1.3.3.2 Not a Member (∉)

If  is not in , then  is not a member, or does not belong to , denoted by  ∉

A few examples showing the not a member notation:

•  = {heads, tails}, then hearts ∉
•  = {1, 2, 3, 4, 5, 6}, then 7 ∉
• -1 ∉

Equivalently, if we are talking from the perspective of a set, we can say, that  does not contain , denoted by  ∌ . The previous examples can be represented as:

• {heads, tails} ∌ hearts
• {1, 2, 3, 4, 5, 6} ∌ 7
• ∌ -1