∌ (does not contain as member)
Tests for set nonmembership.
Syntax

A ∌ a

A
is a set 
a
is any object

Description
If a
is any object and A
a set, then A ∌ a
returns true
iff a
is not an element of A
.
If the cardinality of A
is reasonably small, floatingpoint values are compared individually with epsilon. However, if the cardinality is very large, a different algorithm may be used to improve performance, which may not be epsilonbased.
The ∌
operator is implemented by the NotContainsAsElement
function.
Examples
A ≔ {−1, 0, 1}
{1, −1, 0}
A ∌ sin(π)
false
See also

Set operators (list)