⊆ (subset of or equal to)
Tests for a 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 subset of B
, that is, iff every element of A
is also an element of B
.
The operators ⊂
and ⊆
are both mapped to the subset
function; they are exactly the same.
Examples
{ 1, 2, 3 } ⊆ { 1, 2, 3, 4 }
true
See also

Set operators (list)