THE WRITHE OF ORIENTED POLYGONAL GRAPHS
Abstract
Given an edge-oriented polygonal graph in ℝ3, we describe a method for computing the writhe as the average of weighted directional writhe numbers of the graph in a few directions. These directions are determined by the graph and the weights are determined by areas of path-connected open regions on the unit sphere. Within each open region, the directional writhe is constant. We obtain a closed formula which extends the formula for the writhe of a polygon in ℝ3, including the important special case of writhe of embedded open arcs.