Memoirs of the American Mathematical Society 2002; 120 pp; softcover Volume: 159 ISBN10: 0821829653 ISBN13: 9780821829653 List Price: US$62 Individual Members: US$37.20 Institutional Members: US$49.60 Order Code: MEMO/159/758
 This memoir develops, discusses and compares a range of commutative and noncommutative invariants defined for projection method tilings and point patterns. The projection method refers to patterns, particularly the quasiperiodic patterns, constructed by the projection of a strip of a high dimensional integer lattice to a smaller dimensional Euclidean space. In the first half of the memoir the acceptance domain is very general  any compact set which is the closure of its interior  while in the second half we concentrate on the socalled canonical patterns. The topological invariants used are various forms of \(K\)theory and cohomology applied to a variety of both \(C^*\)algebras and dynamical systems derived from such a pattern. The invariants considered all aim to capture geometric properties of the original patterns, such as quasiperiodicity or selfsimilarity, but one of the main motivations is also to provide an accessible approach to the the \(K_0\) group of the algebra of observables associated to a quasicrystal with atoms arranged on such a pattern. The main results provide complete descriptions of the (unordered) \(K\)theory and cohomology of codimension 1 projection patterns, formulæ for these invariants for codimension 2 and 3 canonical projection patterns, general methods for higher codimension patterns and a closed formula for the Euler characteristic of arbitrary canonical projection patterns. Computations are made for the AmmannKramer tiling. Also included are qualitative descriptions of these invariants for generic canonical projection patterns. Further results include an obstruction to a tiling arising as a substitution and an obstruction to a substitution pattern arising as a projection. One corollary is that, generically, projection patterns cannot be derived via substitution systems. Readership Graduate students and research mathematicians interested in convex and discrete geometry. Table of Contents  General introduction
 Topological spaces and dynamical systems
 Groupoids, \(C^\ast\)algebras, and their invariants
 Approaches to Calculation I: Cohomology for codimension one
 Approaches to Calculation II: Infinitely generated cohomology
 Approaches to Calculation III: Cohomology for small codimension
 Bibliography
