Arithmetic expression

arithmetic-expression :=
  [(] [unary-arithmeticoperator] numeric-operand 
  [ binary-arithmetic-operator arithmetic-expression ] [)]

numeric-operand :=
    variable
  | literal
  | arithmetic-expression

unary-arithmetic-operator :=
    +
  | -

binary-arithmetic-operator :
    +
  | -
  | *
  | /