foo refers to process-inst-ref check_invs<>
Fanins of node `x':
(from foo):
[after 10]	~a -> x+
[after 10]	a -> x-
Fanins of node `y':
(from foo):
[after 10]	~b -> y+
[after 10]	b -> y-
allrings-chk: 
checked exclhi rings:
{ x, y }
checked excllo rings:
checked rings of a: 
checked exclhi rings of which `a' is a member:
checked excllo rings of which `a' is a member:
checked rings of b: 
checked exclhi rings of which `b' is a member:
checked excllo rings of which `b' is a member:
checked rings of x: 
checked exclhi rings of which `x' is a member:
{ x, y }
checked excllo rings of which `x' is a member:
checked rings of y: 
checked exclhi rings of which `y' is a member:
{ x, y }
checked excllo rings of which `y' is a member:
