We present a dynamic data structure for the incremental construction o
f a planar embedding of a planar graph. The data structure supports th
e following operations: (i) testing if a new edge can be added to the
embedding without introducing crossing; and (ii) adding vertices and e
dges. The: time complexity of each operation is O(log n) (amortized fo
r edge insertion), and the memory space and preprocessing time are O(n
), where n is the current number of vertices of the graph. (C) 1996 Ac
ademic Press, Inc.