-Some authors reserve the term "term" for just variables and abstracts. We won't *participate* in that convention; we'll probably just say "term" and "expression" indiscriminately for expressions of any of these three forms.
-
-Examples of expressions:
-
- x
- (y x)
- (x x)
- (_x y)
- (_x x)
- (_x (_y x))
- (x (_x x))
- ((_x (x x)) (_x (x x)))