WARNING: weak-interference `c'
>> cause: `b' (val: 1)
	0	b : 1
	0	a : 1
	10	c : 0	[by a:=1]
	20	d : 1	[by c:=0]
Nodes with interference:
Nodes with weak-interference:
	20	b : 0
	20	a : 0
expect c+ in queue 
queue:	30	c : 1	[from a:=0]
Nodes with interference:
Nodes with weak-interference:
WARNING: interference `c'
>> cause: `b' (val: 1)
	24	b : 1
expect c -> X in queue 
queue:	30	c : X	[from b:=1]
WARNING: weak-interference `d'
>> cause: `c' (val: X)
	30	c : X	[by b:=1]
	40	d : X	[by c:=X]
Nodes with interference:
c
Nodes with weak-interference:
d
