# The state of the art for Arrow specs (clarifications and additions)

**Laurent Martelli**
martelli@iie.cnam.fr

*30 Oct 1999 07:09:03 +0200*

>>>>>* "Brian" == Brian Rice <water@tscnet.com> writes:
*
Brian> (3) Treating any graph as a function and applying it to an
Brian> arrow. This relates to the representation of a function as a
Brian> graph, which involves drawing arrows from domain-value to
Brian> range-value. For an actual function, there is only one arrow
Brian> in the graph representation whose input (car) is unique to
Brian> that arrow, ensuring that a function returns at most one
Brian> value.
It looks like the only objects in the system are arrows and set of
arrows. How will you tell a function from a graph, if any graph is a
function, and any function is a graph ? It bothers me because if you
test two objects for equality, and one is supposed to be a graph, and
the ohter one is supposed to be a function, the test may return true
despite the two objects are supposed to be different things.
--
Laurent Martelli
martelli@iie.cnam.fr