Union
$$A \cup B =$$
{ be, concrete operational, do, exist, feel, formal operational, love, pre-operational, say, see, sensorimotor, think }
Symmetric Difference
$$A \ominus B =$$
{ be, concrete operational, do, exist, feel, formal operational, love, pre-operational, say, see, sensorimotor, think }
Cartesian Product
$$A \times B =$$
{ (be, concrete operational),
(be, formal operational),
(be, pre-operational),
(be, sensorimotor),
(do, concrete operational),
(do, formal operational),
(do, pre-operational),
(do, sensorimotor),
(exist, concrete operational),
(exist, formal operational),
(exist, pre-operational),
(exist, sensorimotor),
(feel, concrete operational),
(feel, formal operational),
(feel, pre-operational),
(feel, sensorimotor),
(love, concrete operational),
(love, formal operational),
(love, pre-operational),
(love, sensorimotor),
(say, concrete operational),
(say, formal operational),
(say, pre-operational),
(say, sensorimotor),
(see, concrete operational),
(see, formal operational),
(see, pre-operational),
(see, sensorimotor),
(think, concrete operational),
(think, formal operational),
(think, pre-operational),
(think, sensorimotor) }
Cognition