  We reduce complex stripped patterns to a basic topological network of edges
and vertices to define defects and measure their influence on the pattern. We
present statistics on the spatial and temporal distribution of defects within
the state of spiral defect chaos state in experiments on Rayleigh Benard
convection. These measure the role of boundary influence on the dynamics, and
suggest an exponential distribution for the length of edges in the pattern. We
also indicate a systematic method to study hierarchies of defect interactions
based on the network structure.
