Topological invariants for projection method patterns
  We analyze and compare different dynamical systems and groupoids which can be obtained from projection point patterns. We define the cohomology of a point pattern as the cocycle cohomology of the pattern groupoid. We describe this cohomology qualitatively and calculate it for canonical projection method tilings with codimension smaller or equal than 3. 
Alan Forrest, John Hunton, Johannes Kellendonk