Given nonintersecting simple polygoris P and Q, two vertices p is an e
lement of P and q is an element of Q are said to be visible if <($$)ov
er bar>pq does not properly intersect P or Q. We present a parallel al
gorithm for finding a closest pair among all visible pairs (p,q) p is
an element of P and q is an element of Q. The algorithm runs in time O
(log n) using O(n) processors on a CREW PRAM, where n = \P\+\Q\. This
algorithm can be implemented serially in O(n) time, which gives a new
optimal sequential solution for this problem.