Union
$$A \cup B =$$
{ action, brainstem, cerebellum, cerebrum, contemplation, maintenance, precontemplation, preparation, termination }
Symmetric Difference
$$A \ominus B =$$
{ action, brainstem, cerebellum, cerebrum, contemplation, maintenance, precontemplation, preparation, termination }
Difference
$$B - A =$$
{ action, contemplation, maintenance, precontemplation, preparation, termination }
Cartesian Product
$$A \times B =$$
{ (brainstem, action),
(brainstem, contemplation),
(brainstem, maintenance),
(brainstem, precontemplation),
(brainstem, preparation),
(brainstem, termination),
(cerebellum, action),
(cerebellum, contemplation),
(cerebellum, maintenance),
(cerebellum, precontemplation),
(cerebellum, preparation),
(cerebellum, termination),
(cerebrum, action),
(cerebrum, contemplation),
(cerebrum, maintenance),
(cerebrum, precontemplation),
(cerebrum, preparation),
(cerebrum, termination) }