Applied Mathematics for Database Professionals

Table B-1.Mathematical Symbols Related to Sets and Functions

Symbol	Description	Examples
:=	Is defined as	P1 := x > y
∈, ∉	Is (not) an element of	x ∈ A, y ∉ A
=, ≠	Is (not) equal to
≥, ≤, <, >	Other comparison operators
⊆	Is a subset of	A ⊆ B
⊇	Is a superset of	A ⊇ B
⊂	Is a proper subset of	A ⊂ B
⊃	Is a proper superset of	A ⊃ B
∪	Union	A ∪ B
∩	Intersect	A ∩ B
−	Difference	A − B
÷	Symmetric difference	A ÷ B
×	Cartesian product	A × B
⊗	Natural join	A ⊗ B
⊘	The empty set
( ; )	Ordered pair	(EMPNO; 102)
⋄	Function composition	f⋄g
⋄⋄	Attribute renaming	T⋄⋄g
dom	Domain of a function	dom(F)
rng	Range ...