>>>>> "Brian" == Brian Rice <water@tscnet.com> writes: Brian> Comments are, of course, highly welcome. Thanks for the clarification. I now understand better what Arrow is all about. Tell me if I'm wrong : a graph is a set of arrow, whose car is a possible input value for a function, and whose cdr is the output value for that input. Right ? -- Laurent Martelli martelli@iie.cnam.fr