## Recent book reviews

Five recent book reviews

## Advances in Algebra and Combinatorics

Author(s):
K. P. Shum et al., Eds.
Publisher:
World Scientific, New Jersey
Year:
2008
ISBN:
978-981-279-000-2
Price (tentative):
US-$145 Short description: This volume consists of a selection of lectures presented at the Second International Congress in Algebra and Combinatorics held in July 2007 in Guangzhou, Beijing, and Xian, China. MSC main category: 05 Combinatorics Review: There are 22 papers in the volume. It is not possible to list all of them here but let us mention papers on Quantum polynomials (V. A. Artamonov), Gröbner-Shirshov bases (L. A. Bokut and Y. Q. Chen) and the application of Gröbner-Shirshov bases to Normal Forms of Coxeter groups (D. Lee). There are also papers on Paper-folding, polygons, complete symbols and the Euler quotient function (P. Hilton, J. Pedersen and B. Walden), Irreducible subalgebras of Matrix Weyl Algebras (P. S. Kolesnikov) and Conformal Field Theory and Modular Forms (K. Ueno). M. Jambu contributed a paper on Koszul Algebra and Hyperplane Arrangements and J. Fountain and V. Gould present a paper on Stability of the Theory of Existentially Closed S-Acts over a Right Coherent Monoid S. There are also papers on hyperidentites and hypersubstitutions, various aspects of group theory and so on. Reviewer: J. Tuma (Prague) ## Complex Analysis with Mathematica + CD Author(s): W. T. Shaw Publisher: Cambridge University Press, Cambridge Year: 2006 ISBN: ISBN 978-0-521-83626-5 Price (tentative): £ 45 Short description: The first version (2006) of the book was announced in the EMS Newsletter June 2006, No. 60, p. 8, and praised there by Roger Penrose and then voted one of Choice magazine’s Outstanding Academic Titles for 2007. The current reprinted edition 2008 includes some corrections and a CD updated for the newer Version 6 of Mathematica®. MSC main category: 30 Functions of a complex variable Review: The book presents complex numbers and complex analysis with many applications in a state-of-the-art computational environment. It offers enrichment of the standard complex analysis course: Newton-Raphson iterations and complex fractals, the Mandelbrot set, complex chaos and bifurcations, Fourier and Laplace transforms, fluid dynamics, discrete Fourier and Laplace transforms, Schwarz-Christoffel mapping, mathematical art and tiling of the hyperbolic planes and physics in three and four dimensions (e.g. Minkowski space and twistors). Each chapter uses Mathematica® as a powerful and flexible tool to develop the reader’s geometric intuition and enthusiasm with perfect illustrations and checks of classical calculations (equations, residue, contour integrals, summation of series, mappings and transforms and their inverses). The sophisticated Mathematica® codes - included both in the text and on the CD - enable the user to run computer experiments. The book is far more than a standard course of complex analysis or a guide to Mathematica® tools. Reviewer: Z. Vlasek (Prague) ## Difference Methods for Singular Perturbation Problems Author(s): G. I. Shishkin, L. P. Shishkina Publisher: Chapman & Hall/CRC, CRC Press, Boca Raton Year: 2008 ISBN: 978-1-58488-459-0 Price (tentative): US-$ 119.95
Short description:

This book focuses on the development of robust difference schemes for wide classes of boundary value problems. It justifies the ε-uniform convergence of these schemes and surveys the latest approaches important for further progress in numerical methods.

MSC main category:
65 Numerical analysis
Review:

Part I (Grid approximations of singular perturbation partial differential equations) begins with an introduction containing a short history of the field and its main ideas, the principles and the main problems encountered in the construction of the special schemes in the book. In further chapters of Part 1, the following problems are considered: BVP for elliptic reaction-diffusion equations in domains with smooth and piecewise-smooth boundaries, some generalisations, parabolic reaction-diffusion equations, elliptic convection-diffusion equations and parabolic convection-diffusion equations. Part II (Advanced trends in ε-uniformly convergent difference methods) contains material mainly published in the last four years. This includes problems with boundary layers and additional singularities generated by nonsmooth data, unboundedness of the domain and also by the presence of the perturbation vector parameter. Another aspect considered in this part is that both the solution and its derivatives are found with errors that are independent of the perturbation parameters. The book can be of use for scientists and researchers, both for students and for professionals in the field of developing numerical methods for singularly perturbed problems and also for anybody interested in mathematical modelling or in the fields where the problems with boundary and interior layers arise naturally.

Reviewer:
O. John (Prague)

## Music and mathematics. From Pythagoras to fractals.

Author(s):
John Fauvel, Raymond Flood and Robin Wilson
Publisher:
Oxford University Press
Year:
2006
ISBN:
0-19-851187-6 and 978-0-19-929893-8
Price (tentative):
£18
MSC main category:
00 General
Review:

Leibniz described music as a secret exercise in arithmetic of the soul unaware of its act of counting. The relationship between music and mathematics is much older, having been in existence since at least the time of Pythagoras. Nevertheless, there is a need to remind people from both sides about this relationship. That seems to be the purpose of this book, which aims to demonstrate and analyse “the continued vitality and vigour of the traditions arising from the ancient beliefs that music and mathematics are fundamentally sister sciences”, as stated in the preface. The book is a collection of articles so let us begin by describing their contents, paying special attention to the mathematical aspects.

The book begins with an introductory article, “Music and mathematics: an overview”, by Susan Wollenberg. It contains some notes describing how the relationship between music and mathematics has been perceived and discussed through history and more particularly since the seventeenth century.

Part I: Music and mathematics through history, contains two articles. The first one is “Tuning and temperament: closing the spiral”, by Neil Bibby. It explains one of the most basic facts about the mathematical structure of musical scales. As is well-known, the interval between two notes is given by the ratio of their frequencies. The most basic ratio is 2:1, the octave. Two notes an octave apart are heard as equivalent so to construct a scale other intervals are needed. The next basic interval is the perfect fifth, with frequency ratio 3:2 - a specially pleasing interval. The Pythagorean scale is constructed by adding fifths. One of the fundamental problems in music theory
has always been how many fifths one should add and how those then can be modified conveniently. This resulted in the division of the octave into 12 equal semitones that has pervaded Western music since the 19th century.

The other article is “Musical cosmology: Kepler and his readers”, by Judith V. Field. Seemingly Johannes Kepler believed that geometry and musical harmony could explain the structure of the Universe. This idea, drawn from the ancient tradition of the music of the spheres, was discussed shortly after by Marin Mersenne and Athanasius Kircher.

Part II: The mathematics of musical sound, contains three articles. The first one, “The science of musical sound”, by Charles Taylor, gives a qualitative account of some properties of sound, its perception and its production by musical instruments.

The second article in this part, "Faggot's fretful fiasco", by Ian Stewart, describes a historical accident. In the 18th century, a craftsman Daniel Strähle devised a simple way to determine the position of the frets on a guitar, which in mathematical terms amounts to approximating the 12th root of 2. However, this was dismissed by a mathematician Jacob Faggot due to a regrettable mistake in his calculations. The article discusses Strähle's proposal in terms of fractional approximations and continued fractions.

Finally, "Helmholtz: combinational tones and consonance", by David Fowler, describes two of the many contributions of Hermann Helmholtz to the science of sound. One is of a psychological nature: combinational tones, that is tones that are sometimes heard due to the nonlinearity of the ear. The other one is his explanation of the consonance associated with frequency ratios of small integers in terms that are very close to our present theories.

Part III: Mathematical structure in music, also consists of three articles. The first one, "The geometry of music", by Wilfrid Hodges, studies music from a geometric perspective. The basic dimensions of time and pitch constitute a 2-dimensional space, subject to transformations like translations and rotations. A piece of music may contain motifs, each motif being considered as a subset of the musical space. Motifs are analysed according to their symmetry groups. In the same way, there is a classification of friezes. Many musical examples are given to illustrate all these possibilities.

The second paper in this part is "Ringing the changes: bells and mathematics", by Dermot Roaf and Arthur White. Here, permutation groups and graph theory are applied to solve the old problem of change-ringing, that is to ring a set of bells in all possible orders, without repetition.

"Composing with numbers: sets, rows and magic squares", by Jonathan Cross, describes various usages of numbers by some 20th century composers, from Arnold Schoenberg to Iannis Xenakis. The mathematical models described here are new sources of musical material and, as the author reminds us, the results may be as inspired or as mechanical as in any other musical system.

In Part IV: The composer speaks, two articles can be found. "Microtones and projective planes", by Carlton Gamer and Robin Wilson, deals with microtonal music, based on n equal divisions of the octave. More particularly, they are interested in the case where n = k2-k+1, which is the number of points (and lines) in a finite projective plane. Then there is a connection between the musical inversion and the duality of projective geometry.

Finally, "Composing with fractals", by Robert Sherlaw Johnson, describes a computer program that generates musical patterns based on fractals.

The essays contained in the book concern very different subjects and have different mathematical density and depth. In this sense, the book lacks some coherence and elegance. Nevertheless, this allows the readers to choose their own ways to enjoy some of the connections between music and mathematics. Of course, many other connections are almost absent: the theory of dissonance, spectra of musical instruments, combinatorics of chords and scales, rhythmic patterns, etc. But, in less than 200 pages, the book conveys the idea that both disciplines have been closely related through history and that this relationship is going to remain and even to increase.

Music searches for new ways of expression and mathematics grows unceasingly. Therefore more and more connections will show up between these disciplines. The recent launch of a Journal of Mathematics and Music, and the appearance of books like Dave Benson's ‘Music: a mathematical offering’ is a clear signal in this direction. With respect to this, I would dare say that there lacks an appropriate place in the Mathematics Subject Classification for the many existing and forthcoming literature on mathematics and music. Now that a revision of the classification scheme is in progress, a three-digit section near the end of the list could accommodate the many mathematical faces of music.

Reviewer:
Xavier Gràcia (Barcelona, Spain)

## Elementary Geometry

Author(s):
I. Agricola, T. Friedrich
Publisher:
American Mathematical Society
Year:
2008
ISBN:
978-0-8218-4347-5
Price (tentative):
USD 39
MSC main category:
51 Geometry
Review:

This book is a translation of the German original “Elementargeometrie” published by F. Vieweg and Sohn Verlag in 2005. It is intended as a compendium of the curriculum of elementary geometry for university students. Chapters 1-2 are devoted to an exhaustive study of planar elementary geometry. Many classical theorems are demonstrated including the Ceva theorem, the Menelaus theorem and various properties of triangles, circles and conic sections. Chapter 3 describes the group of Euclidean transformations and its subgroups including discrete ones. Chapter 4 deals with hyperbolic geometry (mainly in the Poincaré model) and in chapter 5 basics of spherical geometry are developed. The main techniques of the book are based on analytical computations in the Euclidean plane, which is introduced as the two dimensional real affine plane with a positive definite quadratic form. Also its identification with the complex line is exploited. Unfortunately, we do not find in the book projective proofs of Euclidean results that are projective in their essence. The book is nicely written, with numerous figures, and the material in the book is organised systematically. It can be widely used by university students and teachers.

Reviewer:
satunnaisuus