimensional geometry such as plane curves, ruled surfaces, ellipsoids, paraboloids, polygons, and polyhedra. Special attention is given throughout to Gaudi's magnum opus, the Basilica de la Sagrada Família. The book finishes with detailed appendices, including a brief biography of the architect as well as supplemental proofs and technical notes to develop ideas from the main text. Suitable for lovers of geometry or architecture, the modest prerequisites mean The Genius of Gaudi can also be used as a supplemental text for a geometry course at the high-school level and above. In addition, it may be enjoyed as a mathematical tour guide for anyone visiting the city of Barcelona.

Sätze und ihre Beweise bilden das Herz der Mathematik. Diese Sammlung bezaubernder Beweise, verblüffender Argumente und überzeugender bildlicher Darstellungen lädt den Leser ein, sich an der Schönheit der Mathematik zu erfreuen, seine Entdeckungen mit anderen zu teilen und bei dem Finden neuer Beweise mitzumachen. Das Buch umfasst folgende Themen: natürliche Zahlen, besondere reelle Zahlen, Punkte in der Ebene, Dreiecke, Quadrate, andere Vielecke, Kurven, Ungleichungen, ebene Parkettierungen, Origami, Beweise mit Färbungen, dreidimensionale Geometrie, usw. Jedes Kapitel endet mit einigen Aufgaben, die den Leser in die Kunst des Auffindens von  bezaubernden Beweisen einbezieht. Es gibt insgesamt über 130 solcher Aufgaben.

Dieses Buch handelt von 20 geometrischen Figuren (Icons), die eine wichtige Rolle bei der Veranschaulichung mathematischer Beweise spielen. Alsina und Nelsen untersuchen die Mathematik, die hinter diesen Figuren steckt und die sich aus ihnen ableiten lässt.Jedem in diesem Buch behandelten Icons ist ein eigenes Kapitel gewidmet, in dem sein Alltagsbezug, seine wesentlichen mathematischen Eigenschaften sowie seine Bedeutung für visuelle Beweise vieler mathematischer Sätze betont werden. Diese Sätze umfassen unter anderem auch klassische Ergebnisse aus der ebenen Geometrie, Eigenschaften der natürlichen Zahlen, Mittelwerte und Ungleichungen, Beziehungen zwischen Winkelfunktionen, Sätze aus der Differenzial- und Integralrechnung sowie Rätsel aus dem Bereich der Unterhaltungsmathematik. Darüber hinaus enthält jedes Kapitel eine Auswahl an Aufgaben, anhand derer die Leser weitere Eigenschaften und Anwendungen der Diagramme erkunden können.Das Buch ist für alle geschrieben, die Freude an der Mathematik haben; Lehrkräfte und Dozenten der Mathematik werden in diesem Buch sehr nützliche Beispiele für Problemlösungen sowie umfangreiches Unterrichts- und Seminarmaterial zu Beweisen und mathematischer Argumentation finden.

The functional equation of associativity is the topic of Abel's first contribution to Crelle's Journal. Seventy years later, it was featured as the second part of Hilbert's Fifth Problem, and it was solved under successively weaker hypotheses by Brouwer (1909), Cartan (1930) and Aczel (1949). In 1958, B Schweizer and A Sklar showed that the “triangular norms” introduced by Menger in his definition of a probabilistic metric space should be associative; and in their book Probabilistic Metric Spaces, they presented the basic properties of such triangular norms and the closely related copulas. Since then, the study of these two classes of functions has been evolving at an ever-increasing pace and the results have been applied in fields such as statistics, information theory, fuzzy set theory, multi-valued and quantum logic, hydrology, and economics, in particular, risk analysis.This book presents the foundations of the subject of associative functions on real intervals. It brings together results that have been widely scattered in the literature and adds much new material. In the process, virtually all the standard techniques for solving functional equations in one and several variables come into play. Thus, the book can serve as an advanced undergraduate or graduate text on functional equations.