We use associativity and precedence relations among operators. 1. If operator O 1 has higher precedence than operator O 2 , ⇒ O 1 ∙> O 2 and O 2 <∙ O 1 2. If operator O 1 and operator O 2 have equal precedence, they are left-associative ⇒ O 1 ∙> O 2 and O 2 ∙> O 1 they are right-associative ⇒ O 1 <∙ O 2 and O 2 <∙ O 1 3. For all operators O, O <∙ id, id ∙> O, O <∙ (, (<∙ O, O ∙> ), ) ∙> O, O ∙> $, and $ <∙ O 4. Also, let ( ≒ ) $ <∙ ( id ∙> ) ) ∙> $ ( <∙ ( $ <∙ id id ∙> $ ) ∙> ) ( <∙ id