1.
Note that 1 > nil or 1 < nil is false, because nil is not an
integer. For MUSE networks, we relate position intervals using <,
>, and =.
2.
As a simple demonstration, consider merging nodes 3 and 4 from Figure
5 into a single node such that the
value e and f keep track of the fact that they have
type 3 and 4, respectively. Under these circumstances, CSP arc
consistency will give the same results as MUSE CSP arc consistency;
even though a and c appear in no solutions, they are
not eliminated. Note that this example uses only one role per node.