Before revision: We revisit the randomized incremental construction of the Trapezoidal Search DAG (TSD) for a set of{\cal   n non-crossing segments, e.g. edges from planar subdivisions.
After revision: We revisit the randomized incremental construction of the Trapezoidal Search DAG (TSD) for a set of{\cal O n non-crossing segments, e.g. edges from planar subdivisions.