.\" bintree.pic -- a binary tree example 
.\" $Id$
.\" Carlos Duarte, 971122/981025
.\"
.PS
scale=2.54*1.2
a=3
b=1.4
circle
circle at 1st circle + (-a,-a)
circle at 1st circle + (a,-a)
circle fill 0.3 "x" at 2nd circle + (-b,-a)
circle at 2nd circle + (b,-a)
circle at 3nd circle + (-b,-a)
circle at 3nd circle + (b,-a)
arrow from 1st circle to 2nd circle chop 
arrow from 1st circle to 3rd circle chop 
arrow from 2nd circle to 4th circle chop 
arrow from 2nd circle to 5th circle chop 
arrow from 3rd circle to 6th circle chop 
arrow from 3rd circle to 7th circle chop 
.PE