Problem with CLP

[Lars Riis Olsen]

Hi

I am new to GNU Prolog and I have run into a problem concerning its CLP 
extension. I don't know whether it is a bug or whether it is just me who 
have misunderstood something. The problem is that GNU Prolog says that 
the following query is satisfiable:

fd_domain(X,0,15), fd_domain(Y,0,15), (((X #< Y) #/\ ((Y-X) #> 8))   
#\/   ((X #> Y) #/\ ((X - Y) #< 8))) #/\   (((X #< Y) #/\ ((Y-X) #< 
8))   #\/   ((X #> Y) #/\ ((X - Y) #> 8))).

more specifically it returns the following answer:

X = _#3(0..15)
Y = _#25(0..15)

From the query it should be clear that it is indeed not satisfiable. 
Furthermore to recheck this I tried to further constraint the value of 
the variable X to be eg. 0. In this case it comes up with the correct 
answer (no). The same happens if X is instead constrained to 1,2,3... 
and so forth.

I am using GNU Prolog version 1.2.17

Any ideas to what might be wrong.

Regards
Lars