Sophie: gprolog-1.2.16-3mdk ppc

gprolog-1.2.16-3mdk.ppc.rpm

diff(fdv X,fdv Y,int I)

{
 start X in ~{val(Y),val(Y)+I,val(Y)-I}
 start Y in ~{val(X),val(X)+I,val(X)-I}
}