A ⊆ B
A
B A = ∅
A B
A B A B
A
B A B A ∪B
A B A B
A
B
A B A ∩B
A B
A
B A B A \B
A
B
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&
$
%
'
&
$
%
A \BB\AA ∩B
A ∪B
AB
A = {1, 2, 3, 4} B = {2, 3, 5}
A ∪B = {1, 2, 3, 4, 5} A ∩B = {2, 3} A \B = {1, 4} B \A = {5}
X = {1, 3, 5,...} Y = {2, 4, 6,...}
X ∪Y = {1, 2, 3,...} X ∩Y = ∅ X \Y = X Y \X = Y