`member`

, we write
something like `member(Item, [a, b, c])`

- first the
predicate name, `member`

, then "(", then the first
argument, `Item`

, then a comma, then the second
argument, `[a, b, c]`

, then ")".
However, with built-in predicates like
`=`

, `<`

and `>`

that are
usually written between their arguments, as in ```
First
< Max
```

, we write, in Prolog as in mathematics, in
*infix* notation. Another infix built-in "predicate" is
`is`

, which is used in
evaluating arithmetic expressions.

It is possible in Prolog to define your own infix (and postfix)
operators, and modify the syntactic handling of prefix operators
- see `op`

.