}:
```
-Single clause predicates can entered without brackets, as in
+Single clause predicates can be entered without brackets, as in
```
l3> p(X) :- q(X).
l3> f(s).
Note that the values of variables belonging to successful queries are
printed out, on one line each. Uninstantiated variables are denoted by
-a number preceded by an underscore (X = _0 is an example in the
+a number preceded by an underscore (`X = _0` is an example in the
above).
## Occurs check