Computing the Continuous Discretely

This much-anticipated textbook illuminates the field of discrete mathematics with examples, theory, and applications of the discrete volume of a polytope. It weaves a unifying thread through basic yet deep ideas in discrete geometry, combinatorics, and number theory.

The world is continuous, but the mind is discrete. David Mumford We seek to bridge some critical gaps between various ?elds of mathematics by studying the interplay between the continuous volume and the discrete v- ume of polytopes. Examples of polytopes in three dimensions include crystals, boxes, tetrahedra, and any convex object whose faces are all ?at. It is amusing to see how many problems in combinatorics, number theory, and many other mathematical areas can be recast in the language of polytopes that exist in some Euclidean space. Conversely, the versatile structure of polytopes gives us number-theoretic and combinatorial information that ?ows naturally from their geometry. Fig. 0. 1. Continuous and discrete volume. The discrete volume of a body P can be described intuitively as the number of grid points that lie inside P, given a ?xed grid in Euclidean space. The continuous volume of P has the usual intuitive meaning of volume that we attach to everyday objects we see in the real world. VIII Preface Indeed, the di?erence between the two realizations of volume can be thought of in physical terms as follows. On the one hand, the quant- level grid imposed by the molecular structure of reality gives us a discrete notion of space and hence discrete volume. On the other hand, the N- tonian notion of continuous space gives us the continuous volume.

The authors write with flair and have chosen a unique set of topics Places a strong emphasis on computational techniques Contains more than 200 exercises and has been heavily class-tested Includes hints to selected exercises Includes supplementary material: sn.pub/extras

Inhalt
The Essentials of Discrete Volume Computations.- The Coin-Exchange Problem of Frobenius.- A Gallery of Discrete Volumes.- Counting Lattice Points in Polytopes:The Ehrhart Theory.- Reciprocity.- Face Numbers and the DehnSommerville Relations in Ehrhartian Terms.- Magic Squares.- Beyond the Basics.- Finite Fourier Analysis.- Dedekind Sums, the Building Blocks of Lattice-point Enumeration.- The Decomposition of a Polytope into Its Cones.- EulerMaclaurin Summation in ?d.- Solid Angles.- A Discrete Version of Green's Theorem Using Elliptic Functions.