To describe the
general behaviour of a predicate, the following vocabulary is employed.
In source code, structured comments contain the corresponding keywords:
det | A deterministic predicate
always succeeds exactly once and does not leave a choicepoint. |
semidet | A semi-deterministic
predicate succeeds at most once. If it succeeds it does not leave a
choicepoint. |
nondet | A non-deterministic
predicate is the most general case and no claims are made on the number
of solutions (which may be zero, i.e., the predicate may fail)
and whether or not the predicate leaves an choicepoint on the last
solution. |
multi | As nondet, but succeeds
at least once. |
undefined | Well founded semantics third
value. See undefined/0. |
