Electronic Colloquium on Computational Complexity, Report No. 25 (2003) Constant width planar computation characterizes ACC 0

We obtain a characterization of ACC 0 in terms of a natural class of constant width circuits, namely in terms of constant width polynomial size planar circuits. This is shown via a characterization of the class of acyclic digraphs which can be embedded on a cylinder surface in such a way that all arcs flow along the same direction of the axis of the cylinder.