
9.3. FURTHER REDUCTION OF EDGE CROSSINGS 295
old and new positions of v. These pertinent edges are visited in order from the old toward
the new position of v. A counter, ctr, holds the number of open edges in the arc (not
including the open edges incident to v). Each time that an endpoint of an edge incident to
v is encountered, the numbe r of crossings is increased by the value in ctr. At the conclusion
of this proces s , the number of crossings caused by v in the old position is known. Th e
number of crossings caused by v in its new position is found by repeating this process from
the new towards the old position of v after moving v to its new