⊊ (proper subset of)
Tests for a proper subset relation.
Syntax

A ⊊ B

A
andB
are sets

Description
If A
and B
are sets, then A ⊊ B
is true
iff A
is a proper subset of B
, that is, iff every element of A
is also an element of B
but A ≠ B
.
The ⊊
operator is mapped to the ProperSubset
function.
Examples
{ 1, 2, 3 } ⊊ { 1, 2, 3, 4 }
true
See also

Set operators (list)