Equality
$$A \neq B$$
A is not equal to B
Subset
$$A \not\subseteq B$$
A is not a subset of or equal to B
Superset
$$A \not\supseteq B$$
A is not a superset of or equal to B
Intersection
$$A \cap B =$$
{ }
Union
$$A \cup B =$$
{ concrete operational, formal operational, metaphysics, normative science, phenomenology, pre-operational, sensorimotor }
Symmetric Difference
$$A \ominus B =$$
{ concrete operational, formal operational, metaphysics, normative science, phenomenology, pre-operational, sensorimotor }
Difference
$$A - B =$$
{ metaphysics, normative science, phenomenology }
Difference
$$B - A =$$
{ concrete operational, formal operational, pre-operational, sensorimotor }
Cartesian Product
$$A \times B =$$
{ (metaphysics, concrete operational),
(metaphysics, formal operational),
(metaphysics, pre-operational),
(metaphysics, sensorimotor),
(normative science, concrete operational),
(normative science, formal operational),
(normative science, pre-operational),
(normative science, sensorimotor),
(phenomenology, concrete operational),
(phenomenology, formal operational),
(phenomenology, pre-operational),
(phenomenology, sensorimotor) }
Charles Sanders Peirce