The following identifies the main reasons why the CLP( 
) implementation
does not perfectly conform to the idealized CLP scheme.
) makes use of double precision floating
point arithmetic, some problems may be caused by artifacts such as roundoff.
The most common problem is that a constraint used as a test (in that all
variables are ground) unexpectedly fails because of round-off. This is dealt
with by adjusting the amount of slack that the system allows in numerical
comparisons, using the -z command line option.